Effects of stabilized nitrogen fertilizer application amount and application methods on yield and nitrogen efficiency of rice.

A rice field experiment was carried out in Anhui Province in 2014 to investigate the effects of stabilized N fertilizer (SNF) application amount and its application methods on rice yield, nitrogen accumulation, nitrogen use efficiency (NUE) of rice, economic efficiency and soil nutrients. Compared with non-stabilized nitrogen fertilizer, the yield of SNF treatments as 100% one application, 100% split application, 85% one application and 70% N one application increased 53.1%, 61.6%, 39.7% and 36.7% respectively, total N accumulated by aboveground parts increased 64.0%, 80.9%, 36.0% and 32.3%, and economic benefits increased 50.4%, 59.5%, 37.4% and 34.5% respectively. Compared with local farmer fertilizer practice, the yield of SNF treatments as 100% and 100% split application increased 5.7% and 11.6% respectively. Total N absorbed by aboveground parts increased 9.9% and 21.2%, and economic benefits increased 5.8% and 12.2% respectively. At the same N application amount, SNF with 100% promoted rice yield and N accumulation compared with farmer fertilizer practice and the split application had even more significant difference. The nitrogen apparent efficiency and nitrogen agronomic efficiency of SNF with 100% was higher than farmer fertilizer practice and the split application had even more significant difference. The three treatments of nitrogen physiological efficiency and nitrogen partial factor productivity had no significant difference. SNF could increase soil available nitrogen content, which was increased with the increasing application amount. Based on rice yield and NUE, the optimum SNF application amount was 240 kgN·hm-2 with the ratio of basal fertilizer to tiller fertilizer of 6:4.