Study on Soil Nutrient Rich-lack Index and Fertilizer Using Efficiency of Rice in Yunnan Province

By analyzing the results of 303 rice field experiments in Yunnan province,the soil nutrient rich-lack index and fertilizer using efficiency were determined.The results indicated that the nutrient rich-lack index of nitrogen was 65,65-100,100-160,160-250,250 mg/kg with the rank of very low,low,medium,high,very high;and phosphorus rich-lack index was 5,5-10,10-20,20-40,40 mg/kg,and potassium rich-lack index was 30,30-50,50-100,100-150,150 mg/kg.Compared with the Second Soil Survey,the nutrient contents of nitrogen were increased by 40-100 mg/kg,that of phosphorus was the same and potassium were reduced by 50 mg/kg.Fertilizer using efficiency of nitrogen,phosphorus and potassium were 24.7 %,39.9 % and 30.7 %,respectively.