中国生态农业学报(中英文)

Net methane flux exchange in subtropical vegetable fields

FENG Xiaoming, WANG Kai, ZHENG Xunhua, LUO Xianbao, WANG Rui, WANG Dong

2018, 26(8): 1091-1099. doi: 10.13930/j.cnki.cjea.180187

Abstract(1299) HTML (51) PDF(1047)

Abstract:
Agricultural soil forms an important source-sink of atmospheric methane (CH₄). Studies on net CH₄ flux exchange in agricultural soil have mainly been related to rice, wheat, maize and other crops. However, field studies on vegetable fields have been seldom reported. This study was a year-round situ measurement of CH₄ flux in a typical subtropical vegetable field cultivated with cabbages using the static chamber/gas chromatography technique. The aims were to determine the characteristics of annual net exchange flux of CH₄ and the influencing factors, to estimate annual cumulative CH₄ flux, and to quantify errors in measured CH₄ flux. The CH₄ flux measurements were conducted on ridges and on inter-ridges in vegetable fields for period from January 1^st to December 8^th 2016. Environmental conditions were simultaneously observed during the measurement period. The results showed that vegetable fields constituted a weak sink of atmospheric CH₄, with annual mean flux of (-9.9±7.0) μg(C)·m^-2·h^-1 and annual cumulative flux of -0.84 kg(C)·hm^-2. High soil water content and nitrogen fertilizer application rate were probably the main reasons for the weak uptake of CH₄. The overall error in the annual cumulative CH₄ flux was -48%——16%. The main source of systematic error was in the flux calculation method used, which underestimated the flux by 32% on average. Random error was mainly produced by spatial variations of CH₄ flux, which was estimated at 16% at annual time scale. As a result, it was recommended that high numbers of spatial replications were used in conducting greenhouse gas flux measurements in agricultural soil in order to reduce random error. Another finding of the study was that CH₄ uptake measured on the ridge was significantly (P < 0.01) larger than that measured on the inter-ridge. This implied that it was better to simultaneously place chambers on areas with different field management practices; e.g. ridge and inter-ridge, row and inter-row, which efficiently avoided systematic error in measured flux.

Application and validity of BP neural networks on prediction of carbon emissions from corn production in Hexi Oasis

YAN Zhengang, LI Wei, YAN Tianhai, WANG Jun, CHEN Lei, LU Yulan, LIU Huan, TANG Jie, ZHANG Lei, CHEN Yujuan, CHANG Shenghua, HOU Fujiang

2018, 26(8): 1100-1106. doi: 10.13930/j.cnki.cjea.180084

Abstract(956) HTML (22) PDF(652)

Abstract:
Back-propagation (BP) neural network has been widely used in global climate change researches in recent years. There is also increasing research interests in the application of BP neural network on predicting carbon emission from agricultural lands. Hexi Oasis in the northern side of Qilian Mountain accounts for over 30% of total grain and over 70% of commercial grain production in Gansu Province, of which corn is the primary food crop. However, there has been little research in carbon emissions from corn fields in Hexi Oasis. Therefore, the objectives of this study were to predict carbon emissions from corn production in Hexi Oasis using BP neural network algorithm and to validate the performance of BP neural network algorithm against multiple linear regression and non-linear regression models. This study was done in Minqin Oasis (103°05'E, 38°38'N) located at the downstream of Shiyanghe River in Hexi Corridor. Data were collected on 246 local farms in a face-to-face questionnaire-driven survey. The data of production inputs were used as the inputs for the model in farm and the value of carbon emissions calculated using life-cycle assessment based on carbon emission factors published in the literatures about the similar regions and default figures reported by Inter-governmental Panel on Climate Change (IPCC). In order to predict carbon emissions based on BP neural network, the numbers of node in the hidden layer were calculated by trial and error. The results indicated that neural network structure with three layers predicted carbon emissions in corn productions in Hexi Oasis and the number of nodes for the input layer, hidden layer and output layer were 9, 10 and 1, respectively. The evaluated carbon emission was 0.763 kg(CO₂-eq)·kg^-1(DM) in the study area. To verify the validity of the BP neural network model, multiple linear regression and non-linear regression models were developed using the same dataset. The results indicated that the correlation coefficient (R²=0.984 7) of BP neural network model with the 9-10-1 structure was higher than that for the corresponding multiple linear regression and non-linear regression models. Also the root mean square error (RMSE=0.069 1) and mean absolute error (MAE=0.051 3) of BP model were lower than those of the corresponding multiple linear regression and non-linear regression models. Therefore, the performance of BP neural network model was better than that of the regression models. The BP neural network model developed in this study using data collected from the local farms in Hexi Oaiss combined the local practices and regional carbon emission factors, consequently providing a practical tool applicable in the prediction of carbon emissions in corn fields. Moreover, the validity of BP neural network model was also verified through comparison with multiple linear regression and non-linear regression models, which improved the reliability of its practical application. Therefore, the results of this study contributed new ideas and development methods to accurately predict carbon emissions in agricultural fields for the government and scientific community.

