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Ammonia emission patterns of typical planting systems in the middle and lower reaches of the Yangtze River and key technologies for ammonia emission reduction
XIA Yongqiu, WANG Shenqiang, SUN Pengfei, CHEN Xiaoqin, SHEN Jianlin, WANG Hua, XIAO Zhihua, LI Xiaoming, YANG Guang, YAN Xiaoyuan
 doi: 10.12357/cjea.20210247
Abstract(20) HTML(6) PDF(9)
Rice, vegetables, and fruit fields in the middle and lower reaches of the Yangtze River are the main sites of ammonia volatilization in the planting system of China. Therefore, there is an urgent need to understand the characteristics and key control technologies of ammonia emissions in the middle and lower reaches of the Yangtze River. This paper systematically reviewed the major progresses of the National Key Research and Development Project of the National 13th Five-Year Plan: “Research and Development of Key Technologies for Efficient Ammonia Control and Emission Reduction in Planting System in the Middle and Lower Reaches of the Yangtze River,” and foreseen the research focus during the 14th Five-Year period. The main research results included the followings: 1) The ammonia emission coefficient and characteristics of typical rice, and vegetables and fruit trees fields were identified, indicating that the paddy field had the largest ammonia emission coefficient and variation, averaging 14.2%, followed by open-air vegetables (averaging 11.2%), and fruit fields (averaging 4.76%). 2) After verifying the whole process of ammonia emission reduction, “reduction, retrain, control, and immobilization”, we put forward technologies such as optimized nitrogen reduction technology in paddy fields, deep fertilizer applications for ammonia emission control technology in paddy fields, ammonia emission immobilization by periphyton technology in paddy fields, deep application of large-size granular fertilizer for fruit trees, and slow-release fertilizer for open-air vegetables. With these technologies, we achieved the goals of reducing ammonia volatilization. During the 14th Five-Year Plan period, the long-term in-situ monitoring and simulation of ammonia volatilization should be strengthened, ammonia emission reduction technologies should be evaluated environmentally and economically, and simple and low-cost ammonia volatilization emission reduction technology should be developed.
Topsoil organic matter and its effect on the soil nutrients contents of Cunninghamia lanceolata plantations
YUWEN Ruinan, PAN Chang, GUO Jiahuan, FENG Huili, CHEN Jie, YU Yuanchun
 doi: 10.13930/j.cnki.cjea.210211
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Soil organic matter plays an important role in forest ecosystems and is an important index for estimating soil carbon storage and soil fertility and quality. In this study, the distribution of soil organic matter and its influence on soil nutrients were analyzed on a provincial scale and the impact of environmental factors on changes in the soil organic matter content of Chinese fir plantations (CFPs) was assessed to provide a theoretical basis for the sustainable management of CFPs. Data from 1092 forest farms in six provinces of China (Guangdong, Guangxi, Hunan, Jiangxi, Zhejiang, and Fujian) were used to characterize the distribution of soil organic matter and its effect on the soil nutrients in the topsoil (0–20 cm) in CFPs. The results showed that the average soil organic matter content of the CFPs was 31.02±13.44 g·kg−1, the nutrient grade was at a medium level, and the coefficient of variation was 43.33%, which represented a moderate variation level. The available phosphorus (AP) content was 5.41±8.01 mg·kg−1, the nutrient grade was rich, and the coefficient of variation was as high as 148.06%. The total phosphorus (TP) content was 0.49±0.38 g·kg−1, which was extremely poor, and the coefficient of variation was 77.55%, being moderately variable. The soil organic matter content of different soil types varied greatly. The content in mountain yellow soil was the highest (46.63±16.88 g·kg−1), and that in dark red soil was the lowest (15.81±4.38 g·kg−1). Stand density, elevation, slope, and soil pH were the main factors that affected the soil organic matter content in the topsoil of CFPs, with relative contributions of −0.35, 0.28, 0.11, and 0.11, respectively. The contributions of soil organic matter to total nitrogen (TN), available nitrogen (AN), total potassium (TK), and available potassium (AK) were positive, with relative contributions of 0.17, 0.47, 0.16, and 0.21, respectively. However, soil organic matter contributes less to soil TP, with a relative contribution of −0.09. In general, the nutrient grade of soil organic matter in the surface layer of CFPs was medium. The main grading performance was mainly characterized by moderate to inferior levels, and few rich levels and no extremely poor levels were observed. Altitude, slope, and soil pH had positive effects on soil organic matter, whereas stand density had a negative effect. Soil organic matter had a positive effect on soil TN, AN, TK, and AK and a weak negative effect on TP. The contribution of soil organic matter to TP was low; therefore, the lack of phosphorus in the soil may be the main factor limiting Chinese fir growth.
Effects of different biogas slurries on soil microbial carbon metabolism
LI Yufei, XU Junxiang, LIU Bensheng, SUN Qinping, LI Jijin, LIU Jianbin, LANG Qianqian, SUN Renhua, JIN Hongyan
 doi: 10.12357/cjea.20210274
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Biogas slurry is a high-quality organic fertilizer, but different types of biogas slurries have different physical and chemical properties. To explore the effect of biogas slurries derived from different livestock and poultry wastes on the soil microbial community structure, a culture experiment was conducted in the laboratory with the following treatments: soil amended with biogas slurry from chicken manure (FS), pig manure (PS), and cow manure (CS), and an unamended control (CK). The experiment was conducted with equal nitrogen input for each treatment. Samples were collected after incubation of soil for 60 days. Changes in the carbon metabolism of microbial communities subjected to different treatments were examined using the Biolog microplate culture method. Compared to the control, the biogas slurry treatments exerted no significant effect on soil organic matter content, but improved soil pH, electrical conductivity, and contents of inorganic nitrogen, total nitrogen, available phosphorus, and available potassium to varying degrees. Soil microbial biomass carbon was highest in CS, whereas that in PS was significantly lower than that in CK (P<0.05). The highest carbon source utilization intensity was found in FS, while that in CS was similar to that in CK, and lower in PS. Carbohydrate utilization by soil microbes was highest in FS, where it showed a significant increase with respect to that of PS (P<0.05). The utilization of amino acids was inhibited by all biogas slurry treatments; however, such inhibition was significant only in PS when compared with CK (P<0.05). Carboxylic acid utilization was significantly higher in FS than that in the other treatments (P<0.05). The various treatments exerted three distinct effects on amine utilization: on the one hand, FS promoted amine utilization, which showed values significantly higher than those in CK and PS (P<0.05); on the other hand, PS treatment did not significantly affect amine utilization when compared to that of CK; and finally, there was no significant difference in amine utilization between microbial communities subjected to CS and the other treatments. When compared with the other treatments, FS resulted in soil microbial communities with significantly higher values of both Shannon and Simpson indices (P<0.05). The highest value of the McIntosh index was observed in the FS-treated community, with a significant increase with respect to that of PS. Amino acid utilization was the parameter showing the strongest correlations (P<0.05 or P<0.01) with various soil chemical properties. Particularly, significant negative correlations were observed with nitrate nitrogen content, total nitrogen content, available potassium content, and electrical conductivity. In contrast, there were no significant correlations between the diversity indices and soil chemical properties. Soil microbial biomass carbon was negatively correlated with nitrate and available potassium contents (P<0.05). Conversely, soil microbial biomass nitrogen was negatively correlated with the pH and electrical conductivity (P<0.05). Principal component analysis of microbial carbon metabolism showed that the microbial community of PS was differed from that of CK, while CS and FS had relatively small effects on microbial community metabolism. In summary, biogas slurry derived from different livestock and poultry wastes exerted different effects on soil microbial carbon metabolism. Nevertheless, future experiments are required to verify the long-term effects of different biogas slurries in the field.
Growth promotion and mitigation of salt stress in wheat seedlings by a Kushneria bacterium
YUAN Lin, WANG Xinzhen, SUN Hongyong, LIU Xiaojing, LIU Binbin
 doi: 10.12357/cjea.20210144
Abstract(11) HTML(0) PDF(10)
Globally, soil salinization is a major land degradation process, taking more than 1 million hectares of farmland out of production per year, threatening food security. In salt-affected soils, crop growth, development, and yield dramatically decrease due to salt toxicity in plants, reduced soil fertility and water availability to plants, and altered hydraulic properties of the soil. The rhizospheric microbiome is closely related to crop stress tolerance. Plants recruit specific groups of microbes in the rhizosphere, which provide nutrients and plant hormones that promote plant growth and stress tolerance. Kushneria indalinina JP-JH is a salt-tolerant and auxin-secreting bacteria strain isolated from the rhizosphere of Suaeda salsa. In this study, the effects of K. indalinina JP-JH on the growth and salt tolerance of wheat seedlings were investigated. The experiment was conducted using the wheat variety ‘Xiaoyan 60’ in a hydroponic system with Hoagland nutrient solution. The seedlings were inoculated with K. indalinina JP-JH under no salt (0 mmol∙L−1), low salt (200 mmol∙L−1), and high salt (400 mmol∙L−1) conditions. Seeds without bacterial inoculation were prepared under the same conditions and used as control treatments. Plant growth parameters and organic acids contents in the root exudates were analyzed after 40 days of incubation. The results showed that the fresh weight of wheat seedlings in the treatments with K. indalinina JP-JH inoculation was significantly higher than that of the uninoculated group at all three salt concentrations. K. indalinina JP-JH inoculation significantly increased the plant dry weight of the whole plant under both salt-free and low salt-stressed conditions but had no significant effect on dry weight under high salt-stressed conditions. Meanwhile, K. indalinina JP-JH inoculation significantly increased plant height under high salt-stressed conditions but had no significant effect under salt-free and low salt-stressed conditions. Dry weight and plant height were negatively related to the salt concentration in the inoculated and uninoculated treatments. The concentrations of six organic acids (oxalic acid, tartaric acid, malic acid, citric acid, fumaric acid, and succinic acid) secreted from roots were determined for treatments with different salt concentrations, with or without bacterial inoculation. K. indalinina JP-JH inoculation significantly increased the contents of oxalic acid and tartaric acid in the root exudates under salt-stressed conditions (both low and high salt concentrations) but had no significant effect on organic acids secretion under salt-free conditions. This suggests that oxalic acid and tartaric acid may play important roles in regulating plant-microbe interactions and improving the salt tolerance of wheat variety ‘Xiaoyan 60’. Taken together, our results indicate that K. indalinina JP-JH promotes plant growth and development and improves the salt tolerance of wheat at seedling stage, which may be related to alterations in the root exudation potential and plant-microbe interactions. This study produced new experimental data on the mechanisms of microorganisms that promote plant growth and salt tolerance and provided biological resources for developing biofertilizers to enhance wheat growth under salt stress conditions.
Effect of seedling size on the medicinal properties of Codonopsis pilosula under organic cultivation
LIU Lanlan, GUO Fengxia, CHEN Yuan, CHEN Yongzhong, WANG Hongyan, ZHANG Biquan, GUO Aihui
 doi: 10.13930/j.cnki.cjea.210188
Abstract(19) HTML(9) PDF(3)
Ecological organic cultivation is an increasing trend in the industrialized development of traditional Chinese medicine. The medicinal properties of Codonopsis pilosula vary with seedling size. To explore the effects of seedling size on medicinal formation in organic cultivated C. pilosula, seedlings were categorized as big (BS), middle (MS), small (SS), and slender (SLS) seedlings and transplanted under full organic conditions to comparatively evaluate the yield and medicinal characteristics of the medicinal roots. The results showed that the seedling sizes had an allometric growth pattern. After transplantation, bigger seedlings showed earlier regreening, greater growth at the early stages and weaker growth at the later stages with significant increases in lateral roots number, and higher water content of roots, and higher disease incidence. The smaller seedlings showed later regreening, faster growth at the mid and later stages with increased diameter, less root water content and lower disease incidence. These differences led to non-significant differences in the single root weight and total medicinal yield. The average fresh medicinal yields of MS (8225.1 kg·hm–2) and SS (8125.0 kg·hm–2) were the highest and second highest, respectively, increasing by 23.4% and 21.9% compared with the BS group and by 45.2% and 43.4% compared with the SLS group. The average dry medicinal yield of SS (2938.1 kg·hm–2) and MS (2681.1 kg·hm–2) was the highest and second highest, increasing by 37.8% and 25.7% compared with the BS group and by 53.6% and 40.1% compared with the SLS group, respectively. Among the four seedling sizes, the root disease incidence did not significantly differ, ranked as BS (6.4%) > MS (5.6%) > SS (3.9%)> SLS (3.6%). However, the disease severity showed significant differences, and the disease indices for MS and BS were 4.66% and 2.93%, respectively, both of which were significantly higher than those for SLS (1.32%) and SS (0.97%). The comprehensive evaluation indices were SS (0.734) > SLS (0.636) > MS (0.409) > BS (0.282). In summary, yield did not increase with seedling size largening. Plant seedlings have strong plasticity and manifest various strategies for establishment during the medicinal formation period. These results challenge the traditional selection and retention practices for plant seedlings, suggesting that the big seedlings should not be blindly chosen and that the slender seedlings should not be eliminated during production. Slender plants should be cultivated by increasing the transplantation density and controlling pests and birds to improve the regreening rate, whereas larger seedlings should be cultivated by decreasing the density. Together, these practices could improve the effectiveness of C. pilosula organic cultivation.
Effect of micro-nano bubbles on the yield of different rice types
QIAN Yinfei, CHEN Jin, SHAO Caihong, GUAN Xianjiao, QIU Caifei, CHEN Xianmao, LIANG Xihuan, XIE Jiang, DENG Guoqiang, PENG Chunrui
 doi: 10.13930/j.cnki.cjea.210194
Abstract(37) HTML(20) PDF(5)
Increasing the rhizosphere oxygen in the rice paddy can influence the paddy field environment and improve the physiology, metabolism, and grain yield of rice. The traditional methods of mechanically or chemically aerating subsurface irrigation could produce large air bubbles, which can escape from the soil along the pores adjacent to the roots. Aerating irrigation efficiency improvement is an issue not yet to be resolved. One way is to use water rich in micro-nano bubbles (MNB). MNB are small air bubbles that cannot escape from the soil easily, thereby, supplying more oxygen. Different rice types vary in their ability to absorb and utilize oxygen. A pot experiment was carried out in which the experimental group was treated with MNB water and the control group with running water as check (CK) during 2019−2020 to determine the effect of MNB and CK on the growth and yield of two paddy rice varieties (inbred rice ‘Ganwanxian 37’ and super rice ‘Wufengyou T025’). The results showed that 1) MNB increased the dissolved oxygen concentration of soil solution, increased the number and volume of rice roots, enhanced α-NA oxidation, improved the total and active absorption area of root, promoted the SPAD and net photosynthetic rate (Pn) value of leaves, increased the biomass accumulation, raised the harvest index, improved the rice panicle characteristics such as length and number of grains per panicle, enhanced the number of primary and secondary branches and also the main spike-stalk, seed-setting rate on the primary and secondary branches and on spike-stalk, and enhanced the grain yield. 2) Compared to CK, MNB enhanced the yield of inbred rice by 8.46%–17.9% and super rice by 11.32%–22.09%, with the super rice showing higher grain yield than the inbred rice. 3) In case of inbred rice, MNB mainly increased the panicles (6.67%–16.67%), whereas in super rice it increased the spikelets per panicle (3.23%–7.2%) and the seed-setting rate (1.14%–6.57%). 4) The MNB enhanced the panicles number of inbred rice by promoting the tiller occurrence in the early growing period. The MNB enhanced the number of spikelets per panicle and the seed-setting rate in the super rice by increasing the rate of photosynthesis of leaves (improved the SPAD and Pn value). It also slowed down the leaf senescence, improved the bearing rate of tillers, biomass accumulation, increased the number and seed-setting rate in the secondary branches and the main spike-stalk, and it improved the harvest index. It was, thus, evident that MNB could improve the yield of both types of rice. In inbred rice, supplying MNB before the tillering stage increases the yield by increasing panicles number. In super rice, MNB supply after the earing stage increases the yield by producing more spikelets per panicle and through higher seed-setting rate.
