中国生态农业学报(中英文)

Extension potential of rice-fish co-culture system: A case study of 10 provinces in South China

HU Liangliang, ZHAO Lufeng, TANG Jianjun, GUO Liang, DING Lilian, ZHANG Jian, REN Weizheng, CHEN Xin

2019, 27(7): 981-993. doi: 10.13930/j.cnki.cjea.190203

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Abstract:
Rice fields can provide habitats for a wide range of aquatic animals, including carps, crabs, crayfish, soft shell turtles, which makes it possible to couple rice culture with fish production. This is referred to as the rice-fish co-culture system. The suitability of rice fields in a specific region for the rice-fish co-culture system often depends on local natural and social economic conditions. An understanding of the potential of rice fields for use in the rice-fish co-culture system would aid effective extension of rice-fish co-culture system and maximize the benefits of this extension. In this study, we assessed the effects of natural and social-economic conditions on the extension of the rice-fish co-culture system in 10 provinces of South China, and predicted the potential of fish yield from rice fields in the rice-fish co-culture system extension. We first built a geographical distribution database of all rice fields in the study area by using a geographic information system (GIS) comprising meteorological data and national statistics. We then assessed the extension priority of different rice fields with a hierarchy model of all assessment criteria and the weighted linear combination method. To assess the extension benefits, we further established a simple model that included rice field area, extension rate, and fish yield. The results showed that rice fields in our study region could be divided into four classes of extension priority based on natural and social-economic scores. The area proportions of four classes were:29.6% for class 1 (3.59×10⁶ hm²), 16.9% for class 2 (2.05×10⁶ hm²), 24.2% for class 3 (2.94×10⁶ hm²), and 29.4% for class 4 (3.57×10⁶ hm²). However, the proportions of rice fields in the four classes were different in the ten provinces. For the provinces of Hunan, Sichuan, Jiangxi, and Zhejiang, half of rice fields were grouped into class 1 and 2, whereas all the rice fields of the provinces of Yunnan and Guizhou were grouped into class 3 and 4. The rice fields of class 1 and class 2 were suitable for the extension of the intensive rice-fish co-culture system, and able to produce a maximum yield of 3.77×10⁶ t and 2.15×10⁶ t of fish in a growing season, respectively. The rice fields of class 3 were suitable for extension of the extensive or intensive rice-fish co-culture systems, and able to produce a maximum yield of 0.62×10⁶ t or 3.09×10⁶ t of fish in a growing season, respectively. The rice fields of class 4 were not suitable for rice-fish co-culture system. Our results may provide an important basis for extending the rice-fish co-culture system in South China. The results may also be a reference for rice-fish co-culture system development in other rice culture areas.

Assessment of the direct radiation effect of atmospheric aerosol on maize yield in China by using APSIM model

KONG Xiangna, ZHAO Junfang, XU Hui, XU Jingwen

2019, 27(7): 994-1003. doi: 10.13930/j.cnki.cjea.181071

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Abstract:
Owing to the increasingly serious atmospheric aerosol pollution, the impact of aerosols on the growth and development of crops can no longer be ignored. In this paper, the Beijing, Xianghe, and Taihu stations in China with perennial observation data in global aerosol monitoring network (AErosol RObotic NETwork, AERONET) were used as the research stations. Based on the AERONET data, MODIS surface albedo data and the 6S (Second Simulation of a Satellite Signal in the Solar Spectrum) radiation transfer model, the effects of aerosol direct radiation at three research stations from 2001 to 2014 were calculated. Then, the applicability of the APSIM (Agricultural Production Systems Simulator) model was evaluated, and the impacts of direct aerosol radiation on maize yield in China were analyzed by using the APSIM model. The results showed that:1) the verified APSIM maize model had good applicability in the maize producing areas of Beijing, Xianghe, and Taihu in China. The results of APSIM model were a better simulation of the developmental stages and the yield of maize, in which normalized root mean square error (NRMSE), coincidence indicator (D), and determinate coefficient (R²) were 1.55%-6.24%, 0.80-0.99, and 0.75-1.00, respectively. 2) Aerosols reduced direct solar radiation, and the decreasing trend was mainly affected by the net radiation flux of aerosols. The total solar radiation of Beijing, Xianghe, and Taihu stations reduced by 31.95%, 14.74% and 28.30%, respectively, from 2001 to 2014. 3) The direct radiation effect of aerosols caused a reduction in maize yield. The maize yields of the Beijing, Xianghe, and Taihu stations, caused by the direct radiation effect of aerosols, were reduced by 28.44%, 14.89%, and 13.43%, respectively, from 2001 to 2014. In general, because of the direct radiation effects of atmospheric aerosols, the maize yields from 2001 to 2014 were reduced by 13.43%-28.44% in three highly polluted areas (Beijing, Xianghe, and Taihu) in China.

