Fertilizing Efficiency of Middle-late Rice under Tobacco-rice Rotation System in Jinchenshi Town

In order to study influences of different fertilizing treatments on yield of late rice under tobacco-rice rotation system,the fields developed from different mother materials under tobacco-rice rotation system in Shaoyang city were chosen to conduct field fertilizing experiments with 3414 method in 2012.The results showed that the fertility contribution for yield of late rice had relatively huge difference between different experiment sites,which was between 38.5% and 82.3%.Applying nitrogen fertilizer and phosphor fertilizer had obvious yield increasing effects that the yield increased by 53.5% and 11.3%,respectively;the unit nutrients increased by 13.5 kg/kg and 9.9 kg/kg,respectively;but applying kalium fertilizer had relatively worse yield increasing effects that the yield increased by only 5.2%;the unit yield increased by 2.4 kg/kg;and the partial plots appeared yield reduction.With increasing fertilizer rate of N,P and K,yield of late rice showed tendency of increasing first and then decreasing.Based on a single-variable quadratic equation model,the optimal estimated economic fertilizer rate of N,P2O5 and K2O was 160.7 kg/hm2,37.1 kg/hm2 and 40.3 kg/hm2,respectively.Therefore,the fields under tobacco-rice rotation system should reduce fertilizer rate of P and K.