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|Title:||Fertilizer nitrogen recovery efficiencies in crop production systems of China with and without consideration of the residual effect of nitrogen|
|Authors:||YAN Xiaoyuan; TI Chaopu; VITOUSEK Peter; CHEN Deli; LEIP Adrian; CAI Zucong; ZHU Zhaoliang|
|Citation:||ENVIRONMENTAL RESEARCH LETTERS vol. 9 no. 9 p. 095002|
|Publisher:||IOP PUBLISHING LTD|
|Type:||Articles in periodicals and books|
|Abstract:||China is the world’s largest consumer of synthetic nitrogen (N), where very low rates of fertilizer N recovery in crops have been reported, raising discussion around whether fertilizer N use can be significantly reduced without yield penalties. However, using recovery rates as indicator ignores a possible residual effect of fertilizer N—a factor often unknown at large scales. Such residual effect might store N in the soil increasing N availability for subsequent crops. The objectives of the present study were therefore to quantify the residual effect of fertilizer N in China and to obtain more realistic rates of the accumulative fertilizer N recovery efficiency in crop production systems of China. Long-term spatially-extensive data on crop production, fertilizer N and other N inputs to croplands in China were used to analyze the relationship between crop N uptake and fertilizer N input (or total N input), and to estimate the amount of residual fertilizer N. Measurement results of cropland soil N content in two time periods were obtained to compare the change in the soil N pool. At the provincial scale, it was found that there is a linear relationship between crop N uptake and fertilizer N input or total N input. With the increase in fertilizer N input, annual direct fertilizer N recovery efficiency decreased and was indeed low (below 30% in recent years), while its residual effect increased continuously, to the point that 40%–68% of applied fertilizer was used for crop production sooner or later. The residual effect was evidenced by a buildup of soil N and a large difference between nitrogen use efficiencies of long-term and short-term experiments.|
|JRC Directorate:||Sustainable Resources|
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