Effects of biochar and straw on greenhouse gas fluxes of corn fields in arid regions

CHENG Gong, LIU Tingxi, LI Dongfang, DUAN Limin, WANG Guanli

2019, 27(7): 1004-1014. doi: 10.13930/j.cnki.cjea.190008

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Abstract:
Biochar refers to a kind of stable and carbon-rich solid matter, generally composed of biomass and fertilizers, such as litter and crop straw, which have been pyrolyzed and carbonized under high temperatures in either a completely anaerobic or partially anoxic state. To explore the effects of biochar and straw returning on the greenhouse gas fluxes of corn fields in arid areas, an experiment was conducted on a corn field in the Horqin District, Inner Mongolia. A static chamber-gas chromatography (GC) technique was used to conduct in situ observations on greenhouse gas (CO₂, CH₄, and N₂O) fluxes under different experimental treatments. These treatments included different application rates of biochar:0 (CK), 15 (C15), 30 (C30), and 45 t·hm^-2 (C45); and straw returning (SNPK). For the experiments, the global warming potential (GWP) and greenhouse gas intensity (GHGI) during the growing season were estimated. The results showed that the addition of biochar could significantly reduce the soil CO₂ and N₂O emissions. During the growing season, the CO₂ fluxes in the C15, C30, C45, and SNPK treatments decreased by 21.16%, 14.34%, 17.02%, and 19.93%, respectively. Among these treatments, C15 exhibited the best emission reduction effect. Compared with CK, the N₂O fluxes of C15, C30, C45, and SNPK reduced by 24.42%, 56.83%, 86.25%, and 28.28%, respectively. With the increase in biochar rates, the inhibition effect on N₂O emissions increased. Among the treatments, C45 provided the greatest reduction in emissions. Appropriate addition of biochar could promote the soil to absorb CH₄. Compared with CK, the soil CH₄ absorption of C15, C30, and SNPK increased by 56.62%, 32.05%, and 40.35%, respectively. The CH₄ absorption of C45 decreased by 81.36% compared with CK. Excessive biochar could cause less CH₄ absorption in the soil. There was a positive correlation between soil CO₂ flux, temperature, and moisture during the growing season. The CH₄ and N₂O fluxes of CK, C15, and SNPK were significantly correlated with the soil temperature and moisture during the growing season. However, the CH₄ and N₂O fluxes of C30 and C45 did not exhibit a significant correlation with the soil temperature or moisture during the growing season. The addition of biochar and straw returning to the field had a significant effect on increasing the corn yield and reducing the GWP and GHGI in the farmlands. Biochar and straw returning both effectively increased the corn yield in the Horqin District. The corn yield increased as the amount of biochar increased. From the perspective of the GWP, a biochar rate of 15 t·hm^-2 had the best overall effect on reducing greenhouse gas emissions, similar to the SNPK treatment. From the perspective of the GHGI, biochar and straw returning had certain economic benefits and significant reducing-effects of greenhouse gas emissions. Among the different treatments investigated, 15 t·hm^-2 of biochar had the highest comprehensive benefits, and the C45 and SNPK treatments were slightly inferior to C15, but higher than C30. Therefore, from the perspectives of comprehensive economic benefits and environmental factors, it was suggested that 15 t·hm^-2 of biochar should be added to the farmlands in Horqin when growing corn. If biochar was not available, straw returning can also be considered to achieve an increase in corn yields and decrease in greenhouse gas emissions.

Inhibitory effect of biochar-enriched biocontrol agents on Phytophthora capsici

WANG Guangfei, MA Yan, GUO Dejie, LUO Jia, LIANG Yonghong, QIU Meihua

2019, 27(7): 1015-1023. doi: 10.13930/j.cnki.cjea.190009

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Biochar is known to effectively control the Phytophthora blight of pepper. To further understand the mechanisms of biochar-mediated disease control, we screened the biochar-enriched beneficial microorganisms and evaluated their antagonistic activities against Phytophthora capsici. A pot experiment was conducted to determine the effects of straw biochar on the control of Phytophthora blight. Both qPCR and dilution-plate methods were used to identify the biochar-enriched biocontrol microorganisms in rhizosphere soils. Potential antagonistic strains, which were biochar-enriched, were screened using the selective isolation method and rhizosphere colonization assay, after which their antagonistic activity against P. capsici in soil was determined. The results showed that biochar amendment could significantly reduce the abundance of P. capsici and severity of the Phytophthora blight of pepper by 95.1% and 91.1%, respectively. In addition, biochar amendment significantly increased the abundances of Trichoderma, Penicillium, Aspergillus, Bacillus, Pseudomonas, and Sphingomonas by 2.22, 4.09, 3.89, 2.45, 1.45, and 1.30 times, respectively. Twenty-two potential biocontrol strains that can be enriched by biochar were screened from biochar-amended rhizosphere soils using the selective isolation method. Comparing the colonization between the biochar-amended and control rhizosphere soils, two strains of Trichoderma, three strains of Penicillium, two strains of Aspergillus, three strains of Bacillus, three strains of Pseudomonas, three strains of Streptomyces, and two strains of Sphingomonas were confirmed to be enriched by biochar. Trichoderma (TR1 and TR3), Penicillium (PE1), Aspergillus (AS1 and AS2), Bacillus (BA1, BA2, and BA3), Pseudomonas (PS1 and PS3), and Streptomyces (ST1, ST4, and ST5) strains could significantly reduce the abundance of P. capsici in the soil. Among these antagonistic stains, Trichoderma (TR1 and TR3), Aspergillus (AS1 and AS2), Bacillus (BA1 and BA2), Pseudomonas (PS1 and PS3), and Streptomyces (ST1) strains in synergism with biochar facilitated a significant increase in the inhibition of P. capsici. Thus, Trichoderma, Aspergillus, Bacillus, Pseudomonas, and Streptomyces enriched by biochar might play an import role in the suppression of Phytophthora blight of pepper under biochar amendment.