Effect of green manure on soil water and crop yield in the Loess Plateau of China: A Meta-analysis
ZHANG Shaohong, WANG Jun, RAJAN Ghimire, XING Wenchao, HU Yingming, ZHANG Nannan
 doi: 10.13930/j.cnki.cjea.210243
Abstract(60) HTML(5) PDF(21)
Planting green manure is a long-established planting pattern in the dryland cropping areas across the Loess Plateau of China. However, due to limited precipitation, planting green manure may reduce soil water content and affect the succeeding crop yield. By combining data from 46 peer-reviewed publications, a Meta-analysis was carried out to assess the effect of green manure on precipitation storage efficiency (PSE) during the fallow period, soil water storage at succeeding crop planting (SWSP), succeeding crop yields, evapotranspiration (ET), and water use efficiency (WUE) in the Loess Plateau of China. Compared to fallow areas without green manure, area with green manure decreased PSE, SWSP and ET by 28.28% (P<0.05), 4.93% (P<0.05) and 2.51% (P<0.05), respectively, however, it increased succeeding crop yield and WUE by 2.37% and 8.97% (P<0.05), respectively. Green manure effect on soil water, crop yield, and soil water use varied with the interval between green manure termination and planting of succeeding crop, green manure biomass, and climatic conditions. Strong polynomial relationship was found between the response ratios (RRs) of PSE, SWSP and the interval between legume green manure termination and succeeding crop planting. Both PSE and SWSP maximized at an interval of 13 d. The RRs of crop yield and WUE were also correlated with legume green manure biomass in a polynomial way. Succeeding crop yield and WUE maximized when the legume green manure biomass was 2200 and 3100 kg∙hm−2, respectively. Overall, introducing green manure during fallow period reduced soil water but enhanced succeeding crop production and water use in the Loess Plateau. Leaving a 12–14 d interval between legume green manure termination at a biomass of 2200–3100 kg∙hm−2, succeeding crop planting can be a reliable practice to mitigate soil water consumption in such dryland areas.
Effect of nitrogen fertilizer amount on N2O emission from wheat-maize rotation system in lime concretion black soil
LYU Jinling, GAO Yanbu, LI Taikui, KONG Haijiang, ZHANG Jinping, KOU Changlin
 doi: 10.12357/cjea.20210444
Abstract(11) HTML(3) PDF(3)
Lime concretion black soil is an important medium and low-yield soil in the Huanghuaihai Plain. It is prone to cracks because containing a high clay and sand ginger layer, making it unique in nitrogen transport. This study used the wheat and corn rotation system in lime concretion black soil as the research object, researching the N2O emission characteristics and key driving factors by static box-gas chromatography methods. The experiment included four treatments: no fertilization (CK), traditional fertilization (TR), optimized fertilization (OPT), and re-optimized fertilization (ZOPT). Results showed that the average emission flux of N2O in the wheat season ranged from 14.2 to 21.6 μg∙m−2∙h−1, and the cumulative emission amount ranged from 0.82 to 1.24 kg(N)∙hm−2; the average emission flux of N2O in the corn season ranged from 14.4 to 24.5 μg∙m−2∙h−1, the cumulative emission amount ranged from 0.42 to 0.71 kg(N)∙hm−2; the N2O emission in the wheat season was higher than that in the corn season, and the N2O emission in the top dressing period of the two seasons was higher than that in the basal fertilizer period, demonstrating that the wheat season and top dressing period were high N2O emission periods for lime concretion black soil. The correlation analysis results showed that N2O emission of CK showed a significant multiple linear correlation with soil temperature, water content, and NO3-N content (P<0.05); whereas that of TR, OPT, and ZOPT only showed a significant multiple linear correlation with soil nitrate (P<0.01). There was no significant correlation between soil temperature and soil water content (except in individual cases), indicating that under fertilization conditions, the level of soil nitrate content was the most critical factor affecting N2O emissions from the farmland of lime concretion black soil. In addition, the cumulative N2O emissions of different nitrogen application rates were significantly different (P<0.05), and the N2O emissions of the TR treatment were the highest, which were 1.24 kg(N)∙hm−2 and 0.71 kg(N)∙hm−2, respectively, in the wheat and corn seasons, significantly higher than those of OPT treatment [0.99 kg(N)∙hm−2 and 0.51 kg(N)∙hm−2] and ZOPT treatment [0.82 kg(N)∙hm−2 and 0.42 kg(N)∙hm−2]. The cumulative emissions of N2O in both the wheat and corn seasons showed an exponentially increasing trend with the increase in nitrogen application, with the correlation coefficients reaching 0.997 and 0.977 (P<0.05), respectively, indicating that the traditional lime concretion black soil nitrogen application had the problem of excessive emissions of N2O. Overall, compared with other soils, although lime concretion black soil is not a high-emission soil of N2O, the N2O emission caused by higher nitrogen application cannot be ignored.
Prediction of suitable climatic areas for Fortunella species in China
ZHANG Yi, XUE Shuai, HUANG Hongmei, LI Dazhi, TANG Shuai, KONG Weizheng, YI Zili
 doi: 10.12357/cjea.20210416
Abstract(4) HTML(12) PDF(1)
Fortunella is one group of the citrus fruit trees in southern China, a kind of edible hesperidium with rich flavonoids, carotenoids, limonoids, coumarins, and the fruit of these evergreen trees also have ornamental value. In recent years, areas of growth of commercial species of Fortunella have been decreasing due to a low net interest of planting single species. Meanwhile, natural resources have also withered due to the Huanglong disease caused by gram-negative bacteria. National collection of germplasm resources of Fortunella has been completed in parts of China, including Hunan, Fujian, Guangxi, etc.; however, this work did not take the effects of climatic factors on their distribution into consideration, which could provide a scientific basis for protection and collection of natural resources of Fortunella species. In this study, we predicted suitable climatic areas for six species (F. hindsii Swingle, F. margarita Swingle, F. japonica Swingle, F. polyandra Tanaka, F. crassifolia Swingle, and F. obovata Tanaka) of Fortunella using the MaxEnt (the maximum entropy, MaxEnt 3.3.3) model and the ArcGIS (the geographic information, ArcGIS 10.3) system to analyze actual geographical distribution data and 18 climate factors affecting their distribution. The dominant climate factors were screened through Jackknife test. Results showed that the suitable climatic region for the six species analyzed were distributed mainly in the southern areas of Dabie—Daba Mountain. The suitable region for the six species covered 354 000 km2 (F. hindsii Swingle), 276 100 km2 (F. margarita Swingle), 495 800 km2 (F. japonica Swingle), 613 600 km2 (F. polyandra Tanaka), 474 400 km2 (F. crassifolia Swingle), and 663 403 km2 (F. obovata Tanaka). The optimum climate region for F. polyandra Tanaka mainly extended to Chongqing, Guangxi, Guangdong, Hainan, and south of Yunnan, while that for the other five species was predominantly distributed in Hunan, Jiangxi, Guangxi, Fujian, Zhejiang, and Guangdong; some favorable region for F. obovata Tanaka even extended to Chongqing. The main climatic factors affecting the growth of Fortunella include minimum temperature, precipitation, and isothermality. The major climatic factors affecting F. hindsii Swingle distribution included isothermality and precipitation in April and June, while for F. margarita Swingle such climatic factors comprised precipitation in April and June, minimum temperature in February and July, and isothermality and precipitation in the driest month. Similarly, geographical distribution of F. japonica Swingle was influenced by precipitation in April and June, minimum temperature in July, isothermality and precipitation in the driest month, and precipitation in the warmest quarter. Likewise, the major climatic factors affecting natural distribution of F. polyandra Tanaka comprised precipitation in July and in December, minimum temperature in February and June, isothermality, and mean precipitation in the warmest quarter. Similar analytical results demonstrated that the dominant climatic factors affecting the distribution of both F. crassifolia Swingle and F. obovata Tanaka were in terms of precipitation in June, and isothermality and mean precipitation of the warmest quarter. The area under the curve (AUC) value of the MaxEnt model for all six species exceeded 0.9 and their actual distribution areas were also integrated, which indicated that the predicted distribution range of this study was highly accurate. Consequently, these results are expected to provide scientific guidance for regional investigation and protection of wild species of Fortunella and promotion of its varieties.
Effect of phosphorus fertilizer rate on phosphorus fractions contents in calcareous soil and phosphorus accumulation amount in crop
XU Xiaofeng, MI Qian, LIU Di, FU Senlin, WANG Xugang, GUO Dayong, ZHOU Wenli
 doi: 10.13930/j.cnki.cjea.210186
Abstract(38) HTML(15) PDF(10)
Excessive application of phosphate fertilizer wastes phosphorus resources and induces eutrophication in lakes and rivers. To study the effect of reduction of phosphorus fertilizer on phosphorus fractions in calcareous soil and its relationship with crop phosphorus accumulation, three treatments were set up, i.e., phosphorus application rates of 150 kg∙hm−2 (P150), 37.5 kg·hm−2 (P37), and 0 kg∙hm−2 (P0). After two consecutive years of “winter wheat-summer maize” crops rotation, the changes in the contents of soil phosphorus fractions were studied using Hedley soil phosphorus fractionation method, and the storage contribution rate and output contribution rate of each fraction were also estimated. The relationship between soil phosphorus fractions contents, phosphorus fertilizer application rate, and crop phosphorus uptake amount were explored by using regression analysis, path analysis, and structural equation model. The results showed that compared with P37, P150 led to a significant increase in soil total phosphorus content. The contents of inorganic phosphorus extracted with anion exchangeresin (resin_Pi), with NaHCO3 (NaHCO3_Pi), with NH4OAc (NH4OAc_Pi) and with NaOH-Na2S2O6 (Fe_Pi), and organic phosphorus extracted with NaHCO3 (NaHCO3_Po) in P150 were significantly higher than those in P37, while the other fractions showed no significant change. P0 did not cause a significant decrease in the contents of soil phosphorus fractions. The storage contribution rates of soil inorganic phosphorus fractions and organic phosphorus fractions were 72.6% and 23.8%, respectively. Among them, the storage contribution rates of inorganic phosphorus extracted with HCl (HCl_Pi), Fe_Pi, NH4OAc_Pi, resin_Pi, and organic phosphorus extracted with HCl (HCl_Po) were 24.45%, 18.1%, 13.62%, 11.15%, and 9.30%, respectively. The output contribution rate of soil inorganic phosphorus fractions was 41.0%, and that of organic phosphorus fractions was 56.4%. Among them, the output contribution rates of HCl_Po, Fe_Pi, and NH4OAc_Pi were 39.44%, 17.36%, and 13.06%, respectively. The output contribution rates of HCl_Pi and resin_Pi were only 1.91% and 0.40%, respectively. In the structural equation model, the load factors of phosphorus fertilizer application rate on Fe_Pi, HCl_Pi, NH4OAc_Pi, resin_Pi, organic phosphorus extracted with NH4F (NH4F_Po), NaHCO3_Pi, and NaHCO3_Po were 0.078, 0.077, 0.061, 0.036, 0.018, 0.015, and 0.012, respectively. The load factors of Fe_Pi, NH4OAc_Pi, and HCl_Po on crop phosphorus uptake were 0.355, 0.334, and −0.039, respectively. The above results show that in calcareous soil, Fe_Pi, NH4OAc_Pi, and HCl_Po were the key phosphorus fractions. Among them, Fe_Pi and NH4OAc_Pi were easily consumed when no phosphorus fertilizer was applied, but they can be easily supplemented by phosphorus fertilizer application. However, HCl_Po was available to the crop but was not easily replenished by phosphorus fertilizer application. The high storage contribution rate and low output contribution rate of HCl_Pi fraction were the important reasons for the low efficiency of phosphate fertilizer in the current season. It is suggested that the choice of phosphorus application rate should be based on the storage contribution rate of the key phosphorus fractions.
Effects of dazomet soil fumigation on characteristics of weed community in Codonopsis pilosula seedling cultivated fields
WANG Hongyan, CHEN Yuan, GUO Fengxia, JIAO Xusheng, ZHANG Biquan, LIU Huili
 doi: 10.12357/cjea.20210258
Abstract(42) HTML(13) PDF(4)
The damage caused by weeds in fields affects the growth of Codonopsis pilosula seedlings, and the use of herbicides damages C. pilosula seedlings and has a poor effect. To explore available ways to control weeds in C. pilosula seedling fields in the main production areas of Gansu Province, dazomet was used to fumigate the soil before sowing (F) while using non-fumigated field as the control (CK). The dynamics and differences of weed communities in the seedling fields were systematically studied. The results showed that 1) during seedling cultivation, the similarity in weed community between F and CK fields was 83.3%, and the average WCs between weed communities in emergence stage and seedling growth stage in the fumigated field was 18.9% lower than that in the CK field. Fourteen species of weeds (10 families and 14 genera) occurred in the CK field, of which five (including two annual weeds of Myosoton aquaticum and Setaria viridis, and three perennial weeds of Cirsium arvense, Convolvulus arvensis, and Sonchus brachyotus) were dominant. Five weed species (Polygonum aviculare, S. viridis, S. brachyotus, Malva cathayensis, and Hypecoum leptocarpum) were reduced in the seedling stage of C. pilosula, and three weed species (P. aviculare, Chenopodium glaucum, and H. leptocarpum) were reduced during the whole growth of C. pilosula in the F field, which on an average decreased by 39.8%. 2) Soil fumigation decreased the diversity of primary weed communities in the early stage of C. pilosula seedlings, in which the weed richness index decreased by 0.68, Shannon-Wiener index decreased by 0.50, and Simpson’s index decreased by 0.36. Soil fumigation also reduced the population abundance of malignant weeds and significantly inhibited its regeneration. 3) Soil fumigation significantly reduced the occurrence density of primary weeds, reducing 477 primary weed plants per square meter in early June. In the F field, the density of primary weeds of seven families was less than 5 plants∙m−2, and the distribution was uniform. Among 10 primary weeds in the CK field, Caryophyllaceae had the highest density, and it accounted for 67.6% of the total number of primary weeds in the field, which was significantly higher than that of other weeds. Polygonaceae, Amaranthaceae, and Gramineae accounted for 22.5%, 5.3%, and 2.2%, respectively, while the other six families in total accounted for only 2.4%. The primary amount of Caryophyllaceae, Polygonaceae, and Gramineae weeds was larger in the non-fumigated field. Soil fumigation reduced 143 regenerated weeds per square meter from late June to Oct and, thus, could reduce the density of regenerated weeds. The average weed density and fresh biomass significantly decreased by 89.0% and 77.5%, respectively. It obviously controlled the early sexually reproducing weeds, such as M. aquaticum and Fagopyrum gilesii, and the late perennial facultatively reproducing weeds such as S. brachyotus and Convolvulus arvensis. These results indicate that soil fumigation with 98% dazomet before sowing can effectively control and alleviate the damage caused by weeds in C. pilosula seedling fields. However, the perennial deep-rooted weeds should be controlled early.
