Russian N fertilization trials are a valuable data source for Nitrogen Use Efficiency concept

Abstract

Based on the results of fertilization trials with winter wheat on sod-podzolic soils and on chernozems, we have analysed agronomical benefits and environmental threats of increasing N rates in the mineral and mixed organic-mineral fertilizer systems with Nitrogen Use Efficiency (NUE) approach. For the Non-Chernozem zone a safe N rates are within 100-150 kg·ha-1 for mixed organic-mineral fertilization system and 120-180 kg·ha-1 for a mineral fertilization system. This indicates the lower availability of N applied with organic fertilizers and the smaller aftereffect of the applied organic N. Consistency of the results of short-term and long-term experiments reveals the importance of significant soil mineralization processes providing reserves of mineral N for winter wheat. “Safe operating space” was higher for chernozems -200-250 kg·ha-1 with lower response to N fertilizer application than for sod-podzolic soils as a result of the higher role of soil N stock. The study also demonstrates the applicability of the NUE indicator for connecting N efficiency and yield sustainability. A noticeable decrease in variation between years in N output occurs when the input is > 100 kg·ha-1, suggesting increasing N fertilization in improving yield sustainability. At the same time, for winter wheat growing technologies of 70-80s last century as well for the modern ones rates > 250 kg·ha-1 demonstrate N excess and higher environmental N losses.