Nitrogen retention within a watershed reduces the amount of N exported to the ocean;however, it worsens environmental problems, including surface water eutrophication, aquifer pollution, acid rain, and soil acidificat...Nitrogen retention within a watershed reduces the amount of N exported to the ocean;however, it worsens environmental problems, including surface water eutrophication, aquifer pollution, acid rain, and soil acidification. Here, we adopted the Soil and Water Assessment Tool(SWAT) model to describe the riverine N output and retention effects in the Shanmei Reservoir Basin, a subtropical mountainous basin located in Quanzhou City, Southeast China. The results revealed that farmlands and orchards in the upstream and central parts of the basin were the dominant land use types, which contributed large N yields. Fertilizer application was the key source of riverine N output and N retention within the basin. On average, approximately 64% of anthropogenic N inputs were retained within the basin, whereas 36% of total N was exported to the downstream and coastal areas. The average N retention efficiency was 80% in a dry year, and within the year, N retention occurred in spring and summer and N release occurred in autumn and winter. The annual variation in N retention within the basin was largely dominated by changes in rainfall and runoff, whereas the seasonal characteristics of N retention were mainly affected by fertilization. Even with a large decrease in fertilizer application, owing to the contributions of the residual N pool and river background, the riverine N output still maintained a certain base value. The effects of precipitation, land use types, and agricultural fertilizer on N retention should be comprehensively considered to implement reasonable N management measures.展开更多
Rice yields and nitrogen use efficiencies were studied at five sites in southwest China using two nitrogen fertilization rates and five controlled-release urea（ CRU） to ordinary urea（ U） ratios. The fertilizer tre...Rice yields and nitrogen use efficiencies were studied at five sites in southwest China using two nitrogen fertilization rates and five controlled-release urea（ CRU） to ordinary urea（ U） ratios. The fertilizer treatments significantly increased rice yields compared with the control（ no nitrogen added） yields to different degrees at different sites. Applying CRU and U increased the rice yield more than adding the same amount of nitrogen as U only. Higher increasing production rate were found using a nitrogen application rate of 105 kg/hm2 than 150 kg/hm2. A 70∶ 30 CRU∶ U ratio increased the yield more than other four ratios. Nitrogen use efficiency was 21. 9% higher using a nitrogen application rate of 105 kg/hm^2 than 150 kg/hm^2,and 46. 6%,38. 1%,34. 7%,and 22. 2% higher than when only U was applied when CRU∶ U ratios of 70 ∶ 30,50 ∶ 50,100 ∶ 0,and 30 ∶ 70,respectively,were used. A 70 ∶ 30 CRU ∶ U ratio gave the highest economic output（ yuan/hm^2）. Applying both CRU and U gave an output 3 078. 87 yuan/hm^2 higher at a nitrogen application rate of 150 kg/hm^2 than at a nitrogen application rate of 105 kg/hm^2. Economic output was always higher using both CRU and U than using U only. The highest economic output was given using a 70∶ 30 CRU∶ U ratio.Increasing the amount of nitrogen added decreased the output efficiency（ per hm2） because CRU is expensive. Significant relationships were found between the yield increase rate and the proportion of CRU added（ regression equation y = 7. 429 x-185. 7,R^2= 0. 663） and between the total rainfall over the whole growth period and the proportion of CRU added（ y =-0. 087 1 x ＋ 112. 29,R^2= 0. 687 9）. These regression equations can be used to determine the appropriate proportion of CRU that should be added at a site,depending on the rainfall and target rice yield.展开更多
在群体水培条件下,以国内外不同年代育成的常规籼稻代表品种(2001年为88个、2002年为122个)为材料,测定干物重、氮素含量、产量及其构成因素等,采用组内最小平方和的动态聚类方法将供试品种的氮素籽粒生产效率(NUEg)从低到高依次分为A、...在群体水培条件下,以国内外不同年代育成的常规籼稻代表品种(2001年为88个、2002年为122个)为材料,测定干物重、氮素含量、产量及其构成因素等,采用组内最小平方和的动态聚类方法将供试品种的氮素籽粒生产效率(NUEg)从低到高依次分为A、B、C、D、E和F 6种类型,研究不同氮素籽粒生产效率类型品种氮素分配与运转的基本特点。结果表明,供试品种间NUEg的差异很大(244%、325%),A、B、C、D、E和F类品种的平均NUEg,2001年分别为20.51、31.04、35.64、39.46、43.55、50.92 g g-1,2002年分别为24.33、31.61、35.83、39.06、43.51、50.00g g-1;NUEg高的品种抽穗期、成熟期茎鞘叶中氮素比例小、穗中氮素比例大,成熟期更明显,结实期茎鞘叶氮素运转量大、运转率高;提高结实期茎鞘叶氮素运转量和运转率有利于提高结实期茎鞘叶干物重运转量和经济系数。展开更多