Sustainability of soil-crop systems under different long-term fertilizations in Chestnut Cinnamon soil areas

HUANG Xuefang, WANG Juanling, HUANG Mingjing, ZHAO Cong, LIU Huatao

2018, 26(8): 1107-1116. doi: 10.13930/j.cnki.cjea.180468

Abstract(833) HTML (17) PDF(591)

Abstract:
The sustainability of soil-crop systems was evaluated based on a long-term fertilization experiment to provide theoretical support for farmland fertilization and management. The long-term fertilizer experiment consisting of 8 treatments and a CK was carried out in the Chestnut Cinnamon soil of loess hilly-gully region for 26 years. The treatments included:non-fertilization (CK), 120.0 kg(N)·hm^-2 urea (N), 120.0 kg(N)·hm^-2 urea + 75 kg(P₂O₅)·hm^-2 calcium superphosphate (NP), 22 500 kg·hm^-2 organic fertilizer (M₁), M₁ + N (M₁N), M₁ + NP (M₁NP), 45 000 kg·hm^-2 organic fertilizer + 120.0 kg(N)·hm^-2 urea (M₂N) and M₂ + NP (M₂NP). A total of 19 indicators of the soil-crop system were measured, and soil nutrient index, soil microbial index, crop index and sustainability index were calculated by the triangle area method. The effects of long-term fertilization on the sustainability of soil-crop systems in the Chestnut Cinnamon soil region were discussed. The results indicated that:1) the sustainability indexes of N and M₁ treatments increased respectively by 27.1% and 141.7% compared with CK, but were 53.1% and 10.8% lower than the critical value (1.30). Although the sustainability index of NP treatment was 62.3% higher than N treatment, it was 23.8% lower than the critical value (1.30). This indicated that soil-crop systems under long-term application of single nitrogen, or low organic fertilizer or nitrogen and phosphorus were all unsustainable. 2) Nutrient index, microbial index and crop index of inorganic fertilizer (N, NP) treatments increased respectively by 7.1% and 46.4%, -6.0% and 25.4%, 40.0% and 60.0% compared with CK. Nutrient index, microbial index and crop index of single application of organic fertilizer (M₁) were respectively 98.2%, 41.8% and 31.7% higher than those of CK, showing inorganic fertilizer application improved crop index, organic fertilizer application improved nutrient index and microbial index. 3) Soil nutrient index (1.06), soil microbial index (1.04), crop index (1.00) and sustainability index (1.38) of M₁N all exceeded or equaled the critical value, which was good for the sustainability of soil-crop systems. 4) Soil nutrient indexes of M₁NP, M₂N and M₂NP increased respectively by 21.7%, 37.7% and 72.6% compared with M₁N, and the corresponding soil microbial index increased by 15.4%, 7.7% and 18.3% over M₁N. There were small differences in crop indexes of the above treatments, compared with M₁N. Sustainability indexes of the above treatments increased respectively by 28.3%, 32.6% and 68.1% compared with M₁N. The results indicated that increasing application of phosphorus or organic fertilizer over M₁N further enhanced sustainability index because of enhanced soil nutrient index and microbial index, but also increased potential environmental risk. A combination of moderate amounts of organic and inorganic N application (M₁N) was a comparatively better fertilization model, which ensured sustainable production of soil-crop systems in Chestnut Cinnamon soil region.

A discussion on land fallow rotation problems in ecologically fragile areas of the southwest karst area: A case study of Guizhou Province

LIU Yanling, LI Yu, QIN Song, HUANG Xingcheng, ZHANG Yarong, ZHANG Wen'an, JIANG Taiming

2018, 26(8): 1117-1124. doi: 10.13930/j.cnki.cjea.171151

Abstract(890) HTML (51) PDF(644)

Abstract:
The implementation of land rotation fallow has been an effective way of realizing the supply side reform of agriculture and specifically for the realization of the implementation of food crop production strategy based on farmland management and technological application. This has had a strategic impact on the development of green agriculture and guaranteeing national food security. The ecologically fragile area of the southwest karst is one of the key pilot areas of land rotation fallow system and Guizhou Province is a typical karst region. It is therefore important to analyze current conditions and develop countermeasures of land rotation fallow systems in Guizhou Province. This will give a better idea on land rotation fallow in the study area. This paper analyzed the necessity of land rotation fallow systems from two aspects-cultivated land quality and environment of Guizhou. On the basis of current conditions, the problems of land rotation fallow systems in Guizhou were put forward. Among them, the most prominent problem was the current crop rotation system in Guizhou was small without unique characteristics, and mostly passive and inappropriate. On the basis of the existing problems, countermeasures were suggested, and the implementation of land rotation fallow system, technical paths of land rotation fallow systems in different degraded/cultivated lands were discussed in detail. Highly fertile land was more suitable for developing mountain characteristic farming system, while heavy metal contaminated land should be fallowed continuously. And for areas with continuous cropping obstacle, non-point source pollution or rocky desertification, the measures of reasonable crop rotation and fallow combined with straw return, green manure use, organic fertilization, conservation tillage were suggested. Finally, the practice of land rotation fallow system in Guizhou was evaluated.

Mechanism of F-box protein family in plant resistance response to environmental stress

JIA Qi, SUN Song, SUN Tianhao, LIN Wenxiong

2018, 26(8): 1125-1136. doi: 10.13930/j.cnki.cjea.171170

Abstract(944) HTML (26) PDF(1642)