An analysis of the spatial effect of agricultural science and technology investment on agricultural eco-efficiency
WANG Chenxuan, YAO Zuowen
 doi: 10.13930/j.cnki.cjea.210214
Abstract(28) HTML(12) PDF(8)
With increasingly severe agricultural pollution, it is important to explore the effects of agricultural science and technology investments on agricultural ecological efficiency to alleviate rural ecological pressure and promote the healthy development of rural areas. This study used a super-efficiency slack-based measure (SBM) model to measure the agricultural ecological efficiency of provinces in eastern, middle, and western China from 2000 to 2018. According to the Moran index, the spatial autocorrelation of agricultural ecological efficiency and agricultural science and technology input were analyzed. The spatial spillover effect and threshold characteristics of the impact of agricultural science and technology input on agricultural ecological efficiency were explored by using the spatial econometric model. Results showed that from 2010 to 2018, the agro-ecological efficiency was high in the eastern and western regions and low in the middle region. The agro-ecological efficiency in the eastern, middle, and western regions fluctuated significantly from 2000 to 2018, with slight fluctuations in 2000–2003. Agricultural ecological efficiency declined slightly from 2004 to 2008 and then rose slightly from 2008 to 2010. In 2010, the agricultural ecological efficiency was 0.731, after which it declined slightly from 2011 to 2014. From 2015 to 2017, the national agricultural ecological efficiency dropped to 0.5894, 0.5839, and 0.5159, respectively. In 2018, the annual agricultural ecological efficiency increased to 0.5453. The impact of rural science and technology investments on agricultural ecological efficiency presented as an inverted U-shape, and the scale of agricultural science and technology investments had a significant spillover effect on agricultural ecological efficiency. The panel threshold regression showed that the threshold effect of agricultural science and technology investments in the eastern, middle, and western regions in China differed, and that in the eastern region had a positive promoting effect. The positive effect of agricultural science and technology input on agricultural ecological efficiency in the middle region was not as stable as that in the eastern region. The input of agricultural science and technology in the western region harmed agricultural ecological efficiency. The scientific and technological input in the agricultural development of the middle and western regions of China should consider economic and ecological efficiency. Therefore, China should vigorously promote the green and efficient technology mode, actively replace chemical fertilizers with organic fertilizers, accelerate the implementation of scientific fertilizer application techniques, pay close attention on demonstration, fertilizer reduction and fertilization efficiency, and improve agricultural ecological efficiency.
Spatial and temporal variation characteristics of cultivated land in the upper Yellow River from 2002 to 2018 based on time series MODIS
HAN Chunlei, SHEN Yanjun, WU Lanzhen, GUO Ying, CHEN Xiaolu
 doi: 10.13930/j.cnki.cjea.210113
Abstract(31) HTML(7) PDF(5)
The upper reaches of the Yellow River contribute 56.77% of the water resources in the whole basin, while agricultural water in the upper reaches accounts for more than 40% of the whole basin. Using MODIS data with medium-resolution remote sensing and crop phenology data, the cultivated land area in the upper reaches of the Yellow River from 2002 to 2018 was extracted, which provided basic data for studying the impact of cultivated land change in the upper reaches on water resource consumption in the basin. Using Harmonic Analysis of Time Series (HANTS) to smooth the cut and spliced MOD13Q1 data, the NDVI time series curve was easier to identify. Combined with the decision tree classification method and crop growth period and other phenological information, the decision tree rules were compiled, and then the smooth MOD13Q1 data were classified by using the classification rules. The distribution and change of cultivated land in the study area from 2002 to 2018 are obtained. Then, the confusion matrix verification of the extraction results was carried out by using the real ground sample data obtained from field investigation and the county-level statistical data in the study area. The extraction accuracy of cultivated land was above 75%, and R2 reached 0.85. The main results showed that the cultivated land in the study area were increased from 2002 to 2018, with a total increase of 88.21×104 hm2. The most rapidly increased was Ningmeng Irrigation District, the total area of cultivated land in Ningxia increased by 64%, reaching 76.61×104 hm2 in 2018; and Inner Mongolia increased reaching 44.74×104 hm2, accounting for 44% of the total area; and Gansu section increased reaching 18.89×104 hm2; Qinghai section showed an obvious trend of decrease in cultivated land, a total of 5.36×104 hm2. On the whole, the increase rate of cultivated land area is 5.18×104 hm2·a−1, in which the Qinghai section decreases at a rate of 0.2×104 hm2·a−1, the Gansu section increases at a rate of 1.05×104 hm2·a−1, the Ningxia section increases at a rate of 1.87×104 hm2·a−1, and the Inner Mongolia section increases at a rate of 2.46×104 hm2·a−1. Mann-Kendall analysis method was used to analyze the trend of NDVI change in the study area, and it was found that NDVI showed an increasing trend. In addition, compared with the change of precipitation, it also showed an increasing trend. Then using stepwise regression analysis to analyze the selected main indicators, the residents’ disposable income was the main factor affecting the change of cultivated land. Finally, using the collected data for qualitative analysis, it was concluded that water resources policy and engineering facilities construction are the factors affecting the change of cultivated land. The main conclusions of this paper were as follows. The cultivated land in the basin from Longyangxia to Hekou Town in the upper reaches of the Yellow River shows an increasing trend. The medium-resolution MODIS data can be used to extract the cultivated land in the upper reaches of the Yellow River. Water resources policy and local socio-economic environment change were the main driving factors for the change of cultivated land area in the study area.
Effect of intercropping on balancing effect of absorption and desorption characteristics of phosphorus in red soil
ZHOU Long, SU Lizhen, WANG Sirui, WANG Ruixue, PU Zhengxian, ZHENG Yi, TANG Li
 doi: 10.13930/j.cnki.cjea.210312
Abstract(35) HTML(9) PDF(20)
The migration and environment effect of phosphorus in soil are affected by its’ adsorption and desorption. Although the excessive application of phosphorus fertilizer causes phosphorus fixation and loss, reasonable intercropping promotes the absorption and utilization and decreases fixation of phosphorus. This study investigated the adsorption and desorption of phosphorus in red soil under intercropping and phosphorus application, it is signicant for promoting the efficient utilization of red soil phosphorus and balancing environmental effects. In this study, a two-factor split-plot block experiment was adopted through field trials, in which the first factor was the planting pattern, namely maize||soybean intercropping and maize monoculture; the second factor was phosphorus application levels: P0 (0), P60 [60 kg (P2O5)·hm−2], P90 [90 kg (P2O5)·hm−2], and P120 [120 kg (P2O5)·hm−2]. This study aimed to explore the effects of intercropping and application of phosphorus on the adsorption and desorption of phosphorus in red soil, and to quantitatively analyze the relative contribution of intercropping and phosphorus application to phosphorus adsorption and desorption by using the structural equation model, and to reveal the key intercropping effect factors on the adsorption/desorption of phosphorus in red soil by using the aggregated boosted tree methods. Results showed that: 1) the Langmuir isothermal adsorption equation was most suitable for fitting phosphorus adsorption in red soil. The adsorption amount of soil phosphorus increased first and then tended toward saturation with the increase in phosphorus concentration in the equilibrium solution, while the adsorption amount of phosphorus decreased gradually with the increase in phosphorus application. 2) Phosphorus adsorption and desorption in red soil were significantly affected by planting pattern, phosphorus application, and the interaction between planting pattern and application of phosphorus (P<0.01). Compared with monoculture, the maize||soybean intercropping increased the adsorption and desorption of phosphorus by 22.9% and 9.2%, respectively (P<0.05). Under four application rates of phosphorus, compared with monoculture, the adsorption of phosphorus in intercropping increased significantly by 13.0%, 19.4%, 41.5%, and 23.9% (P<0.05), respectively. The desorption of phosphorus increased significantly by 90.2% and 194.4% in P0 and P60 intercropping (P<0.05), but decreased by 52.1% and 34.1% in P90 and P120 intercropping, respectively (P<0.05). 3) Under different planting patterns and phosphorus application levels, the adsorption of soil phosphorus had a significant negative correlation with soil pH, organic matter, resin phosphorus, available phosphorus, total phosphorus, and degree of phosphorus saturation (P<0.01), and a significant positive correlation with free iron oxide, free alumina, and phosphate sorption index (P<0.01). However, the desorption of phosphorus from red soil had a significant negative correlation with a standard phosphorus requirement (P<0.01). The adsorption and desorption of phosphorus in the red soil were mainly affected by pH, organic matter, and free iron oxide. Intercropping of maize and soybean changed soil pH and contents of organic matter and free iron oxide, resulting in differences in the phosphorus adsorption and desorption from that of maize monoculture in red soil, improving the soil phosphorus buffering capacity. At a low phosphorus level, intercropping can accelerate a large amount of phosphorus desorption for plants to absorb and utilize; at high phosphorus levels, intercropping can promote phosphorus adsorption and effectively slow down the loss of phosphorus.
Research status and application prospects of combined nitrogen fixation in gramineous plants
HU Mengyuan, LI Yaying, GE Chaorong, ZHANG Yingying, YAO Huaiying
 doi: 10.13930/j.cnki.cjea.210317
Abstract(23) HTML(19) PDF(6)
Nitrogen is one of the most important factors restricting agricultural production. With the development of artificial nitrogen fixation technology, the application of nitrogen fertilizers can increase crop yields and solve problems related to the fulfilment of the basic human needs of food and clothing. However, it has also caused environmental problems, such as soil compaction, acidification, nitrogen loss, and greenhouse gas emissions (e.g., nitrous oxide, N2O). Compared with synthetic ammonia, biological nitrogen fixation is a green and economical nitrogen fixation method, which entails symbiotic nitrogen fixation and non-symbiotic nitrogen fixation (autogenous nitrogen fixation and combined nitrogen fixation, respectively). Annually, biologically fixed nitrogen can account for more than 50% of the total fixed amount. Compared with symbiotic nitrogen fixation, non-symbiotic nitrogen fixation exists in many plants, for example, sugarcane, rice, maize, wheat, and other gramineous crops that carry out non-symbiotic nitrogen fixation (combined nitrogen fixation). This article reviewed the species of combined nitrogen-fixing bacteria in gramineous plants and their mechanism of action and nitrogen-fixing activity and regulation methods, as well as the resources and applications of these combined nitrogen-fixing bacteria. Compared with symbiotic nitrogen fixation, combined nitrogen-fixing bacteria are more vulnerable to indigenous microorganisms. Research on combined nitrogen-fixing bacteria is more difficult owing to the influence of environmental factors, such as nitrogen levels. It is necessary to screen and purify more combined nitrogen-fixing bacteria to provide optimum materials for research into the nitrogen fixation mechanism. Appropriate levels of nitrogen, phosphorus, molybdenum, iron, and other fertilizers can promote the nitrogen fixation efficiency of bacteria. Nitrogen-fixing bacteria not only increase the extent of soil nitrogen fixation but also facilitate the regulation of plant root hormones, thereby increasing plant disease resistance and stress resistance, promoting healthier plant growth. Finally, agronomic management measures for combined nitrogen fixation through gramineous plants and the practical application of the nitrogen-fixing bacteria are proposed to provide a theoretical basis for improving the efficiency of combined nitrogen fixation through gramineous plants and to promote the application of the nitrogen-fixing bacteria in agricultural production.
Actuality and factors influencing farmer adoption of mechanized harvesting in typical maize ecoregions
GUO Yinqiao, XU Wenjuan, WANG Keru, CHAI Zongwen, XIE Ruizhi, HOU Peng, MING Bo, LI Shaokun
 doi: 10.12357/cjea.20200807
Abstract(8) HTML(6) PDF(2)
To understand the current situation and limiting factors of application of mechanical harvesting of maize, and improve the mechanization level of whole process of maize production in China, this paper investigated the adoption of mechanical harvesting of maize in the main maize planting ecological regions (Helongjiang and Jilin in Northeast region, Xinjiang in Northwest region and Henan in Huanghuaihai region) through questionnaire survey. The influencing factors of adoption of mechanical harvesting, key problems in different regions and of different maize producers (farmers, cooperatives and agricultural technicians) were discussed. The results showed significant differences among regions in the use of mechanical harvesting of maize; the proportion of area where mechanized harvesting was used was highest in Heilongjiang and Xinjiang, with a >83.11% adoption rate. The adoption rate of Henan was 54.72% and that of Jilin was 21.51%, which was the lowest. Mechanized kernel harvesting was largely used in Xinjiang and in some farms in Heilongjiang Agricultural Reclamation, which was mainly due to the large planting scale (>6.67 hm2), harvest convenience, and low cost. Mechanized ear harvesting and threshing after drying was the main form of maize harvesting in Youyi Farm of Heilongjiang Agricultural Reclamation, most areas in Heilongjiang, and part of Huanghuaihai. Factors limiting the application of mechanized kernel harvesting in these areas included unsuitable maize cultivars for mechanical harvesting, no professional kernel-harvesting machine, drying-storage needed for immature grains. However, in these area, the time- and labor-saving and harvested ears easily to be store promoted farmers to adopt mechanized ear harvesting. In Jilin and some areas with small planting scale, artificial harvest still was used due to scattered block and strong habit of traditional practices. Farmers with higher incomes, fixed occupation, ancillary revenue, or agricultural implements were willing to adopt mechanized harvesting. Small farmland, low planting benefit and low family income were the main reasons for the low adoption rate of mechanized harvesting in the investigated regions. The investigation results suggested that planting area, ratio of maize revenue to family income, years using mechanized ear harvesting, marketing ways significantly influenced the diffusion and extension of mechanized harvesting technology. Further expansion of planting area and facilitating direct-selling of grains after harvest will highly significantly affect the behavior of farmers adopting mechanized kernel harvesting. To sum up, the scale and benefit of cultivated land management is the key to the implementation of maize mechanical harvesting technology. The government, scientific institutions and enterprises should strengthen cooperation according to local conditions, and give assistance and guidance from policy, technology, economy and concept, gradually improve the harvest efficiency and the whole mechanization level of maize in China.
Changes in and influencing factors of crop coefficient of winter wheat during the past 40 years on the Taihang Piedmont Plain
LI Haotian, LI Lu, YAN Zongzheng, GAO Congshuai, HAN Linna, ZHANG Xiying
 doi: 10.13930/j.cnki.cjea.210342
Abstract(48) HTML(6) PDF(17)
The crop coefficient (Kc) is defined as actual evapotranspiration (ET) under sufficient water supply divided by the reference crop ET (ET0), which can be calculated using meteorological factors. The Kc is used as a basic parameter to calculate the crop water requirements. The accurate determination of Kc plays an important role in optimizing irrigation management. The Kc changes with crop growth and environmental conditions. The purpose of this study was to assess how Kc varied with crop production and weather conditions by using a long-term field experiment of field management measures of winter wheat. The actual ET of winter wheat under sufficient irrigation and ET0 derived from daily meteorological parameters at Luancheng Agro-ecosystem Experimental Station of the Chinese Academy of Sciences from 1980 to 2020 were used to calculate the seasonal Kc. Additionally, the dominant factors affecting the Kc of winter wheat under the current production conditions were identified from experimental data of three recent years (2017–2020). The results showed that for winter wheat with sufficient water supply from 1980 to 2020, the average ET and ET0 were 434.7 mm and 550.8 mm, respectively. The ET0 was relatively stable, and the ET increased by 17.6%. The average Kc was 0.80 during the past four decades, with an average value of 0.76 in 1980–1990, 0.80 in 1991–2000, 0.81 in 2001–2010, and 0.84 in 2011–2020, indicating a continuously increasing trend. In the past four decades, the yield of winter wheat had increased by 42.4%, and Kc had increased by 11.6%. The increase in ET was the main reason for the increase in Kc. The ET during the past four decades increased with increasing crop production, and with a relatively stable ET0, the Kc increased. Therefore, the Kc varied with changes in crop grain production, which was related to biomass production and canopy size. Under the current growing conditions, leaf area index and biomass were important factors that affected Kc. When the leaf area index reached a certain level, Kc was mainly affected by the atmospheric evaporation potential determined by the saturated water vapor pressure difference and atmospheric temperature. The Kc during the recent three years was 0.79 for 2017–2018, 0.86 for 2018–2019, and 0.79 for 2019–2020. The average ET was 442.3 mm during the three years, and the average Kc at different growing stages of winter wheat were 0.70 from sowing to winter dormancy, 0.42 during winter dormancy, 0.76 from recovery to jointing, 1.18 from jointing to heading, 1.39 during heading to grain-fill, and 0.96 during maturity. Thus, the water requirements for winter wheat after winter dormancy increased sharply and reached the highest values during the heading to earlier grain-filling stages. The results from this study indicate that Kc varies with changes in the crop growing conditions and should not be taken as a constant value. Kc developed during three recent seasons in this study could be used to determine the crop water requirements for irrigation scheduling under the current growing conditions.