基金funded by the National Key Research and Development Program of China (2018YFE0206400)the National Natural Science Foundations of China (41601535 and 41807159)。
文摘Nitrogen retention within a watershed reduces the amount of N exported to the ocean;however, it worsens environmental problems, including surface water eutrophication, aquifer pollution, acid rain, and soil acidification. Here, we adopted the Soil and Water Assessment Tool(SWAT) model to describe the riverine N output and retention effects in the Shanmei Reservoir Basin, a subtropical mountainous basin located in Quanzhou City, Southeast China. The results revealed that farmlands and orchards in the upstream and central parts of the basin were the dominant land use types, which contributed large N yields. Fertilizer application was the key source of riverine N output and N retention within the basin. On average, approximately 64% of anthropogenic N inputs were retained within the basin, whereas 36% of total N was exported to the downstream and coastal areas. The average N retention efficiency was 80% in a dry year, and within the year, N retention occurred in spring and summer and N release occurred in autumn and winter. The annual variation in N retention within the basin was largely dominated by changes in rainfall and runoff, whereas the seasonal characteristics of N retention were mainly affected by fertilization. Even with a large decrease in fertilizer application, owing to the contributions of the residual N pool and river background, the riverine N output still maintained a certain base value. The effects of precipitation, land use types, and agricultural fertilizer on N retention should be comprehensively considered to implement reasonable N management measures.
基金Supported by Study and Mode Construction of Water and Fertilizer Coupling and Accurate Fertilizer and Drug Reduction High-yielding Synergistic Technology during Diversified Rice Planting in the West Part of the Middle and Lower Reaches of the Yangtze River(2017YFD0301700)National System of Rice Industrial Technology(CARS-01-25)
文摘Rice yields and nitrogen use efficiencies were studied at five sites in southwest China using two nitrogen fertilization rates and five controlled-release urea（ CRU） to ordinary urea（ U） ratios. The fertilizer treatments significantly increased rice yields compared with the control（ no nitrogen added） yields to different degrees at different sites. Applying CRU and U increased the rice yield more than adding the same amount of nitrogen as U only. Higher increasing production rate were found using a nitrogen application rate of 105 kg/hm2 than 150 kg/hm2. A 70∶ 30 CRU∶ U ratio increased the yield more than other four ratios. Nitrogen use efficiency was 21. 9% higher using a nitrogen application rate of 105 kg/hm^2 than 150 kg/hm^2,and 46. 6%,38. 1%,34. 7%,and 22. 2% higher than when only U was applied when CRU∶ U ratios of 70 ∶ 30,50 ∶ 50,100 ∶ 0,and 30 ∶ 70,respectively,were used. A 70 ∶ 30 CRU ∶ U ratio gave the highest economic output（ yuan/hm^2）. Applying both CRU and U gave an output 3 078. 87 yuan/hm^2 higher at a nitrogen application rate of 150 kg/hm^2 than at a nitrogen application rate of 105 kg/hm^2. Economic output was always higher using both CRU and U than using U only. The highest economic output was given using a 70∶ 30 CRU∶ U ratio.Increasing the amount of nitrogen added decreased the output efficiency（ per hm2） because CRU is expensive. Significant relationships were found between the yield increase rate and the proportion of CRU added（ regression equation y = 7. 429 x-185. 7,R^2= 0. 663） and between the total rainfall over the whole growth period and the proportion of CRU added（ y =-0. 087 1 x ＋ 112. 29,R^2= 0. 687 9）. These regression equations can be used to determine the appropriate proportion of CRU that should be added at a site,depending on the rainfall and target rice yield.
文摘在群体水培条件下,以国内外不同年代育成的常规籼稻代表品种(2001年为88个、2002年为122个)为材料,测定干物重、氮素含量、产量及其构成因素等,采用组内最小平方和的动态聚类方法将供试品种的氮素籽粒生产效率(NUEg)从低到高依次分为A、B、C、D、E和F 6种类型,研究不同氮素籽粒生产效率类型品种氮素分配与运转的基本特点。结果表明,供试品种间NUEg的差异很大(244%、325%),A、B、C、D、E和F类品种的平均NUEg,2001年分别为20.51、31.04、35.64、39.46、43.55、50.92 g g-1,2002年分别为24.33、31.61、35.83、39.06、43.51、50.00g g-1;NUEg高的品种抽穗期、成熟期茎鞘叶中氮素比例小、穗中氮素比例大,成熟期更明显,结实期茎鞘叶氮素运转量大、运转率高;提高结实期茎鞘叶氮素运转量和运转率有利于提高结实期茎鞘叶干物重运转量和经济系数。
