Effect of fertilizing patterns on grain yield,nutrient uptake and economical efficiency of double-season rice

Effect of fertilization on double-season rice yield,nutrient uptake and economic benefit under paddy-upland rotation was studied through a long-term field experiment during 2005 to 2008.The result showed that grain yields were significantly increased by combined application of nitrogen(N),phosphorus(P) and potassium(K) fertilizers.The effect of chemical fertilizers plus organic fertilizer[1/2(M+F)]on grain yield became more significant as the planting seasons continued.The grain yield of early and late rice under 1/2(M+F) treatment was increased to 135% and 130% respectively,over the CK treatment.The uptake of nutrients(N,P and K) increased in both straw and grains,with the corresponding increase in yield,which indicates the positive correlation between grain yield and nutrient uptake.Different fertilizing patterns greatly affected nutrient contents(N,P and K) in the plant.The chemical fertilizers plus organic fertilizer treatment promoted rice nutrient uptake and reduced residual N and P in the soil,compared with that in other treatments.Relatively higher net incomes were obtained from NPK and 1/2(M+F) treatments in despite of higher inputs.It's recommended to apply chemical fertilizers plus organic fertilizer and increase P and K in double-season rice production.