Suitability analysis of remote sensing monitoring methods for grassland vegetation growth
RAO Xinyu, LI Hongjun, ZHANG Shengwei, LUO Meng, LIU Zhiqiang, ZHANG Jingwen
 doi: 10.12357/cjea.20210280
Abstract(47) HTML(10) PDF(20)
The research and application of grassland vegetation growth monitoring methods have important scientific significance and application value for the sustainable use of grassland resources and the improvement of the ecological environment. Remote sensing monitoring has characteristics such as high timeliness and wide coverage, and several remote sensing monitoring methods have been increasingly used in crop growth monitoring. As the monitoring objects are all plants, these monitoring methods were tried to introduce to monitor grassland vegetation growth in this study. We applied four remote sensing monitoring methods for the crop growth: direct monitoring, vegetation growth process curve, same period comparison, and NDVI percentiles to the grassland vegetation growth monitoring of West Ujimqin County in Inner Mongolia; to clarify the suitability and limitation of these remote sensing monitoring methods for crop growth when monitoring grassland vegetation growth using MODIS Vegetation Index Products (NDVI). The monitoring results provided by the direct monitoring method and the NDVI percentile method were compared with the ground sampling data. The direct monitoring method could intuitively reflect the spatial heterogeneity of grassland vegetation growth by the grassland NDVI, and the NDVI value was significantly correlated with the dry weight of grassland yield per unit area (R2=0.5502). However, this method could not provide details on the growth of different types of grasslands owing to the limitation of the NDVI grade. The vegetation growth process curve method could only collectively reflect the changes in the overall growth of the grassland in the monitored area over time, showing that the growth was better or worse than that of the reference year. In this study, the NDVI peak values of the vegetation growth process curves for the meadow grassland and typical grassland were 0.73 and 0.55, respectively, significantly different from the whole regional lumped monitoring results (NDVI peak value was 0.60). This means that different grassland types should be monitored separately to reflect their respective growth processes. For the same period comparison method, if the selected reference year was different, the method would provide different monitoring results for grassland growth; the results from grassland growth monitoring were semi-quantitative comparative. Using the statistical analysis of NDVI data of different grassland types for 5 years, the NDVI percentile method could quantitatively evaluate the growth of corresponding grassland types, as shown in this study. The determination coefficient of the correlation between the growth score provided by the NDVI percentile method and the dry weight of grassland yield per unit area was 0.5047. To achieve a reasonable classification of these semi-quantitative monitoring results of grassland growth, the assistance of ground grassland monitoring information is required. There is an urgent need to establish a sky-air-ground integrated grassland growth monitoring platform to improve the efficiency and accuracy of grassland vegetation growth monitoring.
Quantification planting density based on heat resource for enhancing grain yield and heat utilization efficiency of grain mechanical harvesting maize
YU Shengnan, GAO Julin, MING Bo, WANG Zhen, ZHANG Baolin, YU Xiaofang, SUN Jiying, LIANG Hongwei, WANG Zhigang
 doi: 10.12357/cjea.20210231
Abstract(25) HTML(7) PDF(16)
The selection and promotion of mechanical grain harvesting maize varieties that shorten the maturity period in exchange for sufficient dehydration time pose new challenges for increase in the yield of spring maize in the north and the full utilization of heat. The use of a synergistic mechanism can provide a theoretical basis for the high-yield and high-efficiency cultivation and large-scale promotion of mechanically grain-harvested varieties of maize. In this study, different types of maize varieties were used as the tested materials, and the density network tests were conducted in four ecological regions of Inner Mongolia with different thermal conditions in eastern Inner Mongolia, which belonged to heat limt area (where medium-early- and early-maturing maize varieties are planted) and heat sufficient area (where the medium-later- or late-maturing varieties are planted), respevtively. The effects of planting density on stage development, yield formation, and heat use efficiency (HUE) of different types of maize varieties were analyzed, and their responses to heat resources were analyzed. The results showed that the maximum yield of mechanical grain-harvesting varieties was obtained under the condition that the accumulated temperature utilization rate of ≥10 ℃ reached 86.0%~89.3%. The maximum yield and corresponding density of mechanical grain-harvesting varieties in different regions were higher than those of the current famers’ variety, especially the differences were obvious in the regions with limited heat. The density of the maximum yield of mechanical grain-harvesting varieties decreased linearly with the increase of the total amount of heat resources. The density increased by 1700 plants·hm−2 for every 100 ℃ decrease of accumulated temperature in the region ≥10 ℃. The areas with limited heat (ecological areas dominated by early-maturing and early-maturing varieties, in this paper, it is east region of Xing’an Mountain and south region of Xing’an Mountain), The proportion of growing days per-silking and post-silking, the proportion of accumulated temperature ≥10 ℃, and the proportion of biomass of mechanical grain-harvesting varieties all approached 5∶5. To achieve the maximum yield, it was necessary to increase the densification from 60000 plants·ha−2 to 88,000−91,000 plants·hm−2. Increases the density after increasing yield of 11.1 t −12.7 t·hm−2, yield increase 20.1%−23.3%, and HUE can be increased by 20.6%−30.1%; In areas with abundant heat (ecological areas mainly planted with mid-late maturity or late maturity varieties, this paper refers is the north region of Yanshan Mountain and west Liao River Plain), The ratio of growing days and accumulated temperature per-silking and post silking tended to be 4.5:5.5, the ratio of biomass at per-silking and post silking was 4:6, and the yield ranged from 15.4 to 16.9 t·hm−2. The maximum yield needed to be densified from 60000 plant ·ha−2 to 81,000-83,000 plant ·hm−2. After densification, the yield can be increased by 6.1%−11.5%, and the HUE can be increased by 8.6%−17.5%. The effective matching of heat demand of varieties and regional heat resources is the premise to obtain high yield and fully tap the potential of regional yield. Quantitative dense planting based on the matching of heat resources is an effective way to achieve increased yield and efficient utilization of heat resources for mechanical grain-harvesting varieties of spring maize. In the area with limited heat resources, the balance of pre – silking and post-silking at resources and the full accumulation of pre – silking biomass were the key factors, and the suitable density was 88,000 to 92,000 plants·hm-2. In the area with abundant heat, the production of post-silking matter was explored, and the suitable density population was constructed. The miaze was to delay post-silking leaf senescence, and the suitable density was 81,000-83,000 plants·hm−2.
The spatiotemporal change characteristics of the safe growth period and the high temperature damage of ratoon rice in nine southern provinces of south China
DUAN Licheng, GUO Ruige, CAI Zhe, LIN Zhijian, WU Ziming, FANG Sheng, ZHANG Chonghua, LIU Dan
 doi: 10.12357/cjea.20210244
Abstract(23) HTML(17) PDF(6)
In the context of global warming, with the increasing cultivated area of ratoon rice, ensuring the sowing of ratoon rice to safe maturity is of particular importance for making full use of temperature and sunlight resources and stabilizing the production of ratoon rice, as well as ensuring food security. Made clear the spatiotemporal change characteristics of safe sowing date, duration from safe sowing date to safe full heading date (safe growth period) and high temperature damage, this study could provide insight to make full use of temperature and light resources, and safety production under global warming. Based on daily average temperature data during the past 39 years (1981-2019) collected from 601 weather stations in nine southern provinces (nine southern provinces in the south, including Sichuan, Chongqing, Hubei, Hunan, Jiangxi, Anhui, Jiangsu, Zhejiang, Fujian), our study analyzed the change characteristics of safe sowing date and safe growth period, and high temperature damage of ratoon rice by using methods of climate tendency rate and mutation analysis in nine southern provinces. The results showed that the safe sowing date had advanced 3.3days·(10 a)−1, the safe full heading date had retarded 1.5days·(10 a)−1, and the safe growth period had extended 4.8days·(10 a)−1. The safe sowing date mutation occurred in 2001, and the mutation occurred 9 days earlier than the mutation prerequisite. The safe growth period mutation occurred in 1996, which was 12 days longer than before. The safe sowing date was earlier in the south than in the north, and the safe growth period in southeast extended more obvious than in northwest. The high temperature damage presented a trend of increase in June - July and August – September. The mild, moderate, and severe damage had increased 48.5 stations∙(10a)−1, 30.3 stations∙(10a)−1, 37.4 stations∙(10a)−1 in June and July, and 52.7 stations∙(10a)−1, 18.2 stations∙(10a)−1, 34.6 stations∙(10a)−1 in August and September respectively, and the high temperature damage in June - July was more serious than in August and September. The annual average number of stations with mild, moderate and severe high temperature damage occurred in June and July were 83.9 stations, 41.6 stations and 115.9 stations respectively, which was more than August and September. The mutational years of mild, moderate and severe high temperature damage were 1998, 1988, 1986 in June and July, and 1992, 2002, 2002 in August and September, and the high temperature damage increased significantly after the mutation. The occurrence of high temperature damage stations were mild > severe > moderate in June and July as well as August and September. Advancement of safe sowing date and extension of safe growing period of ratoon rice were beneficial to make full use of temperature and light resources, and increase yield in nine provinces of South China. However, the increase of the high temperature damage was not conducive to high quality and high yield of ratoon rice.
Low carbon development strategy for agriculture based on cybernetics
LUO Shiming
 doi: 10.12357/cjea.20210583
Abstract(16) HTML(7) PDF(5)
Agriculture is an agroecosystem with a cybernetic system nature. The low-carbon development of agriculture falls into the category of eco-friendly eco-agriculture. Human direct regulation methods for the low-carbon development of eco-agriculture originate from the exploration of traditional and local farmers, modern interdisciplinary agricultural research, and eco-friendly high-tech industries. To get low-carbon goals, the methods from different sources, which are conducive to adapting and strengthening the natural regulation process, can be investigated for their compatibility, synergy and effectiveness within a specific system. The selected methods can be synthesized and optimized to help form a diversified low-carbon system and a suitable technical package. The top-down stimulation measures introduced by the government and the bottom-up efforts provided by people constitute the human indirect regulation for agroecosystems. These entities need to cooperate to form a social joint force to effectively accelerate the low-carbon development of eco-agriculture to reach the national goal of carbon neutralization.
Comparison of two monitoring methods for ammonia volatilization based on rice-wheat rotation system
WANG Yuan, MIN Ju, SHI Peihua, MA Mingkun, HAO Yaqiong, SHI Weiming
 doi: 10.13930/j.cnki.cjea.210210
Abstract(22) HTML(6) PDF(10)
Ammonia volatilization is an important pathway of active nitrogen (N) loss from farmlands. The accurate and effective measurement of farmland ammonia emissions is the basis for environmental assessments and policymaking. Soil ammonia volatilization is controlled by fertilizer application rates, fertilizer application methods, soil properties, and meteorological conditions, so there is a wide variability in the cumulative ammonia emissions and emission factors in different studies. There are also different methods for ammonia volatilization measurements, which further reduce the comparability of data across studies. The most widely used methods for soil ammonia volatilization measurements in China are the ventilated sponge absorption method and the intermittent airflow enclosure method. However, consistency between measurements is unclear because of substantial differences in the ventilation rates between methods, and only a few studies have compared the two methods. Based on a typical rice-wheat rotation system in the Lower Reaches of the Yangtze River, this study set up treatments with different N fertilizer application rates (N0: no N fertilizer; N1: 200 kg(N)·hm−2 for rice and 180 kg(N)·hm−2 for wheat; N2: 300 kg(N)·hm−2 for rice and 270 kg(N)·hm−2 for wheat; and N3: 400 kg(N)·hm−2 for rice and 360 kg(N)·hm−2 for wheat). Soil ammonia volatilization was measured continuously after fertilization during rice and wheat growth using the ventilated sponge absorption and intermittent airflow enclosure methods, and the ammonia emission factors in the study area were analyzed using literature analysis. The results showed that the cumulative ammonia emission measured by the ventilated sponge absorption method was 25%–35% lower than that measured by the intermittent airflow enclosure method under the three N application treatments (except for the N0 treatment), and the results were consistent for both rice and wheat seasons. Under fertilization treatments (N1, N2 and N3), the cumulative ammonia emissions measured by the ventilated sponge absorption method ranged from 17.36 to 43.90 kg·hm−2 in the rice season and from 5.90 to 20.43 kg·hm−2 in the wheat season, with emission factors ranging from 2.56% to 10.39%. The cumulative ammonia emissions measured by the intermittent airflow enclosure method ranged from 23.28 to 61.05 kg·hm−2 in the rice season and from 14.63 to 27.73 kg·hm−2 in the wheat season, with emission factors ranging from 7.09% to 15.01%. The cumulative ammonia emissions under the N0 treatment were higher for the ventilated sponge absorption method than for the intermittent airflow enclosure method, and the measurements of the two methods were significantly different in the rice season but not in the wheat season. The results of the literatures analysis in the study area were consistent with the monitoring results. The cumulative ammonia emissions measured by the ventilated sponge absorption method were higher than those measured by the intermittent airflow enclosure method when the N application rate was between 0 and 100 kg·hm−2, with average emission factors of 6.18% and 12.31%, respectively. When the N application rate was between 101 and 200 kg·hm−2, the ventilation sponge absorption method led to 25% lower emissions than the intermittent airflow enclosure method, with average emission factors of 9.46% and 12.61%, respectively. When the N application rate was between 201 and 300 kg·hm−2, the ventilation sponge absorption method led to 5% lower emissions than the intermittent airflow enclosure method, and the average emission factors were 12.71% and 13.43%, respectively. In general, the cumulative ammonia emissions measured by the two methods were consistent; the ventilated sponge absorption method led to higher measured values than the intermittent airflow enclosure method in fields without N application or with low ammonia volatilization rates, and the ventilated sponge absorption method led to lower measurements than the intermittent airflow enclosure method in fields with N application. The measurements of the two methods can be converted using a ratio. The results of this study provide support for the estimation of regional ammonia emissions using the ventilated sponge absorption and intermittent airflow enclosure methods.
Research progress on the wheat powdery mildew resistance gene Pm2
JIN Yuli, GU Tiantian, LIU Hong, AN Diaoguo
 doi: 10.13930/j.cnki.cjea.210279
Abstract(36) HTML(5) PDF(4)
Wheat (Triticum aestivum L.) is an important crop in China, high and stable yields are crucial for ensuring food security. Powdery mildew caused by Blumeria graminis f. sp. tritici. Bgt is a devastating disease of wheat. Chemical and agricultural control methods are used to prevent powdery mildew, but utilizing host resistance may represent a more economical, environmentally friendly, and effective method to control the epidemic of powdery mildew. The powdery mildew resistance gene Pm2, located on the short arm of chromosome 5D, encodes a CC-NBS-LRR protein and is one of the most widely used Pm genes in wheat powdery mildew resistance breeding because of its excellent resistance and desirable agronomic traits. In this review, the recent progress in Pm2 research and utilization in wheat breeding is systematically summarized in terms of the following aspects: identification and characterization of Pm2 , exploration and utilization of the alleles at the Pm2 locus, gene cloning, development of functional markers, haplotype analysis, AvrPm2 gene cloning, and the applications in wheat breeding programs. It has been proposed that: 1) the differences in the resistance of different Pm2 alleles may be caused by diverse genetic backgrounds, other regulatory factors in the disease resistance pathway, or the highly heterozygous state of Bgt isolates. 2) The powdery mildew resistance gene Pm2 should be reasonably distributed and utilized in disease resistance breeding to prolong the service life of disease resistance genes and increase durability. 3) Essential methods to control the epidemic of powdery mildew should include mining and utilizing novel resistance genes and allelic variations and strengthening the innovation of new wheat germplasms. This review aimed to provide a theoretical basis for further work on the resistance mechanism of Pm2 and to accelerate its application in wheat powdery mildew resistance breeding.