Abstract:
The UPS (ubiquitin proteasome system) mediated by SCF type E3 ubiquitin-ligase is an important mechanism to regulate biological progress at post-translation level. F-box protein, as a key component in SCF complex, could recognize its target protein for degradation. F-box gene family contains numerous members with vast diversity. In general, F-box protein contains F-box motif at N terminus and conserved domain of protein-protein interaction for recognizing target at C terminus. Due to vast diversity of conserved C terminus domains, F-box proteins could recognize wide varieties of targets. Also based on C terminal domains, F-box proteins could be divided into several subfamilies. It showed that plant F-box proteins were involved in many life processes, including response to environmental stress. Here, we reviewed current knowledge of plant F-box proteins in responding to stress. Most of the reported F-box proteins had been shown to function via SCF-dependent protein degradation, with few using SCF-independent mechanisms. Some well-understood F-box proteins were involved in phytohormone signaling pathways. Some reacted to stress through regulating the activity of transcription factors, which influenced expression of downstream genes responding to stress. Bioinformatics analyses of transcriptome showed that many predicted F-box genes were involved in stress-response reactions. Among these, only a few studies had dealt with the functions. The knowledge on the functions under environmental stress was summarized in this study. For drought, salinity and alkality stresses, F-box genes often regulated abscisic acid or ethylene signal pathways. Since drought and salt-alkaline stresses often occurred concomitantly, quite a few F-box genes had been identified to be involved in the response to both stresses in different ways. Some regulated the response to osmotic stress and ionic stress synergistically. However, some functioned inversely, suggesting that they played a role in fine regulations. For cold stress, F-box genes regulated CBF signal pathways. For biotic stress, F-box genes always regulated jasmonate and salicylic acid pathways. Meanwhile, pathogens attacked plant SCF complex for infection. Moreover, phytohormones had crosstalk to coordinate resistance in plants.

Interaction effects of mid-season hybrid rice varieties and meteorological factors on rice quality in South Sichuan winter paddy fields

XU Fuxian, ZHOU Xingbing, LIU Mao, JIANG Peng, ZHANG Lin, GUO Xiaoyi, ZHU Yongchuan, XIONG Hong

2018, 26(8): 1137-1148. doi: 10.13930/j.cnki.cjea.171123

Abstract(816) HTML (10) PDF(575)

Abstract:
In order to improve rice quality for large-scale rice production, a field experiment on mid-season hybrid rice varieties of 'ⅡY602' (high yield variety) and 'JY127' (high quality variety) was conducted in 2015-2016 under two cultivation methods[HNLD, high N and low density (pure nitrogen 210 kg·hm^-2, 90 000 points·hm^-2); LNHD:low N and high density (pure nitrogen 105 kg·hm^-2, 180 000 points·hm^-2)] in 5 sowing dates (5 March, 25 March, 20 April, 4 May, 24 May). The experiment aimed at to clarify the effects of meteorological factors at different growth stages on quality of different rice varieties under different cultivation measures. The experimental results showed that with delayed seeding time, head rice rate and length to width ratio increased; chalkiness, gel consistency decreased; and chalky grain rate in "V" type changed. There were no significant difference between two cultivation methods of high N and low density and low N and high density in all rice quality indexes and no interaction effects of rice cultivation modes, variety and seeding time. There were significant interaction effects of year, seeding time and rice variety on head rice rate, chalkiness, chalky grain rate and length-to-width ratio. Significant interaction effects were also observed between year and rice varieties in gel consistency and between seeding time and rice variety in amylose content. The descending order of influence on rice quality was:variety, climate and planting mode. Meteorological conditions required to improve rice quality included small relative humidity, high daily average temperature for the period from sowing and transplanting; low average temperature, less sunshine hours from transplanting to jointing; low daily highest temperature, high daily minimum temperature and low daily average relative humidity for the period from jointing to full-heading; and less sunshine hours for the period from full-heading to mature. The meteorological factors indirectly impacted rice quality through changing grain structure before heading in hybrid rice. High temperature after grain-filling reduced rice quality. The study provided scientific basis for high-quality rice cultivation.

Suitable sunshine and temperature for mechanical grain harvesting of summer maize in the Huang-Huai-Hai Plain

LI Shuyan, REN Liwei, LIU Tianxue, ZHANG Yibo, ZHANG Mingzhu

2018, 26(8): 1149-1158. doi: 10.13930/j.cnki.cjea.180072

Abstract(823) HTML (73) PDF(618)

Abstract:
Mechanical grain harvest is a key technology in modern maize production. Low percent of mechanical harvest is the factor limiting fully mechanized production of summer maize in the Huang-Huai-Hai Plain. Grain moisture content is the key index of mechanical grain harvest, but measurement of grain moisture content is tedious and complicated, prone to error and destruction while sampling. Grain moisture content is closely related to weather conditions. Based on the relationship among dehydration rate after physiological maturity, sunshine duration and accumulated temperature, grain moisture can indirectly be calculated. Thus building sunshine and temperature indexes for the suitability of mechanical grain reaping of different varieties can overcome the above shortcomings. It also can guide timely mechanical harvest and promote the development of mechanical grain harvest technology. In 2015 and 2016, 24 main cultivated cultivars in the Agro-meteorological Experiment Station of Chinese Meteorological Administration in Hebi City, Henan Province were investigated. Controlled pollination was used in every cultivar. Grain weight and moisture content were measured every third day after milk line reached half kernels of middle ear grains. The accumulated temperature from sowing to sampling and sunshine duration from milking stage to sampling were set as the independent variables, and grain water content in different times as dependent variables for regression analysis. And the regression equations were validated by test of significance. The sunshine and temperature indexes suitable for mechanical grain harvest of different varieties were calculated based on the threshold value of 28% grain moisture content by fitting the equations. The results showed that the order of grain moisture content in the same ear was upper part < middle part < lower part for all the tested varieties, except 'Xindan 38'. The grain moisture content in different parts of ear differed greatly in 'Xianyu 335', 'Denghai 701', 'Dedan 5' and 'Xindan 61'. The suitable accumulated temperature from sowing to harvest was 2 941-3 147℃·d and the suitable sunshine duration during milking stage to harvest stage was 179-235 h for mechanical grain harvesting of different varieties of summer maize. Sunshine duration and accumulated temperature were sorted from small to big, which showed a good consistency of variety order between temperature index and sunshine index. T-test showed that sunshine duration and accumulated temperature were significantly positively correlated with grain moisture content at harvest (P < 0.01). This indicated that sunshine and temperature indexes established in the study accurately reflected the changes in grain moisture content in each variety, and could be used to guide mechanical grain harvest. Base on sunshine and temperature indexes, 'Xindan 65', 'Xindan 68', 'Denghai 618', 'Xindan 38', 'Longping 206', 'Denghai 3', 'Xianyu 335' and 'Xindan 80' varieties needed less accumulated temperature and sunshine duration to meet mechanization standards and therefore more appropriate for mechanical grain harvest. However, 'Yuhe 998', 'Zhengdan 958', 'Denghai 662', 'Denghai 518', 'Xindan 66', 'Denghai 605', 'Dedan 5' and 'Yifeng 29' varieties had slower dehydration rates after maturity and therefore relatively less suitable for mechanical grain harvest.

