Effects Of Fertilizers On Early And Late Rice Under Condition Of Reddish Clayey Soil And Masa Mud Soil In Xiangtan City

This study based on soil testing and fertilizer recommendation project in Xiangtan City. The "3415" designed filed experiments were conducted to investigate the yield increasing effect of nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer and organic fertilizer on double cropping rice. We established a fertilization effect model on double rice system and put forward some scientific fertilization suggestions. The main results are as follows:1. For the reddish clayey soil, the soil capability yield, soil fertility rate, yield increasing effects of organic and chemical fertilizer for early rice were4582.8kg/hm2,65.44%,10.40%and24.16%, and for late rice were5276.5kg/hm2,65.94%,7.34%,26.72%, respectively; the soil capability yield and yield increasing effects of chemical fertilizer for early rice were lower than late rice, soil fertility rate and yield increasing effects of organic for early rice were higher than late rice. For masa mud soil, the soil capability yield, soil fertility rate, yield increasing effects of organic and chemical fertilizer for early rice were4553.0kg/hm2,63.79%,11.46%,24.75%, and for late rice were4927.5kg/hm2,65.80%,6.73%,27.48%, respectively; the soil capability yield, soil fertility rate and yield increasing effects of chemical fertilizer for early rice were lower than late rice, yield increasing effects of organic for early rice were higher than late rice.2. Significantly increase in both early and late rice yield was observed after the application of nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer. On both tested soils, the agronomic efficiencies of nitrogen, phosphorus and potassium were9.59～12.85kg/kg,11.27∶24.57kg/kg and11.12∶13.91kg/kg, respectively. Different agronomic efficiencies were observed between two tested soils, rice types and among fertilizers types. Moreover, the agronomic efficiencies of nitrogen, phosphorus and potassium reduced with the increasing application amount. The relationships between the yields of both early and late rice and chemical fertilizers application amounts followed the quadratic equation with one unknown (0.9663≤r≤0.9996,p<0.05).3. Chemical fertilizers effect models between chemical fertilizers application amounts and rice yield were fitting with quadratic equation with three unknown. For reddish clayey, the early rice equation was Y=4819.15+14.17N+15.86P+18.27K-0.07N2-0.21P2-0.14K2+ 0.06NP+0.03NK-0.04PK (r=0.9913**) and the late rice equation was Y=5467.79+11.88N+35.68P+15.29K-0.05N2-0.71P2-0.11K2+0.08NP+0.04NK-0.03PK (r=0.9940), respectively. For masa mud soil, the early rice was Y=4808.36+15.01N+21.97P+12.81K-0.08N2-0.32P2-0.12K2+0.06NP+0.06NK+0.01PK (r=0.9866**) and the late rice Y=5096.42+15.87N+38.10P+4.26K-0.05N2-0.54P2-0.09K2-0.07NP+0.05NK+0.13PK (r=0.9955**).4、Based on the chemical fertilizers effect models, we estimated the recommended fertilizers application amounts and best theoretical yield. For early rice on reddish clayey soil were nitrogen fertilizer126.9kg/hm2, phosphorus fertilizer46.3kg/hm2, potassium fertilizer66.1kg/hm2and best rice yield6939.9kg/hm2, respectively. For late rice on reddish clayey soil were nitrogen fertilizer160.0kg/hm2, phosphorus fertilizer31.3kg/hm2, potassium fertilizer80.5kg/hm2and best rice yield7858.9kg/hm2, respectively. For early rice on masa mud soil were nitrogen fertilizer125.0kg/hm2, phosphorus fertilizer44.0kg/hm2, potassium fertilizer70.9kg/hm2and best rice yield6935.6kg/hm2, respectively. For late rice on masa mud soil were nitrogen fertilizer159.1kg/hm2, phosphorus fertilizer31.7kg/hm2, potassium fertilizer82.2kg/hm2and best rice yield7411.3kg/hm2, respectively.