Application of the end-of-season stalk nitrate test for a high-yield maize production system in Northwestern China

摘要

Excessive nitrogen application has caused serious environmental pollution under high-yield maize system in China. Our objective was to evaluate critical stalk nitrate (NO3-) levels that support high yield (>13Mgha(-1)), but are not in excess. Optimal stalk NO3- concentration was determined by conducting seven nitrogen levels experiments in two high yield maize regions: Dongyang County (DY) and Wenshui County (WS). Optimal stalk NO3- concentration category range to obtain maximum yield in DY (sandy loam, higher accumulated temperature and solar radiation compared with WS) was 0.44-1.19, which similar to the criteria of US (0.70-2.0g kg(-1)). While for WS (loam soil, lower accumulated temperature and solar radiation compared with DY), optimal stalk NO3- concentration category range to obtain maximum yield was 1.95-4.15, greatly higher than the US criteria. These results suggested thatit is necessary to establish matching optimal stalk NO3- category ranges for different ecological regions in China.