The effects of nitrogen fertilizer deep placement on the ammonia volatilization from paddy fields in the Taihu Lake region of China
WANG Shuwei, LIN Jinghui, WU Zhenggui, CHEN Ji, PAN Yunjun, SHENG Xuewen
 doi: 10.13930/j.cnki.cjea.210119
Abstract(77) HTML(17) PDF(29)
.Ammonia (NH3) volatilization is an important nitrogen (N) loss pathway in paddy fields. However, the effects of N fertilizer deep placement, slow-release N fertilizers, and urea inhibitors on NH3 volatilization reduction during the entire rice-growing season remain uncertain. To fill this knowledge gap, we conducted a field experiment with seven treatments: (1) no N application, (2) local broadcasting application of urea at a rate of 300 kg(N)∙hm−2 (SN300), (3) 10% reduction of N from SN300 (SN270), (4) deep placement of basal urea together with the broadcasting of topdressing of urea at tiller and panicle stages of rice, at a total a rate of 270 kg(N)∙hm−2 (DN270), (5) application of urea inhibitor for DN270 (DN270+UI), (6) 10% nitrongen reduction deep application of basal urea together with the surface application of slow-release N fertilizer (DN270+SR), and (7) application of urease inhibitors for DN270+SR (DN270+SR+UI). Compared with the SN300 treatment, deep placement of basal N fertilizer reduced the cumulative NH3 emissions by 78.2%−85.2% in the basal fertilization period. The combined application of the urease inhibitors in the rice topdressing periods (DN270+UI treatment) reduced the NH3 emissions by 30.4% at the tillering stage and 25.3% at the panicle stage in comparison with the SN300 treatment. Replacing urea with a slow-release N fertilizer (DN270+SR treatment) in the rice topdressing peirods reduced NH3 volatilization by 36.4% at the tillering stage and 28.1% at the panicle stage. The cumulative NH3 volatilization changed in the following order: SN300 > SN270 > DN270 > DN270+UI > DN270+SR > DN270+SR+UI. Compared to the local treatment (SN300), DN270+SR+UI significantly reduced NH3 volatilization by 50.9%. There was no significant difference in rice yield among the N fertilizer treatments. NH3 emission intensity per unit rice yield was lowest for the DN270+SR+UI treatment, 52.5% lower than the SN300 treatment. Overall, simultaneous N fertilizer deep placement with slow-release N and urease inhibitors produced more grains with lower environmental costs associated with NH3 emissions. This represents a promising and sustainable management strategy for paddy fields in the Taihu Lake region of China.
Effects of different water and nitrogen management on ammonia volatilization in pear orchard soil
XING Hanbing, DONG Wenxu, PANG Guibin, HU Chunsheng
 doi: 10.13930/j.cnki.cjea.210133
Abstract(34) HTML(4) PDF(13)
Before the pear tree fertilization and management of blind and extensive, resulting in fertilizer waste and ecological environment and other problems.Making full use of soil water and fertilizer to improve crop yield is the long-term goal of farmland managers.In this paper, the changes of soil ammonia volatilization rate, loss and physical and chemical properties under different water and nitrogen management in pear topdressing period were analyzed by dynamic box method in orchard demonstration base of Jinzhou City, Hebei Province from March to September 2019.The experiment set up 5 treatments: blank (CK), surface spraying conventional irrigation (BW1), injection fertilization routine irrigation (IW1), surface spraying water saving irrigation (BW2), injection fertilization water saving irrigation (IW2).The volatilization of ammonia in each treatment was the most severe in the first 4 d. The two treatments (BW1、BW2) were especially severe. The peak variation range was 1.5−7.5 kg·hm−2·d−1, while the two injection treatments (IW1、IW2) changed steadily with time. The peak range was 0.1−5 kg·hm−2·d−1.The volatile loss of ammonia BW1、IW1、BW2、IW2 treatment was 24.05 kg·hm−2, 8.43 kg·hm−2, 31.94 kg·hm−2and 14.06 kg·hm−2, compared with BW1 (traditional management), and the emission reduction rates of injection fertilization (IW1 and IW2) was 64.95% and 41.54%, respectively. Ammonia volatilization was significantly affected by irrigation amount, and rhizosphere injection fertilization could significantly reduce ammonia volatilization emission and was less affected by irrigation amount.The correlation analysis showed that ammonia volatilization was positively correlated with the content of ammonium nitrogen and soil pH, but negatively correlated with the content of nitrate nitrogen, and the correlation between ammonium nitrogen and nitrate nitrogen was extremely significant (P<0.01). Soil moisture was positively correlated with ammonium nitrogen at a significant level (P<0.01).Compared with traditional management methods, the combination of rhizosphere injection fertilization and water-saving irrigation is one of the effective ways to reduce nitrogen loss in orchards.
Agroecosystem and Its Management
Progress and perspective in research on plant resistance mediated by root exudates
MAO Mengxue, ZHU Feng
2021, 29(10): 1649-1657.   doi: 10.13930/j.cnki.cjea.210328
Abstract(212) HTML(37) PDF(108)
Root exudates are a variety of biochemical substances actively or passively secreted by plant roots that play an important role in mediating material exchange, energy transfer and information exchange in plant rhizosphere microenvironments, as well as in plant responses to environmental stresses. Biotic and abiotic stresses can change the composition and quantity of root exudates and increase the content of defensive compounds in plant root exudates. Plants use different root exudates to resist biotic and abiotic stresses, including releasing toxic substances for direct defense, releasing volatile substances to attract natural enemies, interacting with microorganisms to resist biotic stresses, releasing root exudates with osmotic regulation and antioxidant capacity and coordinating hormone signals to resist abiotic stress. Additionally, root exudate flow increases the concentration of many common metabolites, changing the soil physical and chemical properties and microbial activities, and affecting the physiological and biochemical processes at the soil-plant interface, thereby, directly or indirectly improving plant stress resistance. In this paper, the effects of biotic and abiotic stresses on the composition and quantity of plant root exudates were reviewed, the mechanisms of plant defense against biotic and abiotic stresses mediated by root exudates were summarized, and the aspects needed to be further studied were also suggested, to provide a reference for further research on the adaptive mechanism of plants under stress.
Characteristics and environmental effects of nitrogen flows in the crop-livestock system of Jiangsu Province
YU Le, JIAO Yangmei, DING Shang, ZHU Zhiqiang, ZHAO Hongwei
2021, 29(10): 1658-1667.   doi: 10.13930/j.cnki.cjea.210172
Abstract(70) HTML(32) PDF(43)
With the rapid development of agriculture and animal husbandry, large nitrogen inputs have caused a series of environmental problems. To provide a scientific reference for regional nutrient management, Jiangsu Province, an economically developed region in the Yangtze River Delta, was selected to study the nitrogen flow characteristics in crop-livestock systems from 1998 to 2018 and their environmental effects. The research was based on the NUFER model (NUtrient flows in Food chains, Environment and Resources use, NUFER) and incorporated statistical yearbook data, survey data, and literature data. The nitrogen account balance, nitrogen use efficiency, nitrogen recycling, and loss of the crop-livestock systems in Jiangsu Province were quantitatively analyzed, and the relationships between the economy, resources, and environment of the crop-livestock systems were explored based on a structural equation model. The results showed that from 1998 to 2018, the crop subsystem increased the amount of nitrogen carried by the crop products under the gradual decrease of the total nitrogen imports of the subsystem. Nitrogen carried by the main crops and crop by-products increased from 8.31×105 t to 1.20×106 t. Total nutrient loss also declined. For the livestock-poultry subsystem, nitrogen was mainly introduced via exogenous and local feed; exogenous feed was the main source of nitrogen in the subsystem. The proportion of local feed nitrogen supply increased annually, from 29.32% in 1998 to 44.77% in 2018. From 1998 to 2018, the nitrogen use efficiency of the crop-livestock system increased from 21.39% to 35.00%. The amount of straw to field, local feed, and manure to field increased annually, and the total amount of recycled nitrogen increased from 2.54×105 t to 3.00×105 t. Nitrogen environmental emissions decreased in the past 20 years, and the main sources of loss included soil nitrogen surplus, gas emission loss, water discharge loss, and manure residue. The structural equation model results showed that in the developmental process of the agricultural and animal husbandry systems in Jiangsu Province, economic development and resource reduction promoted improvements in product output and system efficiency. Under the guidance of regional development and policies, crop-livestock systems in Jiangsu Province developed rapidly from 1998 to 2018. The scale of the agricultural and animal husbandry systems had continuously expanded, resource utilization had been relatively efficient, and environmental emissions had gradually decreased. However, there was also a slight imbalance in the development of crop-livestock systems, and there were relatively few combinations of crop-livestock. Future development of the agriculture and animal husbandry systems in Jiangsu Province should focus on coupling the crop and animal husbandry subsystems, moderately expanding the production scale, and balancing the development of agriculture and animal husbandry subsystems to promote local agriculture and animal husbandry.
Spatio-temporal variation in and the driving factors of desert vegetation in Xinjiang
CUI Can, GUO Ying, SHEN Yanjun
2021, 29(10): 1668-1678.   doi: 10.13930/j.cnki.cjea.210121
Abstract(66) HTML(21) PDF(28)
Desert vegetation is an important part of arid and semi-arid ecosystems in Xinjiang and plays a key role in the maintenance of ecosystem balance. Timely and accurate monitoring of the temporal and spatial distribution of desert vegetation is important for the sustainable utilization of the resources and ecological restoration. Based on remote sensing technology combined with two Normalized Difference Vegetation Index (NDVI) products (AVHRR-NDVI and MOD13A2-NDVI), the area of desert vegetation in Xinjiang from 1989 to 2017 was estimated. The temporal and spatial characteristics of desert vegetation in three typical river basins (Ulungur River Basin, Aksu River Basin, and Yarkand River Basin) were analyzed, and the relationships between desert vegetation and the climate factors, runoff changes, and policy factors were discussed. The NDVI products were used to calculate the vegetation coverage ( fc), and the distribution and area of desert vegetation were determined according to the threshold of vegetation coverage. Desert vegetation was determined within the fc threshold range of 0.1–0.35, where 0.1–0.25 indicates low-coverage desert vegetation and 0.25–0.35 indicates high-coverage desert vegetation. The transformation between desert vegetation and other vegetation types was calculated using the land use transfer matrix to explore the evolution and transformation of desert vegetation in Xinjiang from 1989 to 2017. The driving factors of desert vegetation evolution in the three typical river basins were analyzed using correlation analysis. The results showed that the total area of desert vegetation in Xinjiang significantly increased from 1989 to 2017 at a rate of 30 900 hm2∙a−1. The area of low-coverage desert vegetation significantly increased at a rate of 32 200 hm2∙a−1; whereas the area of high-coverage desert vegetation did not vary, with a multi-year average value of 2 087 100 hm2. The area of desert vegetation in northern Xinjiang increased slightly, accounting for 67% of the total area of desert vegetation. This was mainly due to an increase in low-coverage desert vegetation. The area of high-coverage desert vegetation in northern Xinjiang slighly decreased. The desert vegetation area in southern Xinjiang significantly increased. During vegetation transformation, 508 500 hm2 of desert vegetation transformed from high to low desert vegetation, 3.4124 million hm2 of non-desert vegetation types transformed into desert vegetation, and 1.9125 million hm2 of desert vegetation transformed into non-desert vegetation types. This study of typical river basins showed that the area of desert vegetation increased with increasing precipitation. Precipitation was the most important factor affecting the evolution of desert vegetation, followed by runoff and policy factors. The influence of air temperature on desert vegetation varied across regions, and the area of desert vegetation near water increased with increasing temperature.
Crop Cultivation and Physiological Ecology
Effect of increased plant density with reduced nitrogen on yield formation and nitrogen use efficiency of hybrid rice under high temperature and high humidity conditions
JIANG Peng, XU Fuxian, ZHANG Lin, ZHOU Xingbing, ZHU Yongchuan, GUO Xiaoyi, LIU Mao, CHEN Lin, ZHANG Rong, XIONG Hong
2021, 29(10): 1679-1691.   doi: 10.13930/j.cnki.cjea.210288
Abstract(52) HTML(31) PDF(30)
The effects of increased plant density with reduced nitrogen (N) application rate on yield formation and nitrogen use efficiency (NUE) of hybrid rice were studied to provide a theoretical basis for optimum nitrogen fertilizer management and plant density under high temperature with high humidity conditions. Field experiments were conducted in Luzhou City from 2018 to 2019. The high yield and high quality hybrid rice variety ‘Nei6you107’ was grown under six combinations of plant density and N application rate: 1) locally recommended combination with a plant density of 16.5×104 hills∙hm−2 and a N rate of 180 kg∙hm−2 (LDNck); 2) combination of a plant density of 16.5×104 hills∙hm−2 and a reduced N rate by 15% (153 kg∙hm−2, LDN−15%); 3) combination of a plant density of 16.5×104 hills∙hm−2 and a reduced N rate by 30% (126 kg∙hm−2, LDN−30%); 4) combination of a increased plant density by about 27% (21.0×104 hills hm−2) and a reduced N rate by 15% (153 kg∙hm−2, HDN−15%); 5) combination of a increased plant density by about 27% (21.0×104 hills∙hm−2) and a reduced N rate by 30% (126 kg∙hm−2 HDN−30%); and 6) combination of a plant density of 16.5×104 hills∙hm−2 and zero N rate (LDN0). The grain yield, yield components, dry matter, N uptake and NUE were measured. The results showed that the grain yield of hybrid rice was significantly affected by different combinations of plant density and N rate (P<0.01). HDN−15% and HDN−30% produced higher grain yields than LDNck by 4.3%−4.9% and 2.3%−3.6%, respectively. The higher grain yields under HDN−15% and HDN−30% were attributed to improvement in spikelets per panicle, grain filling rate, translocation of dry matter accumulated at heading stage (TDMHD), translocation percentage of dry matter accumulated at heading stage (TPDMHD), contribution percentage of pre-anthesis dry matter translocation to grain yield (CPDMTGHD) and harvest index. The LDN−15% and LDN−30% had 2.3%−2.5% and 4.8%−5.0% lower grain yield than LDNck, respectively. The yield gap between LDN−15%, LDN−30% and LDNck was attributed to the difference in effective panicles, total dry matter, dry matter accumulation from heading to maturity, and contribution percentage of dry matter accumulation from heading to maturity stage to grain yield (CPDMGHD-MA). The HDN−15% and HDN−30% had lower nitrogen accumulation from heading to maturity and total N uptake than LDNck, whereas the translocation of N accumulated at heading stage (NTGNHD), translocation percentage of N accumulated at heading stage (TPNHD), contribution percentage of pre-anthesis N accumulation translocation to grain N accumulation (CPNTGNHD), N use efficiency for biomass production (NUEBP), N use efficiency for grain production (NUEGP) and N harvest index under HDN−15% and HDN−30% were higher than those under LDNck. Consequently, HDN−15% and HDN−30% had lower N requirements to produce 100 kg of grain (NRPG) than LDNck by 6.8%−8.4% and 9.0%−9.9%, respectively. HDN−15% enhanced the agronomic efficiency of applied N (AEN) by 36.7%−37.4%, partial factor productivity of applied N (PFPN) by 22.8%−23.5% and recovery efficiency of applied N (REN) by 5.6%−12.0% over LDNck. The HDN−30% produced higher AEN, PFPN and REN than LDNck by 55.5%−60.4%, 46.3%−48.2% and 17.0%−20.0%, respectively. The rational combination of plant density and N rate can improve panicle number per unit area, grain filling, TDMHD, TPDMHD, NTGNHD, TPNHD and harvest index, which further increasing the grain yield and NUE. The optimum combination is plant density of 21.0×104 hills∙hm−2 plus N rate of 126−153 kg∙hm−2 in high temperature with high humidity condition.