Experimental study on soil water threshold of luxury transpiration in winter wheat leaves during flowering and filling stage

WANG Yakai, DONG Baodi, QIAO Yunzhou, YANG Hong, JIN Lele, LIU Jinyue, LIU Mengyu

2019, 27(7): 1024-1032. doi: 10.13930/j.cnki.cjea.190093

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Abstract:
Luxury transpiration water consumption has a lower contribution to the formation of photosynthetic products and crop yield, and the flowering and filling stage is the key period for the yield of winter wheat. In order to efficiently and accurately regulate the transpiration of crops, to determine the soil moisture threshold affecting luxury transpiration is important. In this study, the winter wheat variety 'Shixin 828' was used as study material. Pot experiments were carried out in an artificial climate growth box. The effects of soil moisture on stomatal conductance, photosynthetic rate and transpiration rate of crops were quantitatively studied in order to define soil moisture threshold for luxury transpiration at flowering and filling stage. The results showed that the stomatal conductance was closely related to soil water suction. When soil water suction was low, stomatal conductance decreased rapidly with the increase in soil water suction. When soil water suction was high, stomatal conductance decreased slowly. When water suction was less than 1.2 MPa, the photosynthetic rate was close to the maximum value. Then as water suction increased, the photosynthetic rate decreased gradually in the form of a parabola. The transpiration rate decreased linearly with a reduction rate of 2.3 mmol·m^-2·s^-1·MPa^-1 as soil water suction increased. The coupling relationship between photosynthesis and transpiration was described by the Michaelis-Menten equation. When the transpiration rate was lower than K_Tr=2.179 mmol·m^-2·s^-1, the photosynthetic rate increased linearly with the transpiration rate; but when the transpiration rate was higher than K_Tr, the increase in net photosynthetic rate became slower, and luxury transpiration occurred. When soil water suction corresponded to the luxury transpiration threshold of K_Tr (1.76 MPa), the leaf photosynthetic rate was at a high level (about 16 μmol·m^-2·s^-1), and the leaf water use efficiency (WUE_L) was at the highest level[7.3 μmol (CO₂)·mmol^-1(H₂O)]. In summary, the luxury transpiration of wheat leaf started with a shift from the highest WUE_L to lower while photosynthetic rate maintaining a rather higher level. Based on the Michaelis-Menten equation, the relationship between photosynthesis and transpiration, and the linear relationship between transpiration and soil water suction, soil water suction of 1.76 MPa was found to be the soil water threshold for the start point of luxury transpiration of wheat leaves during the flowering and filling stage.

Effect of water and nitrogen on the yield and quality of forage rape grown after wheat in South Xinjiang

ZHU Qianqian, LIU Guohong, XU Yongmei, YANG Jinyu, ZHANG Yanhong

2019, 27(7): 1033-1041. doi: 10.13930/j.cnki.cjea.180997

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Abstract:
A field randomized block experiment was conducted to investigate the effects of water and nitrogen on the yield and quality of multiple cropped forage rape after wheat harvest, by analyzing the variation characteristics of rapeseed yield and its four typical feed quality indicators under different water and nitrogen treatments through fuzzy similarity priority ratio method. The experiment included two factors:irrigation quota and nitrogen application rate; irrigation quota was 3 000 m³·hm^-2 (low water), 4 500 m³·hm^-2 (middle water), and 6 000 m³·hm^-2 (high water) (W1, W2, W3); nitrogen application rates were 140.6 kg(N)·hm^-2 (low nitrogen), 187.5 kg(N)·hm^-2 (medium nitrogen), and 234.4 kg(N)·hm^-2 (high nitrogen) (F1, F2, F3). The results showed that the suitable irrigation and nitrogen levels had significant interaction advantages on fresh weight, dry weight, yield, and quality of forage rape, while an excess or deficiency in irrigation and nitrogen levels reduced mutual advantage. The fresh weight, dry weight, and yield of forage rape under the same irrigation quota improved with the increase in nitrogen application rate. Under the same nitrogen application rate, the fresh weight, dry weight, and yield of forage rape increased with the increase in irrigation quota. Improving irrigation quota was better than increasing the nitrogen application rate. Yield under high water + medium nitrogen treatment increased by 86.90% when compared with yield under low water + low nitrogen treatment. Nitrogen application rate and irrigation-nitrogen application interaction significantly affected the quality of forage rape; in W2F2 treatment, crude protein content increased by 36.91% when compared with W3F3 treatment. The neutral-detergent fiber under W2F1 treatment was the lowest, at 32.66%, significantly lower than that under W3F3 treatment. The acid-detergent fiber under W3F1 treatment was the lowest (24.74%), which was lower than that under W3F3 treatment by 16.49%. The crude fat content was the highest under W3F3 treatment, at 1.45%. Comprehensive consideration of yield and quality revealed that the suitable water and nitrogen application measures for cultivating forage rape in South Xinjiang was high water and high nitrogen[6 000 m³·hm^-2, 187.5 kg(N)·hm^-2].

