Effects of Combined Application of Organic Fertilizer and Chemical Fertilizer on Double Cropping Rice Nutrient Utilization and Leaching Loss from Paddy Soil

Field plot trial was conducted to study the effects of applying straw,pig manure,manure compost or biogas manure combined chemical fertilizer on double cropping rice nutrient utilization and leaching loss from paddy field.Results showed that combination of organic fertilizer and chemical fertilizer improved the contents of N,P,K and organic matter in the pady soil,reduced the concentration of total nitrogen,total phosphorus,ammonium nitrogen and nitrate nitrogen in leachate,promoted rice nutrient absorbtion and utilization.One year later,compared with single application of chemical fertilizer,combination of manure composting nitrgen by 20% and chemical nitrgen by 80% showed a lot of advantages,which obviously increased the contents of TN,TP,TK and organic matter in paddy soil by 2.59%,0.87%,0.15% and 21.45%,alkali-hydrolyzable nitrogen,available phosphorus and available potassium was also increased by 3.31%,3.22% and 12.24% respectively;the utilization ratio of nitrogen,phosphorus and potassium increased by 5.22%,0.55% and 3.50%,respectively;the accumulation of nitrogen,phosphorus and potassium increased by 7.83,0.33,3.14 g/kg;the concentration of TN,TP,NH+4-N,NO-3-N in leachate decreased obviously;the early rice yield increased by 19.65%,while late rice yield decreased indistinctively.