Effects of fertilizer patterns on the potential nitrogen fixation rate and community structure of asymbiotic diazotroph in highland barley fields on the Tibetan Plateau
MA Ruiping, DAI Xianglin, LIU Guoyi, XIE Yongchun, GAO Xiaoli, GAO Xue
2021, 29(10): 1692-1703.   doi: 10.13930/j.cnki.cjea.210148
Abstract(68) HTML(17) PDF(31)
Free-living nitrogen fixation (FLNF) by diazotrophs is an important nitrogen (N) source in terrestrial ecosystems and may reprensent a viable solution to environmental pollution caused by N over-fertilization. Studying the impact of different fertilizer regimes in highland barley fields on the diazotrophic community profiles and potential N fixation rates (PNFR) may provide scientific fertilization strategies and a theoretical basis for agricultural green development in the Tibetan Plateau. Here, quantitative PCR, high-throughput sequencing and 15N labeling methods were used to better understand the impact of different fertilizer regimes on the abundance and composition of diazotrophs as well as the potential N fixation rates in highland barley fields on the Tibetan Plateau. The experiment included five treatments: a control without fertilizer (CK); N, phosphorus (P) and potassium (K) mineral fertilzers (F); manure fertilizer (M); mineral NPK fertilizers plus manure (FM); and mineral NPK fertilizer plus straw (FS). The results showed that: 1) compared with the CK and F treatments, the M, FM and FS treatments significantly (P<0.05) increased the contents of soil organic carbon (C) and total N. Moreover, the ammonium nitrogen (NH4+-N) content was significantly (P<0.05) higher in the FM treatment than in the other treatments. The highest contents of organic C, total N, nitrate N (NO3-N), available P and available K were observed in the M treatment, and their contents were significantly (P<0.05) higher than those in the other treatments. 2) The PNFR ranged from 2.63 to 4.07 μg∙kg−1∙d−1 under different fertilizer treatments. Fertilization, especially the application of organic fertilizers (sheep manure or straw), reduced the PNFR, and the inhibitory effect of straw on PNFR was higher than that of sheep manure. The soil NH4+-N content was the main factor affecting PNFR. 3) The M and FM treatments significantly (P<0.05) increased diazotrophic abundance, while the opposite was observed for the F and FS treatments. The total N content was the key factor affecting diazotrophic abundance. 4) Different fertilizer patterns significantly changed the diazotrophic composition, and the similarities in the diazotrophic compositions among different fertilizer regimes fell into three major categories: no fertilization (CK), organic fertilization (M), and chemical fertilization (F, FM, FS). Available P was the key factor regulating diazotrophic composition, followed by pH and C/N. In conclusion, the M treatment was the optimal fertilizer practice to improve soil fertility, increase diazotrophic abundance and reduce PNFR decline in highland barley fields on the Tibetan Plateau.
Analysis of mechanical grain harvesting quality and its influential factors of spring maize in Shanxi Province
YAN Xiaoguang, LI Hong, DONG Hongfen, LI Aijun, WANG Guoliang, ZHOU Nan, HU Ying, DU Yanwei
2021, 29(10): 1704-1711.   doi: 10.13930/j.cnki.cjea.210151
Abstract(61) HTML(8) PDF(18)
The study of mechanical grain harvesting quality and its influential factors is significant for popularizing mechanical maize harvesting technology in Shanxi Province and enhancing the core competitiveness of the maize industry. To study the influence of harvest time on the quality and yield of maize mechanically grain harvested, five maize varieties suitable for mechanical harvest were harvested at six times (Septmber 24th, and October 1st, 8th, 15th, 22th and 29th) by the same harvester and driver. The grain moisture content, broken rate, impurity rate, as well as ear loss rate, grain loss rate, total loss rate and yield of maize were investigated. The results were as follows: first, the grain moisture content declined gradually with a delayed harvest time. With a delayed harvest time, the grain broken rate and loss rate decreased rapidly in the early period but was stable and slightly increased in the later period. Furthermore, with a delayed harvest time, the impurity rate declined gradually and tended to be stable at the end. Finally, with a delayed harvest time, the ear loss rate increased gradually. The average yield when the field was harvested on October 15th was 11.9% higher than that harvested on September 24th. The high grain broken is the main factor limiting the quality of mechanical grain harvesting of spring maize in Shanxi Province. The relationship between grain moisture content and broken rate could be fitted in the model y=0.03x2−1.224x+16.78 (R2=0.802**). The grain broken rate was the lowest when its moisture content was 20.4%. When the grain moisture content was between 15.6% and 25.2%, its broken rate was less than the national standard of 5%. Choosing the optimal variety for mechanical harvest in the spring maize area of Shanxi Province and harvesting on October 15th could guarantee harvesting quality and yield. ‘Changdan 511’ ‘Dika 159’ and ‘Changdan 716’, which have both perfect mechanical harvest quality and high yield, could be used as mechanical harvest varieties in the spring maize area of Shanxi Province.
Impact of saline irrigation and application of N and P on growth and nutrient distribution of Tamarix chinensis planted in coastal saline-alkali soil
QIU Fagen, YANG Lilin, LIU Min, ZHU Xiangmei, CHEN Shuling
2021, 29(10): 1712-1721.   doi: 10.13930/j.cnki.cjea.210209
Abstract(37) HTML(6) PDF(15)
Saline irrigation is a highly effective method of elimination of salt and drought stress in spring in the coastal severe saline-alkali soils. Tamarix chinensis, a salt-tolerant plant, plays an important role in reforming the ecological landscape of the coastal wetlands in northern China. However, the responses of plant growing rhythm of T. chinensis to long-term saline irrigation-associated fertilization remain unclear. To promote the rapid growth of T. chinensis for carbon (C) fixation, landscape construction, and saline-alkali soils reclamation, an experiment involving irrigation with local phreatic saline resources and application of nitrogen (N) and phosphorus (P) was conducted to alleviate spring drought and salt stresses, and solve the prominent problems of soil N and P deficiencies in the coastal severe saline-alkali soil. The experiment was consisted of two factors of saline irrigation and N and P fertilization over a four-year period in the coastal saline-alkali soil in the low plain of North China. Six treatments included no fertilizer as control (CK, WCK), only applying N (N, WN), applying both N and P (NP, WNP), each corresponding to no irrigation (the first) and irrigation with local phreatic saline water containing 8.02−9.34 g·L−1 salt (the second), respectively. The results showed that the growth and resprouting of T. chinensis occurred mainly in spring till to summer, but plant height and diameter increase and resprouting did not synchronized simultaneously. The trends of rates of plant height growing, resporuting and stem diameter thickening of T. chinensis during the growth season were as sloping shapes, triangle, and up fast following down slowly, respectively. In the first year of saline irrigation, soil water content, fresh weight of plant and leaf dry weight of T. chinensis was reduced significantly (P<0.01); but the stem dry weight was not impacted. However, after three-year saline water irrigation, the plant height and diameter growth was inhibited, the N content of stem and leaf were decreased significantly (P<0.05), but the P content of leaf increased by 11.8% on average, and branch numbers of T. chinensis increased significantly (P<0.05). The WNP treatment, i.e. saline irrigation and applying NP, retarded the decline of growth rate of plant height and stem diamter during spring to summer (May−June), not only accelerated the resprouting rate, but also increased the N and K contents of leaves, and promoted the transfer of Ca2+ and Mg2+ from stem to leaves, which resulted in a distribution change of ion in stem and leaf. WNP can alleviated the negative effect of continuous saline irrigation on the growth of T. chinensis by accelerating resprouting, promoting nutrient absorption and ion transport. The results provides a support for rational saline water irrigation and fertilization for T. chinensis in the costal serious saline-alkali soil.
Effects of nano-zero-valent iron (nZVI) on earthworm-bacteria-soil systems
LIU Chang’e, YUE Minhui, TAN Huilin, ZHANG Yue, ZHANG Weilan, XIAO Yanlan, PAN Ying, DUAN Changqun
2021, 29(10): 1722-1732.   doi: 10.13930/j.cnki.cjea.210156
Abstract(36) HTML(17) PDF(13)
Nano-zero-valent iron (nZVI) is widely used to remedy soil heavy metal pollution. However, the potential effects of nZVI on soil invertebrates, soil quality and microbial communities have not been well studied. In this study, we used Eisenia foetida (0, 10 pieces per kilogram soil) as the test species and examined the potential effects of nZVI (mass ratios of 0, 0.05%, 0.25%, and 0.50%) on the earthworm-bacteria-soil ecosystems after 15, 30, and 45 days of exposure. The results showed that after 45 days of exposure, there was no significant difference in survival rate and biomass of earthworms. The earthworm survival rate and content of malondialdehyde in the 0.50% nZVI system decreased by 27.66% and 0.86 nmol∙g−1, respectively, compared with those on day 15. However, the earthworm biomass increased by 1.20 times, and the catalase activity increased by 2.62 times. At the phylum or genus level, nZVI had no significant effects on the relative abundance, diversity index, and abundance index of soil microorganisms. Compared with the 0 nZVI system, the proportion of soil large aggregates (>250 μm), the average weight diameter of soil aggregates, and the content of available phosphorus (P) in the 0.50% nZVI system increased by 15.69%, 12.59%, and 21.20% under earthworm-mediated conditions, respectively. The proportion of soil macroaggregates and the average weight diameter of soil aggregates in the earthworm and nZVI composite systems were significantly higher than those in the corresponding single nZVI system, and earthworm activity significantly improved the stability of soil aggregates under nZVI stress (P<0.01). In this study, we found that long-term exposure to nZVI had no significant toxic effects on the community characteristics of soil microorganisms but promoted the growth of earthworms, which further improved the bioavailability of soil nutrients. This study provides a scientific basis for environmental safety assessments of nZVI in soil restoration applications.
Agricultural Ecologic Economics and Ecoagriculture
The development space of and recommendations for ecological farms in China
GAO Shangbin, SONG Chengjun, XU Zhiyu, SUN Renhua, XUE Yinghao, HU Xiaofang, QIAO Yuhui
2021, 29(10): 1733-1741.   doi: 10.13930/j.cnki.cjea.210241
Abstract(116) HTML(16) PDF(45)
Ecological farms are the main implementation objects for agricultural environmental policy in developed countries. Ecological farms represent the basic unit of promotion for ecological agriculture in China and have become an effective approach for agricultural green development. Based on a 7-year field investigation and 5 years of experience in the construction of eco-agriculture bases, the economic parameters of four regions of China (Northeast China, North China, the Middle and Lower Reaches of the Yangtze River, and South China) and three types of ecological farms (planting farm, breeding farm, plant-breeding combined farm) were obtained. According to the development plan of China’s new type of agricultural business and the proportion of 3%−5% ecological transformation, the development space of ecological farms at the regional and national scales was evaluated, and the industrial value of the ecological farms in promoting agricultural green development was analyzed. The latest requirements and policy recommendations for China’s recent ecological farm construction were put forward at the strategic level. The results show that: 1) the input-output efficiency of ecological farms in South China is the greatest and that in Northeast China is the lowest. With respect to ecological farm type, ecological farms carrying out planting-breeding have the greatest input-output ratio and average profit margin, but breeding-based ecological farms and planting-based ecological farms have lower input-output ratios and average profit margins. 2) There will be 30 000−50 000 ecological farms in China by 2022, and the scale of industrial value for the ecological farms ranks as North China > the Middle and Lower Reaches of the Yangtze River > Northeast China > South China, which will effectively drive market investment and provide employment opportunities. 3) Recently, it is necessary to build several ecological farms as the national demonstrations in the Yangtze River Delta region and other key areas, gradually promote the evaluation of ecological farms throughout the country. Meantime, optimizing the compensation policies, building a big data system, cultivating an industrialization platform, creating the investment and financing mechanism, and cultivating talented workforce and market subjects who would be engaged in the operation and management of ecological farms should be conducted.
Realization path of moderate expansion of management scale of urban leisure agriculture
LI Yufeng, LI Shanwei, XU Pu
2021, 29(10): 1742-1751.   doi: 10.13930/j.cnki.cjea.210339
Abstract(75) HTML(18) PDF(24)
It is necessary to determine how to appropriately expand the scale of leisure agriculture entities under constraints of existing resources and effectively promote sustainable development of urban leisure agriculture for realization of large-scale operational willingness of urban leisure agriculture entities limited to resources and policy restrictions of metropolises. Based on questionnaire data of 87 leisure agriculture entities in Shanghai, this study constructed a Logistic-ISM (interpretation structure model) model and took the willingness of leisure agriculture entities as measurement targets to study significant factors that affected the willingness, and logical hierarchical relationships between factors. Results showed that moderate expansion depended on the influence of the three levels of factors: 1) Among deep-seated factors, the leisure agriculture entities supported by government construction land were more willing to expand the scale of farmland. 2) Among middle-level indirect factors, the characteristics of agricultural resources, scientific park planning, innovative management capabilities, and business industrial structure positively affected the willingness of leisure agriculture entities to expand the scale of farmland, while the ecological nature of agricultural production was strong, the expansion of operators’ willingness to farmland size was weak. 3) Among the direct factors at the surface level, culturally functional leisure agriculture entities were willing to expand the scale of farmland, while leisure functional management entities tended to reduce the scale of farmland. To promote moderate scale operation of urban leisure agriculture, the government should introduce state-owned enterprises to play a demonstration effect to revitalize stock of rural land resources, and release value of resources. At the same time, leisure agriculture should provide strategic space for urban core functions, fully consider the heterogeneity of leisure agriculture entities, dig deep into rural cultural heritage, and promote transformation from undertaking the function of guaranteeing the supply of agricultural products for multiple functions to highlighting the economic, ecological, and esthetic values of agriculture and rural areas.
Influencing factors of farmers’ willingness to adopt rice-crayfish co-culture and their heterogeneity
HU Naijuan, WANG Yutao, CHEN Qian, ZHU Liqun
2021, 29(10): 1752-1761.   doi: 10.13930/j.cnki.cjea.210281
Abstract(45) HTML(9) PDF(24)
In recent years, rice-crayfish co-culture has been vigorously promoted as an ecological agricultural mode. As a direct production decision-maker, farmers’ adoption intention and its influence mechanism should be clarified for the scientific promotion and sustainable development of rice-crayfish co-culture. Based on the questionnaire survey and on-the-spot interviews data of 603 farmers in five cities of Jiangsu Province, this study explored the influencing factors and their heterogeneity of farmers’ willingness to adopt the rice-crayfish co-culture mode using the theory of planned behavior and ordered logistic model. Results show that: 1) 56.88% of the farmers in the sample were willing to adopt the rice-crayfish co-culture mode, with income expectation as the key influencing factor. 2) Behavioral attitude, subjective norm, and perceived behavioral control had significant effects on farmers’ willingness to adopt the rice-crayfish co-culture mode. The order of influence was as follows: perceptual behavior control > behavior attitude > subjective norm. 3) Under different qualifications, the factors influencing farmers’ willingness to adopt the rice-crayfish co-culture mode were heterogeneous. Specifically, complete infrastructure and part-time industrialization had a stronger influence on the willingness to adopt this mode of farmers with a high expected income. The farmers who were given subsidies and less affedcted by neighborhood had a stronger willingness to adopt the rice-crayfish co-culture mode. Farmers who were less influenced by the neighborhood had higher requirements for technical training and easeness of learning. The neighborhood effect, guidance of the agricultural technology department, difficulty of technical learning, and level of education had a significant positive effect on the willingness of farmers who participated in the technical training. Distributing subsidies and improving the guidance effect from agricultural technology departments could increase farmers’ willingness to adopt this mode in areas with incomplete infrastructure. Neighborhood effect and part-time employment had a negative impact on the difficulty of technology training, while the income expectation and environmental expectation stimulated farmers to adopt the rice-crayfish co-culture mode. Based on these results, the following policy recommendations were put forward: firstly, the government should strengthen the technical training and guidance effect; second, farmland infrastructure should be improved; third, new agricultural management subjects should be fostered quickly; and finally, differentiated incentive and guidance policies should be formulated according to farmer types.