Influence of optimized nitrogen management on the quality of medium hybrid rice under different ecological conditions

LI Shuxian, PU Shilin, DENG Fei, WANG Li, HU Hui, LIAO Shuang, LI Wu, REN Wanjun

2019, 27(7): 1042-1052. doi: 10.13930/j.cnki.cjea.181087

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Abstract:
The effects of different nitrogen (N) treatments on rice quality were studied at two different ecological sites (Wenjiang and Shehong), using single-factor experiment with a randomized block design and 'F You 498' as the test material. The results showed that the milling quality, appearance, and grain crude protein content were better in the Wenjiang rice. In the Shehong rice, the peak viscosity and breakdown viscosity were higher and the setback viscosity was lower; the cooking and eating qualities were better and the amylose content was higher. With N fertilizer applied, the rice milling quality and amylose and grain crude protein contents were significantly increased, and the breakdown viscosity was significantly decreased. At the same time, N fertilization increased the peak viscosity and reduced the setback viscosity of Shehong rice, whereas it improved the appearance, decreased the peak viscosity, and increased the reduction value of Wenjiang rice. Compared with the fertilization practices of farmers, the optimal N fertilizer treatments (ONM1:optimized N management; ONM-_N1:optimized N management with 15% N reduction; and ONM+_N1:optimized N management with 15% N increase) and optimized N management of polyaspartic acid-urea (PASP-urea) treatment increased the amylose and grain crude protein contents. Optimal N fertilizer treatment reduced the chalky rice rate and chalkiness ratio, and improved the appearance of Wenjiang rice. At both ecological sites, the optimal N fertilizer treatment reduced the peak viscosity and breakdown viscosity, increased the setback viscosity, and worsened the cooking and eating qualities of the rice. At the same time, it increased the milled rice rate of Shehong rice and the head rice rate of Wenjiang rice. In comparison with the ONM1 treatment, PASP-urea treatment reduced the milled rice ratios and head rice rates of the two types of rice and the chalky rice rate of Wenjiang rice, whereas it increased the chalky rice rate and chalkiness ratio of Shehong rice, worsening its appearance. At the same time, PASP-urea applied at the basal stage only and spilt-applied at the basal stage and at panicle initiation reduced the amylose and grain crude protein contents. Optimized N management of PASP-urea treatment reduced the peak viscosity and breakdown viscosity of the two rice types and the amylose content of Wenjiang rice, whereas it increased the grain crude protein contents of the two rice types and the amylase content of Shehong rice. Compared with the OMN1 treatment, the ONM-_N1 and ONM+_N1 treatments reduced the amylose contents and the head rice rates of the two rice types and the chalky rice rate of Wenjiang rice, whereas they increased the chalky rice rate and chalkiness ratio of Shehong rice. Compared with that of PASP-urea applied at the basal stage alone and spilt-applied at the basal stage and at panicle initiation, optimized N management of PASP-urea treatment significantly decreased the chalkiness ratio, peak viscosity, and breakdown viscosity, and increased the setback viscosity and grain crude protein contents. At the same time, it reduced the head rice rate and increased the chalky rice rate and amylose content in Wenjiang rice, whereas it reduced the chalky rice rate and increased the head rice rate in Shehong rice. Overall, in terms of the milling quality, appearance, starch RVA, amylose content, and grain crude protein content, the two applications of PASP-urea fertilizer treatment resulted in better comprehensive qualities in Shehong rice, whereas optimized N fertilization treatment gave better comprehensive qualities in Wenjiang rice.

Effects of eleven herbicides on the growth and weed control efficacy in autumn-sown pea

HUANG Qipeng, ZHANG Yating, GONG Xiangwei, XIA Meijuan, REN Huili, LI Zhonghao, FENG Baili, WANG Pengke, GAO Jinfeng

2019, 27(7): 1053-1066. doi: 10.13930/j.cnki.cjea.181103

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Abstract:
Grass damage problems have hindered the spread of peas; chemical herbicides have become an important measure to control weeds on farmlands. However, there is no effective and safe herbicide for controlling weeds in pea fields. So, the study evaluated the effectiveness of 11 herbicides, which included 6 kinds of pre-emergence herbicides (48% trifluralin, 50% acetochlor, 33% pendimethalin, 96% (s)-metolachlor, 50% napropamide, 40% prometryn) and 5 kinds of post emergence herbicides (15% fluazifop-p, 10% quizalofop-p, 12.5% sethoxydim, 10.8% haloxyfop-r-methyl, 12% clethodim), on weed control while cultivating the pea cultivar 'Xiwan-2'. The best concentration of all herbicides was selected, and the clear water application (CK1) and artificial weeding (CK2) as two controls. Field experiments were conducted to investigate weed species, study the effects of different herbicides on weeds control, and discus the effects of herbicides on the growth process, morphological characteristics, and economic benefits of autumn pea. The research showed:1) there were 7 families and 13 species of weeds in autumn pea fields; among them, broadleaf weeds included 9 species accounting for 69.23% of the weeds found. This indicated that weeds species in autumn pea field were more in number and broadleaf weeds were the main ones. Farmers should choose broad-spectrum herbicides based on broad-leaved weeds. Herbicides had different control effects on weed quantity and fresh weight, and there was a positive correlation between them. Among the pre-emergence herbicides, 33% pendimethalin had the best control effect; among the post emergence herbicides, 12% clethodim had the best control effect. 2) From overwintering to flowering, herbicide treatments had significant effects on plant height and relative chlorophyll content of autumn pea; however, from the beginning of the pod stage, the effect was no longer significant. All treatments inhibited the accumulation of dry matter in root, stem, and leaf of autumn pea to varying degrees; at the same time, the rate of movement and translocation of dry matter in stem and leaf organs of autumn pea treated with different herbicides were higher than that of artificial weeding, and the rate of movement and translation of dry matter in leaf was higher than that in stem. 3) Herbicides had no significant effect on yield components such as 100-grain weight and pod length. In addition to a slight decrease in yield caused by 10.8% haloxyfop-r-methyl, the other herbicides showed a certain increase in production; among them, 33% pendimethalin and 12% clethodim could increase the yield of autumn peas by more than 25%. The net income from all herbicide treatments increased; among them, the net income of 33% pendimethalin and 12% clethodim was the highest among the herbicides evaluated. It can be seen that the use of herbicides helps increase the economic benefits to farmers. Combined with efficacy, safety, and economic benefits of herbicides, the synthetic effect of pre-emergence herbicide 33% pendimethalin and post emergence herbicide 12% clethodim in autumn pea fields was the best among all herbicides tested. Under the experimental conditions aimed at controlling weeds in the autumn pea field, use of pre-emergence herbicide 33% pendimethalin and post emergence herbicide 12% clethodim is recommended.

