Fertilization with a new type of coated urea: Evaluation for nitrogen efficiency and yield in winter wheat

Three years field experiments were conducted from 1999 to 2002 to evaluate winter wheat (Triticum aestivum L.) yield, nitrogen efficiency (NE) including nitrogen efficiency ratio (NER), nitrogen uptake efficiency (NUpE), nitrogen use efficiency (NUE), and nitrogen fertilizer use efficiency (Nf UE) Lis influenced by a new coated urea as CRF. Results showed that both coated urea and common urea treatments produced significant higher biomass, grain, and straw yields, and higher NUE and nitrogen fertilizer recovery rate over the control. The maximum yield and nitrogen (N) efficiency were observed in the treatment of coated urea in the three years. On average, the grain, straw, and biomass yield of coated urea treatment was 9.09-15.06, 13.11-14.96, and 11.73-14.99% higher than those of common urea respectively. The coated urea not only resulted in higher yield, but nitrogen fertilizer recovery rate (Nf UE) of the treatment was 16.50-68.72% more than that of common urea treatment. Compared to normal dosage of N fertilization (150 kg N ha(-1)) insufficient amount increase of N fertilizer (8% increase) does not affect both yield and NE. However, sufficient amount increase of N fertilizer (20% higher) can result in significant increase of yield, N uptake and N fertilizer recovery rate (Nf UE) under the experiment condition.