Amino acid value-added urea reduces fertilizer-derived nitrogen loss in paddy soil by enhancing plant uptake, soil retention, and microbial turnover: Evidence from 15N tracing.

High nitrogen inputs have led to improved agricultural productivity, but have also caused a range of environmental issues. How to promote the nitrogen fertilizer use efficiency and reduce active nitrogen losses in agricultural systems is vital for the sustainability of intensive agriculture. In this study, the effects of a new nitrogen fertilizer, amino acid value-added urea, on fertilizer nitrogen loss, residue and bioavailability were evaluated by a rice-leaching column incubation experiment combined with 15N isotope tracing technology. The results indicated that the value-added urea with amino acid significantly reduced fertilizer-driven nitrogen losses by 27.6 ± 13.4% (p < 0.05) at high N levels (30 g m- 2), and 85.5 ± 17.1% of this reduction was contributed by N leaching. The increase of fertilizer nitrogen in plant uptake (33.6 ± 18.2%) and soil residues (21.8-28.4%) were directly related to fertilizer nitrogen losses and are essential factors to explain the decline in N losses. Moreover, amino acid-enhanced urea significantly increased soil N residues by promoting the utilization of fertilizer N by microbial residues, which indirectly contributed to the reduction of fertilizer N losses. This study provided detailed data and theoretical basis for the further improvement and efficiency technology of nitrogen fertilizer.