Trend of agricultural plantation and irrigation requirements in the upper reaches of Xiong'an New Area

BAI Zhijie, REN Dandan, YANG Yanmin, HU Yukun, YANG Yonghui

2019, 27(7): 1067-1077. doi: 10.13930/j.cnki.cjea.190323

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Abstract:
The agriculture is a major consumer of water. Since Xiong'an New Area is facing serious water shortage and groundwater declining, it is necessary to optimize the scale of upstream agriculture water use. By using crop models for simulating the irrigation requirements of wheat and maize, and taking the Pan-evaporation coefficient (K_p) approach to estimate the irrigation requirement of other crops, such as vegetables and fruit trees, our study reconstructed the spatial and temporal trend of agriculture plantation and irrigation requirement in the upper reaches of Xiong'an New Area from 1970. The proportion of irrigation requirements and time-dependent changes of different crops formed a clear trend. The results showed that the total planting area generally increased. There was no significant change in the area of cultivated land and the effective irrigated area. The average cultivated area for many years was 849 000 hm², while the effective irrigated area averaged 713 000 hm², accounting for 84% of the total cultivated land area. The planting area of wheat decreased slightly, the planting areas of maize and vegetables increased significantly, and the planting proportion of fruit trees increased in the mountain area and decreased in the plain area. The annual average irrigation requirement was 22.52×10⁸ m³, of which wheat, maize, vegetables, fruit trees, and other crops accounted for 58.6%, 12.6%, 5.8%, 16.3%, and 6.7% of the total irrigation requirement, respectively. The irrigation requirement of vegetables and fruit trees increased significantly, and was affected by the increase in planting area. Spatially, the total irrigation requirement increased significantly in the mountain area but decreased in the plain area. After elimination of the influence of annual precipitation fluctuation, the irrigation requirement showed a sharply increasing trend from 1970 to 2015, but slowed down in the mid-1980s. Owing to the increase of planting area and irrigation requirements of vegetables and fruit trees, the irrigation requirement showed a slow increasing tendency overall. Therefore, controlling the agricultural water use in the upper mountainous reaches of Xiong'an New Area, planting of low-water-consuming crops and reducing the planting area of water-consuming crops are keys to restoring water production for Xiong'an New Area. Finally, the sustainable utilization of regional water resources should be based on local natural conditions and the layout of agricultural production should be arranged in accordance with the spatial and temporal distribution of water resources to seek a coordinated development for the water-ecology-social economy of Xiong'an New Area.

Characteristics of resource allocation and utilization of rice-wheat double cropping system in the Jianghuai Area

