Effect of topdressing time of nitrogen fertilizer and controlled-release coated urea on winter wheat yield and apparent nitrogen recovery rate

Pot experiments were used to investigate the effect of topdressing time of nitrogen fertilizer and application of controlled-release coated urea on wheat yield, yield component, apparent nitrogen recovery rate and apparent soil nitrogen loss. The results show that jointing stage is the best time for topdressing of nitrogen fertilizer in winter wheat. Compared with 40% basal and 60% topdressing urea (F2) at jointing stage, nitrogen release trend of 30% urea, 35% coated urea with a release time of 90 d, and 35% coated urea with release time of 120 d (F4, F6) mixed basal application is more or less the same as that of plant nitrogen requirement. The total nitrogen accumulation under F4 (with normal N dose) increases by 6.11%, while under F6 (with 75% of normal N dose) increases by 8.48% compared with F2. Wheat yield, economic coefficient and apparent nitrogen recovery rate increase by 5.02%, 6.43% and 10.22% under F4 respectively. Furthermore, apparent soil nitrogen loss decreases. F4 increases yield by improving 1000-grain weight and single spike weight, F6 guarantees the yield through maintaining the grain number per spike.