Measurement, spatial spillover and influencing factors of agricultural carbon emissions efficiency in China
WU Haoyue, HUANG Hanjiao, HE Yu, CHEN Wenkuan
2021, 29(10): 1762-1773.   doi: 10.13930/j.cnki.cjea.210204
Abstract(107) HTML(14) PDF(49)
The efficiency of agricultural carbon emissions is a bridge between crop production and emission reduction, acting as a critical indicator of the potential for emission mitigation in agricultural production. In previous estimations, the outcomes yield the input-output efficiency of agriculture under the carbon emission constraint, rather than the efficiency of agricultural carbon emission, due to failing to separate the contribution of carbon emissions from other factors. To optimize the existing idea and understand the efficiency more precisely, a theoretical framework and a corresponding equation were developed for analysis in this study. In agricultural production, given the input factors, the efficiency of agricultural carbon emissions under the prerequisite of no desirable output was defined as the ratio of the minimum possible emissions to the actual emissons. On this basis, the GB-US-SBM model was employed to calculate the slack of emissions in 30 Chinese provinces from 2000 to 2019, reflecting the distance between the actual emission and production frontier. Then, the efficiency was estimated based on the slacks and actual emissions. Finally, the influencing factors and spillover effects of agriculural carbon emissions efficiency were explored using the spatial Durbin model. Results showed that: (1) From 2000 to 2019, the average agricultural carbon emissions efficiency was 0.778 in China, indicating considerable potential for emission reduction. At the provincial level, only Inner Mongolia and Qinghai had an efficiency of 1.000, while the rest of the provinces had different spaces for emission mitigation. (2) According to the emissions quantity and efficiency, the 30 provinces were divided into four groups. The five provinces, Henan, Hebei, Shandong, Heilongjiang, and Guangxi, belonged to a group of high emissions with high efficiency. The group of low emissions with high efficiency accounted for the majority, including 12 provinces, such as Inner Mongolia and Gansu. The group with high emissions and low efficiency covered seven provinces, such as Hunan and Hubei. Six provinces, including Zhejiang and Fujian, were classified as low emissions with low efficiency. (3) The global Moran’s index was significantly greater than 0, with a P-value under 0.01, verifying that there was a positive spatial autocorrelation in the provinces. The spatial econometric regression showed that efficiency had a significant positive spatial spillover effect, suggesting that an interactive evolution existed among close provinces. Specifically, four factors—industry structure, investment intensity, financial support for agriculture, and the degree of disaster, harmed the agricultural carbon emissions efficiency directly. By contrast, the irrigation effectiveness and urbanization indicated significant positive effects. In terms of spillover effects, the intensity of a disaster in a province negatively affected the efficiency of agricultural carbon emissions in neighboring provinces, while the urbanization rate exhibited a positive effect. Hence, it was essential to pay attention to the key factors that influence efficiency. Making full use of spillover effects could also help in achieving regional agricultural low-carbon transition. Additionally, local solutions should be addressed, owing to the regional characteristics of efficiency. This study results could provide a theoretical basis for the development of low-carbon agriculture in China.
Regional differences, dynamic evolution, and convergence of the carbon compensation rate of planting industry in China
WU Guoyong, CHEN Ying, SUN Xiaojun
2021, 29(10): 1774-1785.   doi: 10.13930/j.cnki.cjea.210225
Abstract(140) HTML(34) PDF(58)
Global warming is an increasingly serious problem. Carbon emissions from agriculture had hindered its transition to green agriculture, and carbon emissions from the planting industry cannot be ignored. Reducing the regional differences and clarifying dynamic evolution and convergence of the carbon compensation rates in the planting industry are conducive to the benign development of low-carbon agriculture. At present, few studies consider both agricultural carbon sources and carbon sinks, and an in-depth analysis of the carbon compensation rate of the planting industry is lacking. Existing studies on the agricultural carbon compensation rate focus only on the spatial effect of agricultural carbon but do not effectively analyze the sources and convergence of regional differences in the carbon compensation rate of the planting industry. Therefore, this study considered both the carbon sources and the carbon sinks and estimated the carbon compensation rate of the planting industry in 31 Chinese provinces (municipalities and autonomous districts) from 2002 to 2018. The Dagum Gini coefficient decomposition method was used to measure and decompose the regional differences, the dynamic evolution process of kernel density with non-parametric estimation was investigated, and the σ-convergence, absolute β-convergence, and conditional β-convergence models were used to test the convergence characteristics of the carbon compensation rate. The results were as follows: (1) The overall relative difference in the carbon compensation rate of the planting industry tended to expand. The relative differences in the eastern region expanded, while the relative differences in the central and western regions showed only little change. The relative differences between the eastern and western regions and the eastern and central regions increased, whereas that between the central and western regions decreased. The regional differences were the main reasons for the differences in the carbon compensation rates of the planting industry. (2) The carbon compensation rate of the planting industry in China increased annually, and the number of provinces with high carbon compensation rates increased. The provincial difference in carbon compensation rate first decreased and then increased. The carbon compensation rate in the eastern provinces increased gradually, and the inter-provincial absolute gap decreased, changing from polarization to unipolarization. The carbon compensation rate in the central provinces increased gradually, and the absolute gap decreased. The carbon compensation rate in the western provinces was relatively stable and showed little change. (3) There was no σ-convergence in the carbon compensation rate of the planting industry in the whole country and the eastern and western regions, but it was not obviously observed in the central region. The absolute and conditional β-convergences were significant in the whole country and the eastern, central, and western regions. The results of this study emphasize that regional heterogeneity in the carbon compensation rate of China’s planting industry is prominent and that the temporal trend of carbon compensation rate is generally increasing. The “catch-up effect” among provinces and the convergence trend of the carbon compensation rate growth among regions are apparent. In the future, it will be important to improve the carbon compensation rate of the planting industry to better formulate a green development strategy for regional agriculture and actively reduce regional emissions.
Temporal and spatial characteristics of China’s provincial green total factor productivity of grains from the ecological value perspective
ZHOU Yingheng, YANG Zongzhi
2021, 29(10): 1786-1799.   doi: 10.13930/j.cnki.cjea.210106
Abstract(71) HTML(3) PDF(27)
Green development is important for China’s future food safety, and measuring green productivity is an effective method to explore ways to increase green grains production. Based on the differences in the endowment of cultivated land resources in different regions, this study adopted the ecological services value evaluation method to measure the ecological value of cultivated land during the process of grain production. To incorporate the nutrient pollution and non-nutrient pollution generated in the process of grain production, the global Malmquise Luenberger index and the super efficiency model were used from the static and dynamic perspectives, to calculate China’s total factor productivity and input-output redundancy rate from 1997 to 2019. To better understand the temporal and spatial changes in China’s green total factor productivity, the spatial development characteristics of the agricultural production factors were investigated in the selected six years (1997, 2001, 2005, 2009, 2013 and 2019) using the equidistant distribution method, and Moran’s I index was used to study the spatial heterogeneity and agglomeration of green total factor productivity of grains in China. The results showed that: 1) During the study period, the ecological value of grain production reduced by 0.39%, from 647.157 billion Yuan in 1997 to 644.616 billion Yuan in 2019; a loss of 2.541 billion Yuan. The ecological value in the northeast, central, and southwest regions increased, whereas that in the east and northwest regions decreased. 2) Analysis of the environmental impact of grain production showed that the traditional total factor productivity, which does not consider environmental effects, tended to ignore the positive and negative aspects of grain production and cannot accurately assess the true efficiency of China’s grain production. After accounting for environmental factors, such as the ecological value of grain production and agricultural non-point source pollution, this study found that the green total factor productivity of grains increased by 0.60% annually, from 0.9754 in 1997 to 1.0990 in 2019, driven mainly by technological progress (1.0308). The driving effect of technical efficiency (0.9973) was weak. 3) The proportion of provinces (cities) that were relatively effective in the green total factor productivity of grains increased from 9.68% in 1997 to 67.74% in 2019. In terms of time and space, the relatively effective provinces (cities) was mainly in the eastern region and then graduallydeveloped to the northeast, central, and northwest regions. 4) Due to high pollution emissions and resource consumption, the main reasons for the provinces (cities) that were relatively ineffective in green total factor productivity of grains were the redundancy of employees in the primary industry, the use of agricultural film, and carbon emissions. 5) The green total factor productivity of grains in China had a significant positive spatial correlation dominated by high-high agglomeration, and the green total factor productivity of grains showed spatial characteristics of agglomeration in the central and southwestern high-efficiency areas. The degree of agglomeration was increasing. Based on the above results, this study advocates for a better understanding of the positive and negative effects of grain production activities, strict control of the non-grain and non-agricultural phenomenon of agricultural land, and the promotion of advanced agricultural technologies to promote the green total factor productivity of grains.
Spatio-temporal changes of water resources ecosystem services in the Hanjiang River Basin based on the shared socioeconomic pathway
CHEN Zeyi, YU Peiheng, CHEN Yiyun, JIANG Song, BAI Shaoyun, GU Shixiang
2021, 29(10): 1800-1814.   doi: 10.13930/j.cnki.cjea.210160
Abstract(48) HTML(27) PDF(12)
A comprehensive assessment framework for watershed ecosystem services and trade-offs was proposed for watershed governance and regional sustainable development in this paper. The framework integrated both shared socioeconomic pathways (SSPs) and future land use simulation (FLUS) models. The socioeconomic data of China’s provincial SSPs considering domestic development and regional differences were introduced to the FLUS model, meeting the needs of regional level land-use simulation scenarios and fully considering the interaction between human socio-economic activities and the natural environment. Taking the Hanjiang River Basin as an example, the FLUS models under different SSPs scenarios were built to evaluate the ecological and environmental effects on land-use change. We further investigated the response of water conservation and water quality purification services to social development decision-making and spatiotemporal evolution by using InVEST model. Results showed that: 1) the water production depth in 2035 under all the SSP scenarios was significantly higher than that in 2015. The increment under the SSP1 and SSP2 scenarios was relatively small, and the increment under the SSP3 scenario was relatively higher with the most intense change. The areas with increased water production depth were mainly concentrated in the southeast, central, and western regions of the Hanjiang River Basin. 2) From 2015 to 2035, due to frequent human activities and rapid urban expansion, in areas where the water production depth increased, urbanized land also increased significantly. According to the land-use simulation and water production depth change results, urbanized land had a strong water production capacity due to low vegetation coverage, weak evapotranspiration, and low permeability of hardened ground. 3) The nitrogen and phosphorus loads in the SSPs scenarios in 2035 were lower than those in 2015. The reduction under the SSP1 and SSP5 scenarios was relatively large, and the SSP3 scenario was the same as that in 2015, but the change was the most intense. The areas with increased nitrogen and phosphorus loads were mainly concentrated in the southeast and western regions. 4) According to the results of land-use simulation and nitrogen and phosphorus load change, the urbanized land had more pollutants due to the frequent human socio-economic activities, while the cropland was due to the use of chemical fertilizers and pesticides in the process of agricultural production, making part of the nitrogen and phosphorus elements not absorbed by crops. The two types of land-use caused serious pollution in the water environment of the basin. The future development planning of the Hanjiang River Basin can be based on the SSP1 scenario, referring to the economic and technological development model under the SSP5 scenario, combined with the basin functional district, optimizing the land-use structure, and ensuring the water ecological environment security of the basin while paying attention to economic development. The results of this study can be used to prepare territorial spatial planning and sustainable water resource asset management in the Hanjiang River Basin, support the construction of the Hanjiang River eco-economic belt, and promote the improvement of the water ecological environment in the Yangtze River Basin.