DU Xiangbei, KONG Lingcong, XI Min, WU Wenge, CHEN Jinhua, YUE Wei

2019, 27(7): 1078-1087. doi: 10.13930/j.cnki.cjea.181114

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Rice-wheat double cropping system is the main cropping pattern in the Jianghuai Area. The characteristics of natural resource allocation and utilization and their relationship with yield are still unclear. It is necessary to establish a quantitative evaluation index system for the systematic guidance of the double cropping system. In this study, resources distribution between two seasons, resources utilization efficiencies, and yield of rice-wheat double cropping system in three regions of the Jianghuai Area:along Huaihe River region (AHR), Jianghuai region (JH), and along Yangtze River region (AYR), were quantitatively analyzed using the large database created from high yield field experiments during 2008-2017. The results were as follows:radiation during wheat season and per year decreased in the region, while in the rice season radiation increased in AHR and JH but decreased in AYR. The accumulated temperature increased in wheat season and decreased in rice season, and the annual accumulated temperature increased in AHR and decreased in JH and AYR. Precipitation during wheat season, rice season, and per year increased. The annual radiation in the Jianghuai area increased from the north to the south with no significant difference between japonica rice-wheat system and indica rice-wheat system. The radiation distribution rate of wheat season and rice season were 53.1% and 51.9%, respectively, for the japonica rice-wheat double cropping system, and 55.0% and 49.8%, respectively, for the indica rice-wheat double cropping system. The cumulative accumulated temperature and precipitation gradually increased from the north to the south of Jianghuai area, with no significant difference between two systems, but there were significant differences between different regions. The distribution rate of accumulated temperature in wheat and rice season were 38.5% and 67.3%, respectively, for the japonica rice-wheat, and were 40.7%, 65.1%, respectively for the indica rice-wheat double cropping system. The accumulated precipitation distribution rate of wheat season and rice season were 32.8% and 70.5%, respectively, for the AHR region; 40.8% and 64.7% respectively, for the JH region; and 46.2%, 57.2%, respectively, for the AYR region. Under the current production pattern, rice production had the highest yield proportion of the wheat-rice double cropping system, with an average of 57.0%. The temperature production efficiency in wheat season was higher in AHR than in JH and AYR; during rice season this did not change greatly between the two systems and among the three regions. The annual temperature production efficiency order for the three regions was:AHR > JH > AYR. Radiation use efficiency of crops was not different for different seasons. The rain production efficiency in wheat and rice seasons and per year was significantly lower in AYR than both in AHR and JH. Rice production in the JH region was mainly affected by radiation, and wheat production was mainly affected by rainfall, which limited further increase in crop yield potential. Climate change effects tended to be unfavorable to the evolution of climate resources in the future. When compared with wheat, rice had higher efficient utilization of radiation resources, which was important for improving yield and the resource use efficiency of rice-wheat double cropping system in the JH region. Based on the analysis, we put forward the principle of annual high efficiency utilization, because radiation was the main factor between the two wheat-rice double cropping system, when considering rainfall and growth degree-days. Cultivation measures such as sowing date adjustment and annual cultivars combination can allocate more resources to rice season, thus improving the yield and resource utilization efficiency.

Variation in groundwater resources carrying capacity in Beijing between 2001 and 2015

GAO Fei, WANG Huixiao, LIU Changming

2019, 27(7): 1088-1096. doi: 10.13930/j.cnki.cjea.181107

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Owing to the over-extraction of groundwater resources in Beijing over the past 40 years, Beijing has faced an increasingly sharp decline in groundwater level and storage. Few studies have been reported the variation of groundwater resources carrying capacity in Beijing. In this paper, groundwater resources carrying capacity was defined and assessed based on the available groundwater quantity and water use efficiency. Our results indicated that the water supply from groundwater in Beijing was higher than that from surface water. The agricultural water use efficiency and industrial water use efficiency increased from 2001 to 2015, except other industries water use efficiency decreased slightly from 2014 to 2015. The comprehensive water efficiency increased from 97 ¥·m^-3 to 620 ¥·m^-3 between 2001 and 2016. Our results also showed that the actual GDP supported by the groundwater resources increased from 2 636 million Yuan to 11 469 million Yuan and then decreased to 11 284 million Yuan. Before 2010, groundwater resources in Beijing were overloaded, but this alleviated after 2010. Although the actual GDP supported by groundwater resources was lower than theoretical GDP, groundwater resources had faced a serious situation; therefore, increase in the surface water supply and improvement of the comprehensive water efficiency would be two effective ways to improve groundwater resources management in Beijing.

Effects of rainfall and runoff on the groundwater quality in farmland and poplar forestland in the area of Hung-tse Lake

LI Jiping, XU Yongfeng, CHEN Zipeng, LI Wei, LI Pingping, HAN Jiangang

2019, 27(7): 1097-1104. doi: 10.13930/j.cnki.cjea.181049

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Abstract:
The loss of nitrogen and phosphorus in agriculture has become an important cause of groundwater pollution. To explore and compare the losses of nitrogen and phosphorus from runoff in wheat fields, rice fields, and poplar forestland, the surface nutrient losses and groundwater quality were monitored in the area of Hung-tse Lake for one year, by setting up monitoring plots and monitoring wells on farmland and poplar forestland. The main results were as follows:1) the surface soil water content before and after precipitation in the forestland was lower than that in the wheat field. The average soil water content in wheat fields was 8.95% higher than that before rain, whereas it was 4.05% higher than that before rain in forestland. 2) The total loss of nitrate nitrogen, ammonium nitrogen, and available phosphorus in the surface soil of the wheat field were 63.53 mg·kg^-1, 5.61 mg·kg^-1, and 57.43 mg·kg^-1; while those in the poplar forestland were 16.78 mg·kg^-1, 2.45 mg·kg^-1, and 0.73 mg·kg^-1, respectively. The total loss of nitrate nitrogen, ammonium nitrogen, soluble phosphorus, and particulate phosphorus in the surface water of the rice field was 8.32 mg·L^-1, 27.44 mg·L^-1, 2.39 mg·L^-1, and 2.99 mg·L^-1, and the total loss of nitrogen and phosphorus in the poplar forestland was significantly lower than that in the farmland during the monitoring period. 3) There was a close relationship between the soil nutrient loss and rainfall in farmland. The soil nutrient loss in farmland increased logarithmically with an increase in rainfall. However, the loss of surface nutrients in the poplar forestland was almost unaffected by rainfall. 4) The theoretical minimum rainfall generating runoff in farmlands (wheat field:3.3 mm; rice field:4.2 mm) was much lower than that of the poplar forestland (22.8 mm). The concentration of ammonium nitrogen, orthophosphate, total nitrogen, nitrate nitrogen, total phosphorus, and soluble phosphorus were significantly correlated with rainfall in wheat field. 5) There was a significant correlation between the nutrient concentrations in farmland runoff and nitrogen and phosphorus contents in groundwater (P < 0.05). The nitrogen and phosphorus contents in the groundwater of poplar forestland, which had no significant correlations with the nutrient concentrations in the runoff, remained at a relatively stable level. Compared with farmlands, forestland can better control nutrient losses caused by runoff, alleviate groundwater pollution, and contribute to the control of agricultural non-point source pollution.

