A high crop yield with the minimum possible cost to the environment is generally desirable.However,the complicated relationships among crop production,nitrogen(N) use efficiency and environmental impacts must be clear...A high crop yield with the minimum possible cost to the environment is generally desirable.However,the complicated relationships among crop production,nitrogen(N) use efficiency and environmental impacts must be clearly assessed.We conducted a series of on-farm N application rate experiments to establish the linkage between crop yield and N_2 O emissions in the Guanzhong Plain in Northwest China.We also examined crop yield,partial factor productivity of applied N(PFPN) and reactive N(Nr) losses through a survey of 1 529 and 1 497 smallholder farms that grow wheat and maize,respectively,in the region.The optimum N rates were 175 and 214 kg ha^(-1) for winter wheat and summer maize,respectively,thereby achieving the yields of 6 799 and 7 518 kg ha^(-1),correspondingly,with low N_2 O emissions based on on-farm N rate experiments.Among the smallholder farms,the average N application rates were 215 and 294 kg ha^(-1) season^(-1),thus producing 6 490 and 6 220 kg ha^(-1) of wheat and maize,respectively.The corresponding PFPN values for the two crops were 36.8 and 21.2 kg N kg^(-1),and the total N_2 O emissions were 1.50 and 3.88 kg ha^(-1),respectively.High N balance,large Nr losses and elevated N_2 O emissions could be explained by the overdoses of N application and low grain yields under the current farming practice.The crop yields,N application rates,PFPN and total N_2 O for wheat and maize were 18 and 24% higher,42 and 37% less,75 and 116% higher,and 42 and 47% less,correspondingly,in the high-yield and high-PFPN group than in the average smallholder farms.In conclusion,closing the PFPN gap between the current average and the value for the high-yield and high-PFPN group would increase crop production and reduce Nr losses or the total N_2 O emissions for the investigated cropping system in Northwest China.展开更多
In the northwestern part of China,rational and efficient management of irrigation and nitrogen significantly affects the intensive production of greenhouse cucumbers(Cucumis sativus L).To evaluate the effects of diffe...In the northwestern part of China,rational and efficient management of irrigation and nitrogen significantly affects the intensive production of greenhouse cucumbers(Cucumis sativus L).To evaluate the effects of different combinations of water use and nitrogen(N)on yield,quality,and profitability of the greenhouse cucumbers that planted in 2018 Spring,nine combined treatments were applied.Results indicated the optimal irrigation and nitrogen demands for yield,quality and other indicators were different.The irrigation amount significantly affected the yield,and the yield gradually increased with increasing in irrigation.Single fruit weight(SFW)was significantly affected by the amount of irrigation,nitrogen and their interactions,and the higher amounts of N and irrigation were beneficial to the increase of SFW.The partial factor productivity of the applied N(PFPN)gradually increased with the nitrogen amount decline.Irrigation water use efficiency(IWUE)was closely related to the amount of irrigation.The higher irrigation amount would lead to the lower IWUE.When the amounts of irrigation and nitrogen were at an intermediate level,the content of vitamin C(VC)reached the maximum.As the amount of nitrogen was increased or irrigation was decreased,the Nitrate content(NC)would increase.Free amino acid(FAA)and NC followed a similar variation.When the amounts of irrigation and nitrogen both were at medium levels,the total soluble sugar concentration(TSSC)reached the highest.The multi-level fuzzy evaluation method was used to evaluate different indicators of cucumber.The weights of indicators in the first and second layer were determined by analytic hierarchy process(AHP)and entropy weight method,respectively.Then the fuzzy algorithm was used to comprehensively evaluate all the treatments.The evaluation results show that T4(irrigation,1957.6 m3/hm2;N,210 kg/hm2)is the best strategy for greenhouse cucumber irrigation and nitrogen management in the northwestern part of China.展开更多
基金the National Key Research and Development Program of China (2016YFD0800105)
文摘A high crop yield with the minimum possible cost to the environment is generally desirable.However,the complicated relationships among crop production,nitrogen(N) use efficiency and environmental impacts must be clearly assessed.We conducted a series of on-farm N application rate experiments to establish the linkage between crop yield and N_2 O emissions in the Guanzhong Plain in Northwest China.We also examined crop yield,partial factor productivity of applied N(PFPN) and reactive N(Nr) losses through a survey of 1 529 and 1 497 smallholder farms that grow wheat and maize,respectively,in the region.The optimum N rates were 175 and 214 kg ha^(-1) for winter wheat and summer maize,respectively,thereby achieving the yields of 6 799 and 7 518 kg ha^(-1),correspondingly,with low N_2 O emissions based on on-farm N rate experiments.Among the smallholder farms,the average N application rates were 215 and 294 kg ha^(-1) season^(-1),thus producing 6 490 and 6 220 kg ha^(-1) of wheat and maize,respectively.The corresponding PFPN values for the two crops were 36.8 and 21.2 kg N kg^(-1),and the total N_2 O emissions were 1.50 and 3.88 kg ha^(-1),respectively.High N balance,large Nr losses and elevated N_2 O emissions could be explained by the overdoses of N application and low grain yields under the current farming practice.The crop yields,N application rates,PFPN and total N_2 O for wheat and maize were 18 and 24% higher,42 and 37% less,75 and 116% higher,and 42 and 47% less,correspondingly,in the high-yield and high-PFPN group than in the average smallholder farms.In conclusion,closing the PFPN gap between the current average and the value for the high-yield and high-PFPN group would increase crop production and reduce Nr losses or the total N_2 O emissions for the investigated cropping system in Northwest China.
基金This work was partially supported by the Key Research and Development Program of Shaanxi Province in China(Grant No.2018TSCXL-NY-05-03)the Xi'an Science and Technology Program in China(Grant No.2017050NC/NY011(2))the Key project for Innovation in Production,Education and Research of Yangling in China(Grant No.2017CXY-07).
文摘In the northwestern part of China,rational and efficient management of irrigation and nitrogen significantly affects the intensive production of greenhouse cucumbers(Cucumis sativus L).To evaluate the effects of different combinations of water use and nitrogen(N)on yield,quality,and profitability of the greenhouse cucumbers that planted in 2018 Spring,nine combined treatments were applied.Results indicated the optimal irrigation and nitrogen demands for yield,quality and other indicators were different.The irrigation amount significantly affected the yield,and the yield gradually increased with increasing in irrigation.Single fruit weight(SFW)was significantly affected by the amount of irrigation,nitrogen and their interactions,and the higher amounts of N and irrigation were beneficial to the increase of SFW.The partial factor productivity of the applied N(PFPN)gradually increased with the nitrogen amount decline.Irrigation water use efficiency(IWUE)was closely related to the amount of irrigation.The higher irrigation amount would lead to the lower IWUE.When the amounts of irrigation and nitrogen were at an intermediate level,the content of vitamin C(VC)reached the maximum.As the amount of nitrogen was increased or irrigation was decreased,the Nitrate content(NC)would increase.Free amino acid(FAA)and NC followed a similar variation.When the amounts of irrigation and nitrogen both were at medium levels,the total soluble sugar concentration(TSSC)reached the highest.The multi-level fuzzy evaluation method was used to evaluate different indicators of cucumber.The weights of indicators in the first and second layer were determined by analytic hierarchy process(AHP)and entropy weight method,respectively.Then the fuzzy algorithm was used to comprehensively evaluate all the treatments.The evaluation results show that T4(irrigation,1957.6 m3/hm2;N,210 kg/hm2)is the best strategy for greenhouse cucumber irrigation and nitrogen management in the northwestern part of China.
