Accounting for differences between crops and regions reduces estimates of nitrate leaching from nitrogen-fertilized soils
Yan Wang, Yihong Liu, Longlong Xia, Hiroko Akiyama, Xinli Chen, Ji Chen, Yunying Fang, Tony Vancov, Yongfu Li, YuanZhi Yao, Dianming Wu, Bing Yu, Scott X. Chang, Yanjiang Cai
Abstract
Nitrate (NO3−) leaching from nitrogen (N) fertilized soils is a significant global concern, affecting both the environment and public health. However, substantial uncertainties and variabilities in NO3− leaching factors (LFs) among regions or crops impede accurate assessments of NO3− leaching. Here we synthesize 2500 field observations worldwide and show that LFs vary by an order of magnitude across regions and crops, primarily driven by hydroclimatic and edaphic conditions rather than N fertilizer management. Global cropland NO3− leaching from synthetic N fertilization, calculated through spatially explicit (15.4, 14.8–16.1 Tg N yr–1) and crop-specific (12.9, 11.0–14.8 Tg N yr–1) LFs, is 41% lower than the Intergovernmental Panel on Climate Change Tier 1 global inventory. Over 47% of this leaching is concentrated in China, India, and the United States, with maize, wheat, rice and vegetables accounting for nearly half of it. Improved regional and crop-specific LFs will provide a benchmark for NO3− leaching abatement by pinpointing potential global hotspots. Almost half of globally leached nitrate from nitrogen-fertilized soil is released in China, India, and the United States, according to a meta-analysis covering 2500 field observations worldwide.