Spatial and temporal changes in carbon footprint for oilseed rape production in the middle and lower reaches of Yangtze River during 2004-2015

CHEN Zhongdu, XU Chunchun, JI Long, FANG Fuping

2019, 27(7): 1105-1114. doi: 10.13930/j.cnki.cjea.181025

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Abstract:
The Yangtze River is one of the major oilseed rape producing areas in China. It is therefore of great significance to analyze the carbon footprint of oilseed rape, for developing low-carbon agriculture and for climate change mitigation in this region. Based on the statistical data of sown area, crop yield, and farmland investment of oilseed rape production along the Yangtze River, the spatiotemporal dynamic change in carbon footprint and its composition of oilseed rape during 2004-2015 in the middle and lower reaches of Yangtze River was estimated using the theory of carbon footprint and life cycle assessment method in the agricultural sector. The results showed the carbon footprint of oilseed rape at first decreased and then increased, the lowest point being 2 177.6 kg·hm^-2 in 2013. The main components of the carbon footprint for oilseed rape production were fertilizer (50.9%-53.1%) and labor (5.8%-8.4%). Obvious differences were found among main agricultural provinces in the study area. The carbon footprint per unit area (CF_a) and per unit yield (CF_y) of Jiangsu and Zhejiang Provinces were higher, while that of Hunan and Jiangxi Provinces were lower. What was more, the CF_a and CF_y in high yield regions were significantly higher than that in low yield regions. Among them, the carbon footprint of nitrogenous fertilizer, phosphate fertilizer, and compound fertilizer was significantly higher than that for low-yielding provinces, which increased by 81.7%, 81.2%, and 112.8%, respectively, (P < 0.05). The results suggest that improving crop management practices that limit fertilizer consumption and strengthen mechanical integration technology to reduce labor costs could help mitigate greenhouse gas emissions from oilseed rape production along the middle and lower reaches of Yangtze River.

Progress and outlook of agricultural ecological footprints

LIU Yu, MA Yanji

2019, 27(7): 1115-1123. doi: 10.13930/j.cnki.cjea.180998

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Abstract:
As an effective metrology tool to assess the sustainable development of agriculture, the agricultural ecological footprint has been widely adopted by scholars worldwide due to the model's high operability and result comparability. In the process of its development, the combination of the agricultural ecological footprint with other measurement methods, such as the energy theory, life cycle theory, input-output method, scenario simulation, etc., has provided an effective approach for sustainable agricultural development. In recent years, the contribution of agriculture to the GDP in China has been declining. Sustainable agricultural development and management are very important aspects for China to solve the "Three Rural Issues", which have already become extremely worthy of attention and research. Agriculture has its peculiarities. On the one hand, agricultural activities consume raw materials and energy resources. On the other hand, agriculture also yields products in addition to agricultural wastes and pollutants. Therefore, the agricultural ecological footprints are different from the ecological footprints of other industries. Based on the concept of agricultural ecological footprints, this article reviewed the domestic and international researches on the algorithm for agricultural ecological footprints, parameter adjustments, and application of agricultural ecological footprints for assessing sustainable agricultural development. In terms of the algorithm, this paper summed up four perspectives:1) only considering the agricultural consumption of biological resources, 2) simultaneously considering the agricultural consumption of both biological resources and energy, 3) considering agricultural waste and pollutants, and 4) combining other measurement methods. We also summarized the general methods for adjusting the parameters of agricultural ecological footprints. The paper also discussed the general methods for adjusting the parameters of agricultural ecological footprints, including the general methods for the adjustment of the yield (YF) and equivalence factors (EQF). In addition, this paper reviewed the impact of different agricultural technologies and modes of agricultural production on agricultural ecological footprints, as well as the application of agricultural ecological footprints for the sustainable development of agriculture. This research showed that scholars worldwide had made a series of empirical explorations in the fields related to agricultural ecological footprints, thus making significant progress. In terms of the algorithm, researchers had begun to improve the original algorithm from the traditional model of agricultural ecological footprints. In terms of parameter adjustments, scholars had constantly adjusted the YF and EQF to make the results closer to the reality of local agricultural development. In terms of the application, scholars had taken agroecology as the main line and combined social, economic, and technological dimensions to comprehensively study agricultural sustainable development.