Effects of herbicides on growth, development and yield of different maize varieties

XU Tianjun, LYU Tianfang, ZHAO Jiuran, WANG Ronghuan, CHEN Chuanyong, LIU Yue'e, LIU Xiuzhi, XING Jinfeng, WANG Yuandong, LIU Chunge

2018, 26(8): 1159-1169. doi: 10.13930/j.cnki.cjea.180033

Abstract(949) HTML (41) PDF(659)

Abstract:
Chemical weed control is convenient for crop field management, but the damage has become increasingly pronounced, especially for herbicides. Field experiments were conducted to study the effects of herbicides on growth process, morphological characteristics, protective enzymes activities and yield traits of different maize varieties in this study. Four widely cultivated maize varieties in the region ('Zhengdan958', 'Xianyu335', 'Jingke968' and 'Jingnongke728') and two herbicides (2, 4-D butyl ester and nicosulfuron) were used in the experiment. No herbicide (manual weeding) was set as CK treatment, the recommended application concentration (optimum concentration) of herbicides was set as T1 treatment and two-times optimum concentration was set as T2 treatment. The herbicides were applied at V4 stage of maize. The results showed that after herbicide application, the growth period of maize varieties prolonged and those of 'Zhengdan958' and 'Xianyu335' were longer than those of 'Jingke968' and 'Jingnongke728'. The growth period of tested maize varieties after applying 2, 4-D butyl ester was longer than that after applying nicosulfuron. After spraying herbicides, leaf area, root length, root surface area and root volume of the tested maize varieties decreased, while the extent of reduction increased with increasing herbicide concentration. Leaf area, root length, root surface area and root volume of 'Zhengdan958' and 'Xianyu335' were lower than those of 'Jingke968' and 'Jingnongke728'. After spraying herbicides, SOD activity, CAT activity and MDA content were significantly different among the tested maize varieties, herbicide type and herbicide dose. SOD and CAT activities of the tested maize varieties decreased, while MDA content increased. With increasing concentration of sprayed herbicides, the effect on protective enzymes activities increased. The decrease in SOD and CAT activities of 'Zhengdan958' and 'Xianyu335' was higher than those of 'Jingke968' and 'Jingnongke728'. Also with increasing concentration, the effect of 2, 4-D butyl ester treatment was higher than that of nicosulfuron. Application of herbicides after seedling resulted in a significant reduction in grain number per ear, 100-grain weight and yield. With increasing herbicide concentration, yield reduction intensified for 'Jingke968', 'Jingnongke728', 'Zhengdan958' and 'Xianyu335', decreased respectively by 8.9%, 9.3%, 14.0% and 16.5% after using 2 times concentration of 2, 4-D butyl ester. However, it decreased by 3.6%, 5.0%, 7.9% and 8.7% after using two times concentration of nicosulfuron, respectively. The reductions in yields of 'Zhengdan958' and 'Xianyu335' were higher than of 'Jingke968' and 'Jingnongke728'. Thus the application of two herbicides after seedling had significant effects on growth period, leaf area, leaf protection enzyme activity, root characteristics, yield and yield composition of maize varieties. The inhibition effect of 2, 4-D butyl on growth and development of maize was higher than that of nicosulfuron. The extent of reduction in leaf area, protective enzyme activity, root traits and yield of the tested varieties increased with increasing application concentration. The reasons for this trend were as follows:the application of herbicides controlled weeds, but also resulted in the accumulation of peroxidation products, destruction of membrane systems, decrease in leaf area, root length, surface area and volume, and acceleration of leaf senescence in the middle and late grain-filling periods of maize. Herbicide tolerance of 'Jingke968' and 'Jingnongke728' were better than that of 'Zhengdan958' and 'Xianyu335'.

Effects of rice and Canna indica L. intercropping on rice growth, disease/pest incidence and yield

LAN Ni, XIANG Huimin, ZHANG Jia'en, WANG Fugang, LUO Hao

2018, 26(8): 1170-1179. doi: 10.13930/j.cnki.cjea.171208

Abstract(841) HTML (27) PDF(669)

Abstract:
As an agricultural production pattern, intercropping not only improves biodiversity and the related ecological effects on paddy fields, but also increases agricultural production and economic benefits. This study investigated the effects of rice and Canna indica intercropping on growth, diseases and pests control, and grain yield of rice in a one-year paddy field experiment. The results showed that compared with rice monoculture, rice and C. indica intercropping decreased plant height at late tillering stage and heading stage in the early rice season. It increased leaf chlorophyll content during heading and maturity in the early rice season, and late tillering and maturity stages in the late rice season. The tiller number of rice significantly increased under intercropping by 25.20% and 11.20% at late tillering and heading stages in the early rice season and 26.01% at maturity stage in the late rice season. Besides, rice and C. indica intercropping effectively reduced the incidence of sheath blight and rice leaf folder. At medium and late tillering stages in the early rice season, rice sheath blight disease index was decreased by 35.61% and 19.55%, and also decreased significantly by 24.83% and 16.05% at late tillering and heading stages in the late rice season. At the same time, the rate of leaf-rolling by rice leaf folders were significantly decreased (by 46.35% and 60.31%) at medium and late tillering stages in the late rice season. Meanwhile, rice and C. indica intercropping improved rice yield per unit area by 11.16%. In conclusion, rice and C. indica intercropping was considered as a new eco-agriculture system which promoted rice growth, rice yield and economic benefits, and decreased the incidence of diseases and pests.

