Effects of delayed release coated urea on rice growth and nitrogen absorption

In order to increase crop production and maximize nitrogen utilization efficiency, field experiments were conducted to investigate the effect of urea and delayed release coated urea under different conditions (with different dose and applied methods) on the growth and nitrogen uptake of transplanted rice. Urea(U) was applied in conventional way (basal dressing plus twice topdressing) with the nitrogen application rate being 150 kg per hectare, while delayed release coated urea was applied with single basal in nursery bed using contact placement method with by single basal application and nitrogen application rate of two coated urea treatments(N0.5,N0.7) was 75 and 105 kg per hectare respectively. The results showed that there was no negative impact on rice growth using delayed release coated urea with contact placement. Coated urea increased rice yield, nitrogen absorption and nitrogen utilization efficiency significantly. Comparing the (effects) of coated urea with urea, rice yield increased by 12.7%14.4%, nitrogen absorption increased by 27.5%32.7%. The nitrogen utilization efficiency was 19.9%, 89.9%, 58.8% for urea, coated urea with 50% application reduction and 70% application reduction respectively. Meanwhile, grain protein content with coated urea promoted by 9.2%12.2%.