Establishment and assessment of management systems for wheat and maize with high yield and nitrogen use efficiency based on GIS at the village level

LI Yanan, WANG Haodan, QU Hongrui, CAO Hongzhu, TONG Bingxin, CUI Shilei, HAN Yanru, MA Wenqi

2019, 27(7): 1124-1133. doi: 10.13930/j.cnki.cjea.190144

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Abstract:
Smallholder farmers are the main body of agricultural production in China, but there are big variations in the crop yields and efficiency of resource utilization among these farmers. To increase the yield and nutrient use efficiency of crops and ensure precise management of smallholders' plots, this research established a management system for wheat and maize that produces high yield and nitrogen use efficiency at the village level, based on GIS using C# language. The verification of system effects was carried out through the field comparative test on the farmland and a feasibility evaluation was conducted by investigating farmers. During the farmer survey, the farmers were classified into 3 categories, which included the test farmers in whose fields the comparative test was conducted, radiation farmers who often interacted with researchers, and ordinary farmers who were not influenced by researchers. The results showed that the management system, based on peasant household plots, created high yield and nitrogen use efficiency for each farmer in the village, through information queries, data analyses, management decision making, system management, and other functional modules. The results of 22 comparative experiments in two years showed that, compared with the farmers practice treatment (FP), the treatment with high yield and nitrogen use efficiency (DH), recommended by the system, increased the winter wheat yield and partial nitrogen fertilizer productivity (PFP_N) by 10.8% and 28.5%, respectively. The treatment system (DH) recommended during the maize season increased the yield and PFP_N by 10.3% and 16.9%, respectively. This indicated that, with technological support from the recommendation system, farmers could be increasing their yield and nitrogen use efficiency of the winter wheat and summer maize, simultaneously. The results of the farmers' investigation showed that smallholders had a high degree of recognition for the management system, making it feasible to use the system for technical recommendations. Farmers had a high recognition for the recommended technologies for winter wheat and summer maize, but the adoption rate varied greatly. In particular, the adoption rate of recommended wheat varieties was 94%, but the adoption rate of precision sowing technology for winter wheat was 29%. The adoption rate of densification technology and late harvest technology of summer maize was only 2% and 35%, respectively. The recognition and adoption rates of the test and radiation households, which were greatly influenced by the technical recommendations made by the scientific and technical personnel, were higher than that of the ordinary peasant households. This indicated that it was feasible to popularize the management system to peasant households. In conclusion, the management system of winter wheat and summer maize for high yield and nitrogen use efficiency incorporated the auxiliary decision-making of crop management technology for smallholder plots, and had a significant effect on increasing the yield and nutrient use efficiency, which provided the possibility of achieving high crop yield and nutrient efficiency in large areas.

Measurements and influencing factors of the efficiency of environmental-ly-friendly agricultural production in Sichuan Province based on SE-DEA and spatial panel STIRPAT models

XIONG Ying, XU Yusha

2019, 27(7): 1134-1146. doi: 10.13930/j.cnki.cjea.180857

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Abstract:
Environmentally-friendly agriculture complies with the current urgent need for green agricultural development. However, the existing research into environmentally-friendly agriculture lacks analysis on productivity improvement. Sichuan is a major agricultural province of China. A quantitative analysis on the efficiency of Sichuan's environmentally-friendly agricultural production and its influencing factors may provide a scientific basis for the development of environmentally-friendly agriculture in Sichuan. This will also enrich the knowledge about environmentally-friendly agriculture from the perspective of production efficiency. Based on panel data from 21 regions in Sichuan Province from 2006 to 2016, Super-Efficiency Data Envelopment Analysis (SE-DEA) models were applied to measure the production efficiency of environmentally-friendly agriculture. A theoretical model for the factors influencing the production efficiency of environmentally-friendly agriculture was established and a Spatial Durbin Model (SDM) was used for empirical analysis based on the STIRPAT theoretical model. The results showed that the production efficiency of environmentally-friendly agriculture in Sichuan Province first decreased and then increased between 2006 and 2016. It decreased from 0.708 in 2006 to 0.667 in 2009, then gradually increasing to 0.805 in 2016. The average efficiency of environmentally-friendly agricultural production in Sichuan during these 11 years was 0.705. The overall level was low and significant differences existed in each region. The highest average production efficiency in Ya'an and Aba reached 0.981, while the minimum in Guangyuan was 0.458. Meanwhile, the average production efficiency, in areas such as Luzhou, Mianyang, Leshan, Yibin, Guang'an, Bazhong, Nanchong, Meishan, and Guangyuan, was lower than 0.6, which was caused by the excessive input of chemical fertilizers, pesticides, and agricultural films. The agricultural labor and proportion of grain-sown area in the total crop area had significant direct effects on the production efficiency of environmentally-friendly agriculture. The coefficients for these two factors were 0.158 and 0.506, respectively. The population density and proportion of grain-sown area in the total crop area had significant indirect effects on the production efficiency of environmentally-friendly agriculture. The coefficients for these factors were 0.988 and 1.366, respectively. Additionally, the population density in neighboring regions had spillover effects among regions, which created competition for the limited agricultural resources in this region, resulting in negative indirect effects. The changes of planting structures in neighboring regions affected the adjustment of the planting structure in this region, resulting in negative indirect effects. Because that there were not only significant differences in the production efficiency of environmentally-friendly agriculture in each region of Sichuan, but also spatial spillover effects among the regions, the direct effects of regional internal factors and interactive effects of the factors among the regions should be considered during the formulation of environmentally-friendly agricultural development policies in various regions of Sichuan Province.

2019 Vol. 27, No. 7