Analysis of soil bacterial diversity under cucumber-celery intercropping and its influence on cucumber Fusarium wilt

QIN Lijin, XU Feng, LIU Yongsheng, WANG Xuemin, LI Quan, YUN Xingfu

2018, 26(8): 1180-1189. doi: 10.13930/j.cnki.cjea.180097

Abstract(942) HTML (37) PDF(668)

Abstract:
Cucumber wilt is a soil disease that is highly prevalent in the production and cultivation of cucumber. The disease is highly difficult to prevent and cure. A number of studies have shown that intercropping was one of the most effective methods of reducing the occurrence of plant soil diseases. Also celery has been proven to have high allelopathy. To explore the application of allelopathic effects of celery on cucumber fusarium wilt control, we conducted cucumber and celery intercropping experiment. In the experiment, three planting patterns were set, which were cucumber-celery intercropping, celery monocropping and cucumber monocropping. The cucumber-celery intercropping pattern was regarded as treatment group and monocropping patterns of celery and cucumber regarded as the control group. The Miseq platform of Illumina Company was used to analyze 16S rDNA bacterial community diversity through high-throughput sequencing to discuss the influence of cucumber-celery intercropping on cucumber soil bacterial diversity. Cucumber was planted in soil from different planting patterns and inoculated with Fusarium oxysporium f.sp.cucumerinum (Foc) in the pot experiment to investigate the control effect of cucumber-celery intercropping on cucumber fusarium wilt. The 16S rDNA sequencing results showed that total bacterial species amount and community diversity were highest in soil under cucumber-celery intercropping, which significantly enhanced observed bacteria species index, Shannon index and Chao1 index (P < 0.05). Beta diversity clustering analysis showed there existed a difference in environmental community species between soil from cucumber-celery intercropping and mono-cropped cucumber or celery. Moreover, 15 bacterial phyla were detected. Proteobacteria, which was followed by Acidobacteria and Actinobacteria, had a distinct advantage (35.7%-38.0%). Then the proportion of bacterial species derived from cucumber-celery intercropped soil was highest (98.63%). About 428 bacterial genera were detected with 5 dominant bacterial genera, which were GP6, GP16, GP4, Gemmatimonas and Arthrobacter. Arthrobacter, Rhodoplanes, Sphingomonas and Blastococcus were dominant bacteria genera in cucumber-celery inter-cropped soil. The 4 genera demonstrated that cucumber and celery intercropping enriched the diversity of bacterial communities compared with monocropped celery or cucumber. The results of fusarium wilt inoculation experiment of cucumber suggested that the control efficiency of cucumber-celery intercropping to cucumber fusarium wilt reached 57.03%-63.54% and 66.95%-72.15% relative to monocroped celery and cucumber, respectively. Therefore cucumber-celery intercropping increased the diversity of bacterial communities, and reduced incidence rate of cucumber fusarium wilt. This was of scientific interest for the prevention and control of soil borne diseases.

Decomposition characteristics of mixed maize and soybean root residues

WANG Li, ZHOU Tao, LIU Ting, WU Yunxia, DU Yongli, LI Shuxian, GAO Yang, QIN Sisi, WEN Bingxiao, HUANG Jiale, LIU Weiguo, YANG Wenyu

2018, 26(8): 1190-1196. doi: 10.13930/j.cnki.cjea.180316

Abstract(789) HTML (28) PDF(569)

Abstract:
Maize/soybean intercropping system could potentially improve crop yield and nutrient-use efficiency. It is pivotal to elucidate nutrient efficiency of crop root residue decomposition, nutrient release and the related effects on soil biological characteristics in intercropping processes. In this laboratory incubation study, we set different combined ratios of maize and soybean root residues, including sole soybean (S), sole maize (M) root residues, S:M=3:1(SM 3:1), S:M=1:1 (SM 1:1), S:M=1:3 (SM 1:3), with soil without residues (CK) as the control. The ratio of total weight of residues to soil in each treatment was 2:98, in unit of gram (g). We dynamically measured the mineralization rate of residues, contents of total carbon and nitrogen of remained root residues and SMBC (soil microbial biomass carbon) content. The results showed that the mineralization rate of root residues was fastest during 0-9 days after incubation, which then gradually decreased after 9 days. After 60 days of incubation, the mineralization rate of root residues in all the treatments stabilized. During the whole incubation period, the cumulative release of CO₂ from maize roots was higher than that from soybean roots, but the cumulative release of CO₂ under SM 1:3 treatment was always higher than the other treatments. The cumulative release of CO₂ under SM 1:3 treatment was significantly higher than that under other treatments at the end of incubation. The content of total carbon in root residues had no significant change in the first 10 days, but decreased significantly during 10-60 days of incubation, after which it stabilized. At the end of incubation, total carbon content under SM 1:3 treatment decreased by a maximum of 24.8% from the initial value, followed by maize root residue treatment (which decreased by 21.4%), and the decrease in carbon content of the soybean root residue treatment was minimum, which was 9.7%. Total nitrogen content decreased significantly in the first 10 days of incubation, and then increased significantly until the end of incubation. Total nitrogen content of soybean root residues was highest at the end of incubation, and SM 1:3 treatment had the lowest. SMBC content first increased and then decreased during the incubation, followed by a steady change. At the end of incubation, SMBC content of SM 1:3, SM 1:1, M, S and SM 3:1 were 89.4%, 58.8%, 47.1%, 41.2% and 37.5% higher than CK, respectively. Hence, the mixtures of maize and soybean root residues had higher mineralization and nutrient release than sole maize and soybean root residues. This was beneficial to the reproduction of soil microorganisms. Among the three ratios selected in this experiment, the SM 1:3 had the best effects.

