Effects of blended application of coated and common urea on yield, nitrogen use efficiency and ammonia volatilization in winter wheat–summer maize rotation system

Objectives Excessive nitrogen fertilizer application is common in the winter wheat-summer maize rotation system in the North China Plain, causing low nitrogen utilization rate and serious nitrogen loss to the environment. We explored the effects of coapplication of controlled release fertilizer with common urea at different blending ratios on ammonia volatilization loss, annual crop yield and economic benefits, aiming to set up a labor-saving, profitable and environmental-friendly nitrogen fertilization measurement in the grain production of the region.

Methods A field experiment was carried out in the Modern Agricultural Science and Technology Park of Dezhou City from 2022 to 2023. Five treatments were used for both winter wheat and summer maize, including no nitrogen control (CK), conventional nitrogen application (FFP), optimized nitrogen application (OPT), coapplication of coated and conventional urea at blending ratio of 5∶5 for winter wheat and 3∶7 for summer maize (CRBF1), and 7∶3 for winter wheat and 5∶5 for summer maize (CRBF2). The ammonia volatilization was monitored during basal fertilizer and topdressing periods. The plant dry matter accumulation, yield, nitrogen absorption, and fertilization economic benefits were investigated.

Results Compared with FFP, CRBF1 and CRBF2 treatments produced similar maize, wheat, and annual crop yield, and enhanced N partial factor productivity by 8.87−9.86 kg/kg; CRBF1 and CRBF2 treatments increased N recovery efficiency, N agronomic efficiency, and N partial factor productivity by 30.3%−37.2%, 5.22−5.77 kg/kg, and 6.52−7.06 kg/kg in winter wheat, respectively, and RBF2 treatment increased N recovery efficiency by 48.4% in summer maize. Compared with FFP and OPT treatments, CRBF1 and CRBF2 treatments decreased fertilizer and fertilization cost by 381−960 yuan/hm², thereby increased annual net income by 1208−2654 yuan/hm² in two seasons. CRBF1 and CRBF2 treatments significantly reduced annual ammonia volatilization loss by 69.7%−71.9%, ammonia volatilization intensity by 72.0%−74.5%, and ammonia volatilization rate by 90.0%−94.1%, compared to FFP treatment, respectively (P<0.05).

Conclusions Using one-time basal application technology, the recommended blending ratio of coated and common urea is 5∶5 and 3∶7, or 7∶3 and 5∶5 in winter wheat and summer maize season, respectively. The blending ratio is proved of effective in keeping stable annual crop yield, increasing total production benefit, and mitigating ammonia volatilization loss due to reduced nitrogen fertilizer and labor input.