Intercropping enhances agroecosystem services and functioning: Current knowledge and perspectives
LI Long
2016, 24(4): 403-415.  
[Abstract](2977) [PDF 3738KB](2400)
间套作是我国传统农业的精髓, 其存在2 000多年, 必然蕴含重要的科学原理。过去的研究表明其不仅能够大幅度提高作物产量, 而且能够充分利用地上部的光热资源, 充分挖掘和利用地下部水分养分资源, 强化农田生态系统服务功能。近年来, 国内外对其资源高效利用的研究取得了显著的进步, 特别是地下部资源高效利用方面。本文首先综述了相关研究的进展: 间套作作为增加农田生态系统生物多样性的重要措施, 具有重要的生态功能, 如提高作物产量, 增加作物生产力的稳定性, 充分利用地上部光热资源和土壤水分、土壤和肥料中的氮素和磷素以及微量元素等。随后, 对间套作提高资源利用效率的机制进行了分析, 包括水分需求上的时间和空间生态位互补, 豆科/禾本科间作体系中的豆科作物生物固氮和禾本科作物对土壤氮素利用上的互补和促进作用; 磷活化能力强弱搭配的间作体系中, 磷活化能力强的作物对活化能力弱的作物的促进作用; 双子叶和单子叶植物的搭配, 改善双子叶植物的Fe、Zn等微量元素的含量等。最后, 对间套作进一步研究方向和应用提出了一些看法和思路。在研究方面, 包括作物多样性与农业可持续发展, 地下部作物种间信号的传递, 地上地下部多样性的互反馈调节机制, 以及作物生长模型等。在应用方面, 包括豆科作物纳入农业生产体系发展生态集约化农业, 利用间套作发展有机农业, 利用种间相互作用提高磷肥利用率和增加作物可食部分的微量元素含量等。并认为间套作中的机械化、育种等问题的解决将有利于间套作的进一步发展。
Agroecology transition and suitable pathway for eco-agricultural development in China
LUO Shiming
2017, 25(1): 1-7.   doi: 10.13930/j.cnki.cjea.160838
[Abstract](3853) [FullText HTML](10) [PDF 262KB](3349)
"Dual character" of rice-crayfish culture and strategies for its sustainable development
CAO Cougui, JIANG Yang, WANG Jinping, YUAN Pengli, CHEN Songwen
2017, 25(9): 1245-1253.   doi: 10.13930/j.cnki.cjea.170739
[Abstract](700) [FullText HTML](34) [PDF 1905KB](508)
Effect of plant allelochemicals on seed germination and its ecological significance
CHEN Feng, MENG Yongjie, SHUAI Haiwei, LUO Xiaofeng, ZHOU Wenguan, LIU Jianwei, YANG Wenyu, SHU Kai
2017, 25(1): 36-46.   doi: 10.13930/j.cnki.cjea.160632
[Abstract](1549) [FullText HTML](22) [PDF 1004KB](2139)
Responses of soil mineral N contents, enzyme activities and crop yield to different C/N ratio mediated by straw retention and N fertilization
LI Tao, HE Chun’e, GE Xiaoying, OUYANG Zhu
2016, 24(12): 1633-1642.   doi: 10.13930/j.cnki.cjea.160357
[Abstract](1498) [PDF 505KB](1431)
秸秆的质量, 特别是C/N是影响秸秆分解速率和养分释放的重要因素。在秸秆还田条件下, 如何科学合理地施用氮肥是秸秆利用和优化施肥研究的关键问题。本研究以秸秆还田施入碳氮的C/N为切入点, 于2012—2013年通过田间试验(设秸秆不还田不施肥、秸秆还田不施氮、秸秆还田施用无机氮肥调节C/N为10∶1、16∶1和25∶1以及秸秆还田施用有机氮肥调节C/N为25∶1处理), 研究秸秆还田不同氮输入对小麦玉米轮作田土壤无机氮、土壤微生物量氮、酶活性以及作物产量的影响。结果表明: 1)在C/N为25∶1下, 施用有机氮肥和无机氮肥对土壤无机氮含量无显著影响; 在施用无机氮肥的情况下, C/N越低土壤无机氮含量越高。2)秸秆还田施氮提高了土壤微生物量氮含量, 但是各秸秆还田施氮处理之间差异不显著; 秸秆还田不同施氮处理对脲酶活性无显著影响; 秸秆还田施氮提高了FDA水解酶活性, 并随C/N降低呈升高趋势, 施用无机氮肥的效果强于施用有机氮肥的。3)秸秆还田施用无机氮肥显著提高了小麦和玉米地上部生物量, 施用无机氮肥调节C/N为10∶1和16∶1相比于C/N为25∶1提高了小麦和玉米的苗期和成熟期地上部生物量; 施用有机氮肥调节C/N为25∶1相比秸秆还田不施氮对地上部生物量无显著影响。秸秆还田施用无机氮肥提高了作物产量, 施用无机氮肥调节C/N为16∶1产量最高, 而施用有机氮肥调节C/N为25∶1有降低作物产量的趋势。综合以上结果来看, 施用无机氮肥调节C/N为16∶1较为合理。
Nutrient release patterns and decomposition characteristics of different crop straws in drylands and paddy fields
DAI Wencai, GAO Ming, LAN Muling, HUANG Rong, WANG Jinzhu, WANG Zifang, HAN Xiaofei
2017, 25(2): 188-199.   doi: 10.13930/j.cnki.cjea.160748
[Abstract](1484) [FullText HTML](7) [PDF 495KB](1230)
以水稻、小麦、玉米秸秆和油菜、蚕豆青秆为研究对象,采用尼龙网袋法,研究了不同秸秆翻埋入旱地和水田后的腐解特性及养分释放规律,以期为紫色丘陵区农业秸秆循环利用和秸秆还田技术提供理论依据。结果表明:秸秆翻埋还田后,5种供试秸秆腐解速率均表现为前期(0~60 d)快、后期(60~360 d)慢。经过360 d的腐解,旱地秸秆累积腐解率为52.88%~75.80%,表现为油菜 > 水稻 > 玉米 > 小麦 > 蚕豆趋势,且蚕豆青秆累积腐解率显著低于其余秸秆;水田中秸秆累积腐解率为45.01%~62.12%,表现为水稻 > 玉米 > 小麦 > 油菜 > 蚕豆趋势。5种秸秆在旱地和水田中养分释放率均表现为钾 > 磷 > 氮 > 碳,在试验终点,旱地中秸秆碳、氮、磷和钾释放率分别为65.50%~87.37%、54.64%~69.72%、89.65%~98.96%和79.92%~96.63%,且油菜秸秆养分释放率高于其他4种秸秆;水田中秸秆碳、氮、磷、钾释放率变幅分别为49.95%~69.57%、32.89%~77.11%、90.70%~96.80%、77.45%~90.47%。总体表现为秸秆在旱地土壤中的累积腐解率和养分释放率均大于水田,旱地油菜和水稻秸秆较易腐解,水田水稻和玉米秸秆较易腐解释;秸秆中钾素释放速率较高。
Effect of integrated rice-crayfish farming system on soil physico-chemical properties in waterlogged paddy soils
SI Guohan, PENG Chenglin, XU Xiangyu, XU Dabing, YUAN Jiafu, LI Jinhua
2017, 25(1): 61-68.   doi: 10.13930/j.cnki.cjea.160661
[Abstract](1529) [FullText HTML](36) [PDF 337KB](996)
稻虾共作模式是一种以涝渍水田为基础,以种稻为中心,稻草还田养虾为特点的复合生态系统。本文通过10年(2005-2015年)定位试验,以中稻单作模式为对照,研究了稻虾共作模式对0~10 cm、10~20 cm、20~30 cm和30~40 cm土层土壤理化性状以及水稻产量的影响;采用投入产出法,评估了稻虾共作模式的经济效益。结果表明,长期稻虾共作模式显著降低了15~30 cm土层的土壤紧实度,其在15 cm、20 cm、25 cm和30 cm处的土壤紧实度较中稻单作模式分别降低了20.9%、29.9%、24.8%和14.7%。长期稻虾共作模式提高了0~40 cm土层中>0.25 mm水稳性团聚体数量、平均质量直径和几何平均直径,但降低了0~20 cm土层的团聚体分形维数。相对于中稻单作模式,长期稻虾共作模式显著提高了0~40 cm土层有机碳、全钾和碱解氮含量,0~30 cm土层全氮含量,0~10 cm土层全磷和速效磷含量以及20~40 cm土层速效钾含量。稻虾共作模式显著降低了0~10 cm土层还原性物质总量,但提高了20~30 cm土层土壤还原性物质总量。稻虾共作模式的水稻产量较中稻单作模式显著提高,增幅为9.5%,其总产值、利润和产投比较中稻单作模式分别增加了46 818.0元·hm-2、40 188.0元·hm-2和100.0%。可见稻虾共作模式改善了土壤结构,增加了土壤养分,提高了水稻产量以及经济效益,但增加了10 cm以下土层潜育化的风险。
Winter wheat LAI estimation using unmanned aerial vehicle RGB-imaging
GAO Lin, YANG Guijun, LI Hongjun, LI Zhenhai, FENG Haikuan, WANG Lei, DONG Jinhui, HE Peng
2016, 24(9): 1254-1264.   doi: 10.13930/j.cnki.cjea.151237
[Abstract](1841) [PDF 4566KB](1214)
叶面积指数(LAI)是评价作物长势的重要农学参数之一, 利用遥感技术准确估测作物叶面积指数(LAI)对精准农业意义重大。目前, 数码相机与无人机系统组成的高性价比遥感监测系统在农业研究中已取得一些成果, 但利用无人机数码影像开展作物LAI估测研究还少有尝试。为论证利用无人机数码影像估测冬小麦LAI的可行性, 本文以获取到的3个关键生育期(孕穗期、开花期和灌浆期)冬小麦无人机数码影像为数据源, 利用数字图像转换原理构建出10种数字图像特征参数, 并系统地分析了3个生育期内两个冬小麦品种在4种氮水平下的LAI与数字图像特征参数之间的关联性。结果表明, 在LAI随生育期发生变化的同时, 10种数字图像特征参数中R/(R+G+B)和本文提出的基于无人机数码影像红、绿、蓝通道DN值以及可见光大气阻抗植被指数(VARI)计算原理构建的数字图像特征参数UAV-based VARIRGB也有规律性变化, 说明冬小麦的施氮差异不仅对LAI有影响, 也对某些数字图像特征参数有一定影响; 在不同条件(品种、氮营养水平以及生育期)下的数字图像特征参数与LAI的相关性分析中, R/(R+G+B)和UAV-based VARIRGB与LAI显著相关。进而, 研究评价了R/(R+G+B)和UAV-based VARIRGB构建的LAI估测模型, 最终确定UAV-based VARIRGB为估测冬小麦LAI的最佳参数指标。结果表明UAV-based VARIRGB指数模型估测的LAI与实测LAI拟合性较好(R2=0.71, RMSE=0.8, P<0.01)。本研究证明将无人机数码影像应用于冬小麦LAI探测是可行的, 这也为高性价比无人机遥感系统的精准农业应用增添了新成果和经验。
Greenhouse gas exchange and comprehensive global warming potential under different wheat-maize rotation patterns
YAN Cuiping, ZHANG Yuming, HU Chunsheng, DONG Wenxu, WANG Yuying, LI Xiaoxin, QIN Shuping
2016, 24(6): 704-715.  
[Abstract](2285) [PDF 481KB](1448)
研究不同耕作措施下小麦玉米轮作农田N2O、CO2和CH4等温室气体的综合增温潜势, 有助于科学评价农业管理措施在减少温室气体排放和减缓全球变暖方面的作用, 为制定温室气体减排措施提供依据。基于2001年开始的位于华北太行山前平原中国科学院栾城农业生态系统试验站的不同耕作与秸秆还田方式定位试验, 应用静态箱/气相色谱法于2008年10月冬小麦播种时开始, 连续两个作物轮作年动态监测了秸秆整秸覆盖免耕播种(M1)、秸秆粉碎覆盖免耕(M2)、秸秆粉碎还田旋耕(X)、秸秆粉碎还田深翻耕(F)和无秸秆还田深翻耕(CK, 代表传统耕作方式)5种情况下冬小麦夏玉米轮作农田土壤N2O、CO2和CH4排放通量, 并估算其排放总量。试验期间同步记录每项农事活动机械燃油量、灌溉耗电量、施肥量, 依据燃油、耗电和单位肥料量的碳排放系数统一转换为等碳当量, 测定作物产量、地上部生物量, 估算农田碳截存量, 根据每个分支项对温室效应的作用估算了5个处理的综合增温潜势。结果表明, 华北小麦玉米轮作农田土壤是N2O和CO2的排放源, 是CH4的吸收汇, 每年M1、M2、X、F和CK农田土壤N2O排放总量依次为2.06 kg(N2O-N).hm-2、2.28 kg(N2O-N).hm-2、2.54 kg(N2O-N).hm-2、3.87 kg(N2O-N).hm-2和2.29 kg(N2O-N).hm-2, CO2排放总量依次为 6 904 kg(CO2-C).hm-2、7 351 kg(CO2-C).hm-2、8 873 kg(CO2-C).hm-2、9 065 kg(CO2-C).hm-2和7 425 kg(CO2-C).hm-2, CH4吸收量依次为2.50 kg(CH4-C).hm-2、1.77 kg(CH4-C).hm-2、1.33 kg(CH4-C).hm-2、1.38 kg(CH4-C).hm-2和1.57 kg(CH4-C).hm-2。M1和M2处理农田生态系统综合增温潜势(GWP)均为负值, 表明免耕情况下农田生态系统为大气的碳汇, 去除农事活动引起的直接或间接排放的等当量碳, 每年农田生态系统净截留碳947~1 070 kg(C).hm-2; 其他处理农田生态系统的GWP值均为正值, 表明温室气体是由系统向大气排放, CK、F和X每年向大气分别排放等当量碳3 364 kg(C).hm-2、989 kg(C).hm-2和343 kg(C).hm-2。故华北小麦玉米轮作体系中, 秸秆粉碎还田旋耕是最优化的耕作措施, 其温室效应相对较低, 而又能保证较高的经济产量。
Effect of straw strip covering on ridges on soil water content and potato yield under rain-fed semiarid conditions
HAN Fanxiang, CHANG Lei, CHAI Shouxi, YANG Changgang, CHENG Hongbo, YANG Delong, LI Hui, LI Bowen, LI Shoulei, SONG Yali, LAN Xuemei
2016, 24(7): 874-882.  
[Abstract](1473) [PDF 490KB](1003)
水分不足是限制半干旱雨养作物生长的主要因素, 地表覆盖能够改善土壤的微环境, 从而显著提高作物的产量和水分利用效率。为明确西北半干旱雨养区不同保墒措施下旱地马铃薯的土壤水分特征及其对产量的影响, 于2014—2015年设置了玉米秸秆带状覆盖种植(T1)、半膜大垄(T2)、全膜双垄(T3)和露地平作(对照, CK) 4种栽培模式, 研究了玉米秸秆带状覆盖、地膜覆盖种植对马铃薯产量、土壤水分变化及其利用效率的影响。结果表明: 不同覆盖方式能有效改善马铃薯生育期0~200 cm土层土壤水分状况, 地膜覆盖对马铃薯生育前期土壤水分保蓄效果较好, 秸秆带状覆盖对生育中后期土壤水分状况的改善效果明显。与对照(CK)相比, 3种覆盖处理均提高了土壤含水量, 其中T1处理效果最好, 较CK提高2.8%~7.8%, 尤其在伏旱阶段的块茎形成期, 0~200 cm土层土壤含水量高于地膜覆盖处理。与CK相比, T1处理马铃薯产量提高10.5%~34.2%, 水分利用效率(WUE)提高8.9%~29.8%, 达108.9~134.0 kg·hm-2 ·mm-1, 商品薯率提高14.7%~38.8%, 达82.3%~92.2%。马铃薯产量与生育期耗水量(r=0.836**)呈显著正相关。T1的产量和商品薯率均显著高于T2和T3(P<0.05)。可见, 玉米秸秆带状覆盖具有显著的纳雨保墒作用, 促进马铃薯的生长发育, 增产效果显著。其推广应用可有效提高该区降水资源的利用效率, 实现马铃薯稳产高产, 可作为西北雨养农业区旱地马铃薯生产的高效栽培新模式。
Application of spatial viewshed analysis in classifying scenic forests along the Badaling Great Wall
ZHAO Guang-Liang
2013, 21(9): 1157-1165.   doi: 10.3724/SP.J.1011.2013.01157
[Abstract](2985) [PDF 14735KB](1)
The scenic forests along the Badaling Great Wall (BGW) is 2 227.8 hm2, with a forested area of 1 314.2 hm2. The configuration and management of the scenic forests along BGW are important elements of the scenery. In this study, spatial viewshed analysis on ERDAS virtual GIS platform was used to configure the scenic forests along BGW. First, the scenic forests along BGW and a "tourist" were put in a virtual three-dimension space. The "tourist" viewed the scenic forests from 35 observation spots of different coordinates. The view ranges of the "tourist" were divided into three levels - close range (0~500 m), moderate range (500~1 000 m) and long distance (1 000~2 000 m). Then the view range and inter-visibility of the "tourist" at the three view range levels at every observation spot were recorded. Based on the view results, the scenic forests was divided into vision blunt, perceptive and sensitive areas. The results of the viewshed analysis were overlaid with vegetation and BGW forest origin data to generate a zone map. Then the landscape type of every patch of the scenic forest in the map was determined in terms of view perception. The results showed that the vision blunt area, perceptive area and sensitive area of the scenic forests along BGW were respectively 824.44 hm2, 880.4 hm2 and 3 247.77 hm2, respectively, in the farthest view rang (2 000 m). Through overlay analysis, scenic forests along BGW were divided into 119 landscape patches. For management convenience, the patches were classified into 10 forest groups. The groups included protection shrubbery in vision sensitive area, protection forest in vision sensitive area, protection shrubbery in view perceptive area, protection forest in view perception area, protection forest in vision blunt area, sightseeing forest in vision sensitive area, sightseeing forest in vision perception area, sightseeing forest in vision blunt area, recreation forest in vision sensitive area and recreation forest in vision perception area. The study provided the scientific basis for scientific management of scenic forests along BGW.
Response of suitable distribution of citrus in Sichuan Province to climate change
LIN Zhengyu, CHEN Qiang, DENG Liangji, LI Xiao, HE Peng, XIONG Ying
2019, 27(6): 845-859.   doi: 10.13930/j.cnki.cjea.180983
[Abstract](2538) [FullText HTML](65) [PDF 13495KB](65)
Citrus is one of the main fruit products of Sichuan Province, China. Due to favorable market expectations and the low occurrence of citrus diseases in Sichuan basin, there is a trend of blind expansion of citrus cultivation. However, climate change has had a significant impact on the spatial distribution of crops, and has caused the instability and vulnerability of citrus production in Sichuan. In order to optimize the citrus production space, this study established a model of the relationship between the distribution of areas suitable for growing citrus and environmental variables based on the maximum entropy model (MaxEnt), used the ROC curve to determine the model's accuracy, and used the jackknife method to screen out the dominant environmental variables. The distribution of citrus-suitable areas in Sichuan Province in 1980 and 2010 were compared using ArcGIS, revealing the changes in citrus-suitable areas over nearly 30 years of climate change. The results showed that the dominant environmental variables determining citrus suitability in Sichuan were climatic variables characterized by light, heat, and water. During these 30 years, the trend of climate warming and drying in Sichuan Province changed the structure and function of the regional ecosystem, and caused temporal and spatial variations in citrus-suitable areas. There were two broad changes in the spatial pattern of citrus-suitable areas from 1980 to 2010. First, the highly suitable areas tended to migrate to the north. The boundary of moderately suitable areas located between Chengdu Plain area and northeastern Sichuan Province moved to the southeast. Second, the suitability grade changed in a stepwise fashion. The change in the grades in marginally and moderately suitable areas was obvious. In 2010, the total highly suitable area was about 42 200 km2, moderately suitable areas covered about 41 900 km2, and the least suitable areas covered 44 000 km2; most of the province was not suitable. Using this data of the highly suitable areas, government departments can create policies to increase the quantity of citrus in the south Sichuan region and the southern Shengdu Plain. This study objectively assessed the changes in suitability for planting citrus in Sichuan Province under climate change, and provided a scientific basis for the optimization of citrus space. Application of the maximum entropy model is valuable for accurate simulation and prediction of crop distribution and can be important in guiding crop climatic suitability zoning. However, appropriate environmental variables, spatial scale, and species sampling locations should be selected for different regions and crops to reduce systematic cumulative error and improve the precision of crop climatic suitability zoning.

Editor-in-chief:LIU Changming

Competent Authorities:Chinese Academy of Sciences

Sponsored by:Institute of Genetics and Developmental Biology, Chinese Academy of Sciences; China Ecological Economics Society

Organizer:Institute of Genetics and Developmental Biology, Chinese Academy of SciencesChinese Society of Ecological Economics

ISSN 2096-6237
CN 13-1432/S
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