Comparison of resources use efficiencies among paddy-upland multi-crop rotation systems in the middle reaches of Yangtze River

YANG Binjuan, SUN Danping, ZHANG Yingrui, HUANG Guoqin

2018, 26(8): 1197-1205. doi: 10.13930/j.cnki.cjea.180006

Abstract(815) HTML (10) PDF(532)

Abstract:
A field experiment was conducted to search for the possibility of efficient use of farmland resources, maintain virtuous circle of agricultural ecology and optimize traditional planting patterns in the middle reaches of Yangtze River. The use efficiencies of solar radiation, heat, water and land in 5 paddy-upland multi-crop rotation systems (winter fallow-early rice-late rice → winter fallow-early rice-late rice, potato-maize soybean ‖ -late rice → vegetable-peanut corn ‖ -late rice, vegetable-peanut corn ‖ -late rice → green manure-early rice-late rice, milk vetch-early rice-late rice → rapeseed-peanut-late rice, rapeseed-peanut-late rice → potato-maize‖ soybean-late rice) with continuous cropping with winter fallow as the control were analyzed. Results showed that solar radiation use efficiency in winter, late season and for the year under paddy-upland multi-cropping rotation patterns was higher than continuous cropping with winter fallow. Annual solar radiation use efficiency was respectively 8.26%-82.50% and 2.63%-121.42% higher than continuous winter fallow during the two years. Vegetable-peanut corn ‖ -late rice → green manure-early rice-late rice pattern had the highest solar radiation use efficiency in winter, spring and in the whole year. Annual effective accumulated temperature utilization rate of paddy-upland multi-cropping rotation patterns was higher than that of continuous cropping with winter fallow, which were respectively 12.87%-21.26% and 11.17%-25.88% higher than continuous cropping with winter fallow during the two years. Vegetable-peanut corn ‖ -late rice → green manure-early rice-late rice pattern was the best among all patterns. Water use efficiency in winter, late season and for the year under paddy-upland multi-cropping rotation patterns was higher than that of continuous cropping with winter fallow, with annual water use efficiencies respectively 45.36%-83.50% and 40.00%-118.75% higher during the two years. Potato-maize soybean ‖ -late rice → vegetable-peanut corn ‖ -late rice pattern was best in late season and annual year. Vegetable-peanut corn ‖ -late rice → green manure-early rice-late rice was the highest in winter. Land use efficiency of green manure-early rice-late rice rotation pattern was the highest, with an average utilization rate of 96.11%. Land use efficiency of vegetable-peanut maize ‖ -late rice → green manure-early rice-late rice multi-cropping pattern was the highest. Comprehensive analysis showed that annual solar radiation use efficiency, annual effective accumulated temperature utilization rate, water use efficiency and land use efficiency under paddy-upland multi-cropping rotation patterns were higher than that under continuous cropping with winter fallow. Vegetable-peanut corn ‖ -late rice → green manure-early rice-late rice, and milk vetch-early rice-late rice → rapeseed-peanut-late rice performed better and thus suitable for promotion in the middle reaches of Yangtze River.

Spatio-temporal evolution and potential analysis of cropping index in Sichuan Province during 2000-2016

TIAN Luo, ZHOU Wenzuo, HE Wanhua, ZHAO Xiao, LIU Donghong, ZHANG Jincheng

2018, 26(8): 1206-1216. doi: 10.13930/j.cnki.cjea.171086

Abstract(962) HTML (15) PDF(1165)

Abstract:
Cropping index is one of the basic indexes used to measure use intensity, space-time distribution and changes of farmlands at regional scale, which is essential for basis agricultural decision-making. To investigate cropping indexes, the related changes and potential cropping indexes of farmlands in Sichuan Province, a long-term (2000-2016) series of MODIS-NDVI remote sensing data products were used to reconstruct NDVI time-series curve using Asymmetric Gauss Fitting Function (AGFF). The peak frequencies of the NDVI time-series curves were used for determining the spatial distributions and temporal changes of annual cropping indexes by using the second order difference method. Then the spatial pattern of potential and promotable potential cropping indexes of farmland in Sichuan Province were simulated using the temperature-rainfall model, meteorological data and land-use maps to refine farmland dynamics in the region. The aim of the study was to provide scientifically-drive recommendations to local governments on the regulation of intensive development of farmlands in the study area. The results showed that single cropping pattern, which made up 78.05% of cultivated land, was the main cropping system in Sichuan Province for the period 2000-2016. This mainly distributed in the Northwest Sichuan Plateau region, Northeast Sichuan, Southwest Sichuan Hilly area and Panxi Valley region. The double cropping system mainly distributed in Chengdu region and the surroundings. Overall, the spatial distribution of cropping index (MCI) in Sichuan Province decreased in trend from Chengdu and the surroundings to other regions. According to the promotable and potential cropping indexes, Sichuan Province had 89.7% of cultivated land with higher promotable potential in multiple cropping. Chengdu and the surroundings had lower promotable potential cropping index (PMCI_p < 50%) and higher inter-annual fluctuation (standard deviation of cropping index > 60%) than other regions in Sichuan Province. Cultivated land in the northeastern and southern areas of Sichuan (which accounted for 65.6% of the total area of Sichuan), was higher in promotable potential cropping index (PMCI_p ≥ 50%) and less inter-annual fluctuation compared with Chengdu and the surroundings. There was the likelihood for this to become the best suitable land with the highest cropping index in Sichuan Province. Accounting for 10.3% of cultivated land area of Sichuan in the northwest and northeast mountainous areas (with negative promotable cropping index) formed the main region of agricultural over-development in the study area. There was therefore the need to classify these farmlands into ecological restoration areas. The cropping indexes extracted by integrating the phenology of crops and long-term series of remote sensing data were significantly correlated with the statistics values in Sichuan, indicating the method was applicable in evaluation of cropping index in provincial scale. The result was beneficial reference to policy decision of regional planting structure.

