Soil N transformation mechanisms can effectively conserve N in soil under saturated conditions compared to unsaturated conditions in subtropical China

• DOI: 10.1007/s00374-018-1276-7
• Publication Date: 2018-04-11T09:23:42Z
• Authors: Yushu Zhang; Hong Ding; Xiangzhou Zheng; Zucong Cai; Tom Misselbrook; Alison Carswell; Christoph Müller; Jinbo Zhang
• Keywords: Nitrogen Cycle

The connection between moisture and nitrogen (N) transformation in soils is key to understanding N losses, particularly nitrate (NO3−) also provides a theoretical framework for appropriate water management agricultural systems. Thus, we designed this study provide process-based background decision. We collected soil samples from the long-term field experiment subtropical China, which was examine tobacco rice rotations under monsoon climate. established 2008 with four treatments: (1) no fertilization as control; (2) N, phosphorus (P), potassium (K) fertilizers applied at recommended rates; (3) rates 50% higher than amounts P K (4) P, straw incorporated (NPKS). Soil were during unsaturated tobacco-cropping season saturated rice-cropping incubated 60% holding capacity conditions, respectively. Two 15N tracing treatments (15NH4NO3 NH415NO3) numerical modeling method used quantify transformations gross dynamics. Autotrophic nitrification stimulated by fertilizer both conditions. rate of NO3− consumption (via immobilization denitrification) increased NPKS treatment Secondly, processes associated ammonium (NH4+) cycling, including mineralization organic NH4+ immobilization, dissimilatory reduction NH4+, all conditions relative except autotrophic nitrification. Consequently, NO3−-N NH4+-N concentrations significantly lower resulted reduced risks losses via runoff or leaching. Our results suggest that there conservation mechanism alleviates potential risk