Effects of reducing N, straw returning and dicyandiamide application on winter wheat yield and nitrogen budgets in rain-fed region.

Abstract

In a 3-year field experiment, effects of reducing N fertilizer, straw returning and dicyandiamide (DCD) application on wheat yield and nitrogen budgets under wheat-fallow system were studied in rain-fed region. The experiment was carried out in Yangling of Shaanxi Province, and 4 treatments were installed including no nitrogen (CK), 220 kg N·hm-2 and no straw returning (FP), 150 kg N·hm-2 and straw returning (OPT), 150 kg N·hm-2, 7.5 kg·hm-2 DCD and straw returning (OPT+DCD). The results showed there was no remarkable difference for wheat yield between OPT and FP, but the N use efficiency of the former was 6.1% more than that of the latter, and the apparent N loss ratio was 7.2% less. OPT+DCD increased the average yield of winter wheat by 10.4% and 7.9% respectively compared to OPT and FP, the N use efficiency of winter wheat increased by 20.8% and 28.1%, and the apparent N loss ratio decreased by 8.5% and 15.1%, respectively. NH4+-N content in 0-20 cm of soil increased, accordingly the NO3--N content decreased in 40 to 45 days when DCD was applied.