Evaluation of ecological risk and carbon fixation from land use change: A case study of Huanghua City, Hebei ProvinceE

LIU Jianhua, XU Hao, WANG Yao, LI Hang, SHEN Wendong

2018, 26(8): 1217-1226. doi: 10.13930/j.cnki.cjea.170991

Abstract(873) HTML (23) PDF(554)

Abstract:
The rapid development of social economy has had a profound impact on the change of land use pattern. Ecological risk assessment had played an important role in controlling ecological risk and realizing sustainable development. Changes in land use pattern will exert an effect on regional ecological risk and carbon sequestration. Combined evaluation of ecological service value and ecological risk assessment has become the new mode of studying ecological problems. This paper used Huanghua City in Hebei Province, China as a case study and remote sensing images for 1995, 2005 and 2015 as the basic data to analyze this pattern change. While ecological risk index was constructed based on the pattern of change in land use, InVEST was used to analyze the change in carbon storage. Finally, we analyzed the correlation between changes in ecological risk and carbon stock. The purpose of the study was to determine rational utilization of land resources for healthy development of ecological environment. The results showed that:1) cultivated land, saline land and construction land were the main land use patterns in Huanghua during 1995-2015. Compared 2015 with 1995, the degrees of fragmentation and separation in cultivated land, grassland and construction land increased, while the separation and fragmentation of garden plot and saline land decreased. While the loss index of garden plot and the saline land reduced, that of other land use types increased. 2) Total ecological risks of Huanghua City in 1995, 2005 and 2015 were 12.58, 10.32 and 11.10, respectively. During the study period, low risk and high risk area constituted the main risk areas. The area of the low risk gradually increased and was concentrated in the south. Then the area of high risk gradually decreased and was concentrated in the central and eastern coastal zones. 3) According to InVEST simulation results, the carbon storage in Huanghua City increased and then decreased eventually. In 1995, 2005 and 2015, total carbon storages in Huanghua were 23.870 5 million tons, 24.915 1 million tons and 20.288 6 million tons, with respective carbon densities of 107.63 t·hm^-2, 112.34 t·hm^-2 and 93.16 t·hm^-2. Change in carbon storage under each land use pattern was more consistent with change in the corresponding land area. 4) Correlation between changes in ecological risk and carbon stock was significant. The determinants of the correlation between changes in ecological risk and carbon stock in 1995-2005 and 2005-2015 were 0.69 and 0.72 (P < 0.01), showing a significant negative correlation. It suggested that ecological risk assessment and ecosystem services valuation were concurrently assessable. This was one of the innovative points of the research. The assessment of ecological risk and carbon storage in Huanghua using change in land use pattern was important for the realization of sustainable utilization of land resources and improvements in regional ecological environment.

Dynamic changes in arable land requirements for food consumption in China

LIU Chunxia, WANG Fang

2018, 26(8): 1227-1235. doi: 10.13930/j.cnki.cjea.171047

Abstract(785) HTML (4) PDF(763)

Abstract:
With the development of China's social economy and improvement of living standard of the people, food consumption level and structure in the country have changed greatly. The ability to guarantee land resources, closely related with food consumption, has also attracted more attention in international community. Vast amounts of arable lands are needed to produce food, but land resources suitable for production of crops in China are very limited. Therefore, in order to evaluate food consumption and its impact on the demand of agricultural land resources in China, we first assessed the dynamic changes in arable land requirements for food consumption in China for the 1961-2013. Then we quantitatively examined the contributions of population growth, dietary change and technological change to land requirements for food (LRF) based on the LMDI decomposition model. The results indicated that dietary pattern of Chinese residents changed apparently to nutrient-rich from 1961 to 2013, people gradually consumed more animal food and vegetable oil other than traditional plant-based food. This induced obvious increment in LRF, which was 1.05×10⁸ hm²·a^-1 in 1961, 1.75×10⁸ hm²·a^-1 in 2013. China increasingly depended on imports to meet LRF according to the analysis of domestic production and import of food. Remarkably, this path of dependence risked the vulnerability to volatile global food prices. LMDI decomposition results revealed that population and dietary pattern were equal in contribution to LRF increase, while scientific and technological advancement contributed relatively less to decrease in LRF, which were not enough to make up for the increases in population and dietary change. And dietary change rather than the rapid growth of population had become the most critical variable determinant of LRF in China for the foreseeable future. Additionally, we found that the development in underlying factors of LRF was not often linear. Caution also seemed warranted in considerations of future LRF in China based on sequential trend assumptions. In summary, the LRF increased gradually from 1961 to 2013, and dietary pattern of China's residents was the key factor affecting LRF.

