Fates of 15N-labeled fertilizer in a black soil-maize system and the response to straw incorporation in Northeast China

Abstract

Purpose: Over-fertilization has caused low nitrogen (N) use efficiency and N pollution in China. A better understanding of the fate of fertilizer N is critical for improved appropriate N management practices. Materials and methods: We examined the fate of urea-N applied to a typical black soil-maize system and the response to straw incorporation in Northeast China using the field 15N labeling technique. Large plots (25 m2) were used to reduce artificial disturbance and facilitate multiple samplings in one growing season. Results and discussion: We found that of the applied N (200 kg N ha−1), 52% was taken up by crops at harvest and 24% was retained in the soil (0–40 cm). The unrecovered 23% ..