Effects of NMUrea on rice yield and agronomic nitrogen efficiency

The study was conducted to investigate the effects of the NMUrea on rice yield and agronomic efficiency of nitrogen fertilizer (NAE) of the high-yield-cultivar Wandao153 in 2009. The results show that comparing with the normal urea treatments, the tiller numbers, SPAD values, accumulation amounts of dry matter are increased significantly under the NMUrea treatments with the same nitrogen rate. Meanwhile, the grain yields of the NMUrea treatments are larger than those of the normal urea treatments when the nitrogen rates are from 0 to 90 kg/ha, but the differences are not significant, while the grain yields and NAE of the NMUrea treatments are increased significantly when the nitrogen rates are further increased, and the grain yield is increased by 10.2% and NAE is increased by 44.5% in their maxima. Based on the developed model between the yield and the fertilizer rate, the agronomic efficiencies of the normal urea are only 58.3%-87.6% of those of the NMUrea when the nitrogen rates are from 90 to 244.9 kg/ha, and the NMUrea can save 12.4%-41.7% of nitrogen. It is suggested that the NMUrea treatment with N 244.9 kg/ha is the perfect treatment for high-grain-yield cultivation, and has the highest grain yield of 11174.7 kg/ha and a much higher NAE, and the NMUrea treatment with N 180 kg/ha is the perfect treatment for safe cultivation, has much higher grain yield and NAE.