Spatio-temporal distribution characteristics of drought in Shandong Province and it relationship with ENSO

XU Zehua, HAN Mei

2018, 26(8): 1236-1248. doi: 10.13930/j.cnki.cjea.171024

Abstract(1040) HTML (39) PDF(1430)

Abstract:
Drought is the most devastating natural disaster in the world. In recent years, prolonged droughts with huge impacts had caused enormous economic losses in China. Shandong Province belongs to a semi-humid climate, with complex and diverse underlying surfaces and sparse surface vegetation that is sensitive to climate change. Due to uneven distribution of precipitation during the year, drought and flood disasters in Shandong Province have been frequent, with significant impact on agricultural production and socio-economic development. Given the above, it was pivotal to study the spatial and temporal changes in drought in Shandong Province for application in drought monitoring and water resources management. Based on monthly precipitation and average temperature data from 15 meteorological stations in Shandong Province from 1964-2010, the frequency of drought at different time-scales in Shandong Province was quantitatively analyzed using standardized precipitation evapotranspiration index (SPEI). Using the Mann-Kendall non-parametric test method and Arcgis platform, the trends in temporal and spatial variation of drought in Shandong Province in the recent 50 years were analyzed. In order to study the impact of El Niño/Southern Oscillation (ENSO) on drought in Shandong Province, the continuous wavelet (CWT), cross wavelet transform (XWT) and wavelet coherence spectrum (WTC) were used to analyze the correlation between SPEI and ENSO index with the periodic characteristics. The results showed that SPEI at multiple time-scales reflected drought condition in Shandong Province. The sensitivity of time-varying SPEI was obviously different. The smaller the time-scale was, the greater the variation range was. In the recent 50 years, Shandong Province had an obvious warming trend, which was most significant in the eastern part of the province. Decrease in precipitation and increase in temperature induced warm and dry climate in Shandong, which aggravated drought conditions in the province. The spatial distributions of SPEI and annual precipitation in Shandong Province were consistent with the trend in spatial change, and the trend in the west had become more humid and in the east more dry. On the time scale of drought occurrence, the frequency of monthly drought was higher than that of annually drought, with spring and autumn having the most severe droughts across the four seasons. The highest frequency of drought occurred in West Shandong and Northwest Shandong Plain, with distinctive difference among different regions. With ENSO warm events, Shandong became prone to drought and ENSO cold events reduced droughts conditions. The annual-inter-annual oscillation cycle characteristics of SPEI was 1.0-2.5 years, showing similarity with the characteristics of Multiple ENSO Index (MEI). In high energy sector, the resonance period was 5.0-6.0 years for SPEI and MEI, but 1-2 months ahead of MEI. In low energy sector, there was a negative phase resonance period for SPEI and MEI of 3.0-3.8 years. The study provided a quantitative basis for understanding the spatial and temporal changes in drought in Shandong Province under global climate change. It also was helpful to decision-makers by improving preparedness and adoption of appropriate policies for agricultural management.

Effect of potassium fertilizers on immobilization remediation of Cd-polluted soils using sepiolite

HUANG Rong, XU Yingming, HUANG Qingqing, SUN Guohong, YIN Xiuling, LIANG Xuefeng, QIN Xu

2018, 26(8): 1249-1256. doi: 10.13930/j.cnki.cjea.171138

Abstract(902) HTML (15) PDF(561)

Abstract:
Cadmium (Cd) is one of the most toxic pollutants in soil environments because of its persistence, toxicity and potential for bioaccumulation. Natural sepiolite has recently been found as a cost-effective material for immobilization remediation of metal-contaminated soils due to its low cost, high cation exchange capacity, and high specific surface area associated with the small particle sizes. In agricultural production, the application of various fertilizers is vital, but the effects of fertilizer addition to polluted soils on immobilization remediation have been little investigated. In previous studies on immobilization experiments, only remediation effects were emphasized. The effects of nutrient elements on remediation process promotion or inhibition has been largely ignored. For large application of immobilization remediation in different areas with various fertilizer forms, the impact of fertilizers on the process must be determined. In this research, natural sepiolite (10 g·kg^-1) was used as immobilization agent and meanwhile potassium chloride (KCl) and potassium sulphate (K₂SO₄) used as representative potassic fertilizers in rape pot experiments to determine the effects of potassic fertilizers on the process of immobilization remediation of Cd-polluted soil. The potassium fertilizer content was calculated as K₂O, with 0.1 g·kg^-1, 0.2 g·kg^-1 and 0.3 g·kg^-1, respectively. The results showed that rape biomass significantly increased (by 6.06%-10.05%) after the application of K₂SO₄, compared with sole sepiolite treatment. Cd contents in shoot increased respectively by 16.38%-60.73% and 15.62%-25.19% after the application of KCl and K₂SO₄. KCl and K₂SO₄ had little effects on soil pH, but increased exchangeable Cd concentration significantly (respectively by 25.51%-34.65% and 18.5%-24.96%). Sepiolite conduced Zeta potential of soil samples to shift in negative direction, while the addition of KCl and K₂SO₄ made the Zeta potential of soil samples increase. The maximum adsorption of Cd by sepiolite in aqueous solution was 5.30 mg·g^-1, but KCl and K₂SO₄ reduced sorption of Cd on sepiolite, with maximum sorption of respectively 2.87 mg·g^-1 and 4.92 mg·g^-1. Bioavailable fractions of K, Mn, Cu and Zn were enhanced significantly by the additions of KCl and K₂SO₄. Considering the various factors during passivation of sepiolite to Cd-contaminated soils therefore, the effect of application of K₂SO₄ on passivation was less than that of application of KCl. On the whole, K₂SO₄, rather than KCl, was recommended potassic fertilizer for remediation of Cd-contaminated soils using sepiolite.

2018 Vol. 26, No. 8