Assessment of nitrate leaching loss on a yield-scaled basis from maize and wheat cropping systems.

摘要

Background and aims: It is so far a gap in knowledge to assess nitrate (NO₃-) leaching loss linking with crop yield for a given cereal cropping system. Methods: We conducted a meta-analysis on 32 published studies reporting both NO₃- leaching losses and crop yields in the maize (N=20) and wheat (N=12) systems. Results: On average, 22% and 15% of applied fertilizer N to wheat and maize systems worldwide are leached in the form of NO₃-, respectively. The average area-scaled NO₃- leaching loss for maize (57.4 kg N ha-1) was approx. two times higher than for wheat (29.0 kg N ha-1). While, if scaled to crop yields, the average yield-scaled NO₃- losses were comparable between maize (5.40 kg N Mg-1) and wheat (5.41 kg N Mg-1) systems. Across all sites, the lowest yield-scaled NO₃- leaching losses were observed at slightly suboptimal fertilization rates, corresponding to 90% and 96% of maximum maize or wheat yields, respectively. Conclusions: Our findings suggest that small adjustments of agricultural N management practices can effectively reduce yield-scaled NO₃- leaching losses. However, further targeted field experiments are still needed to identify at regional scale best agricultural management practices for reducing yield-scaled NO₃- leaching losses in maize and wheat systems.