Effect Of Combined Application Of Pig Manure Compost And Inorganic Fertilizers On Rice-Wheat Growth And Soil Fertility

A field experiment was carried out to investigate the effects of different combined applications of pig manure compost (PMC) and chemical fertilizers (CF) on rice-wheat yield, nutrients accumulation, nitrogen use efficiency and soil fertility. There were four treatments including combined application of PMC and CF (PMC3000kg/hm2+70%NPK), for PMCF1, combined application of PMC and CF (PMC6000kg/hm2+50%NPK), for PMCF2, organic and inorganic compound fertilizers with PMC and CF1800kg/hm2, for PMC1and organic and inorganic compound fertilizers with PMC and CF1800kg/hm, for PMC2. The results are as follows:When the application of total nitogen fertilizer rate was240kg/hm2, the crop yield was increased by5.2%in rice season and4.0%in wheat season, respectively, as comparing with the chemical fertilizer (nitrogen fertilizer240kg/hm2). While the nitrogen fertilizer application rate was reduced by5%(228kg/hm2) and10%(216kg/hm2), the crop yield obtained by the combined application of PMC and CF (PMC3000kg/hm2+70%NPK, for PMCF1and organic and inorganic compound fertilizer with PMC and CF1800kg/hm2, for PMC1) and chemical fertilizer was the same. When total organic and inorganic compound fertilizer N application rate was increased to432kg/hm2(PMC2), the crop yield was tended to be increased, but had no significance.The treatments of combined applications of pig manure compost (PMC) and chemical fertilizers (CF) showed higher crop nitrogen, phosphorus and potassium nutrient accumulation. In rice season, except for the PMC2, other combined applications of PMC and CF showed higher N and P harvest index than chemical fertilizers. In wheat season, except for the PMC2, there were no significant differences between the chemical fertilizer and other treatments on nutrient harvest index. Expet for the PMC2, the rice nitrogen use efficiency of combined application of PMC and CF was higher than chemical fertilizer treatment, and the highest nitrogen use efficiency was gained by PMC1treatment. In rice season, nitrogen recovery efficiency increased22.6%,0.2%and80.4%in PMCF1, PMCF2and PMC2treatments, respectively, while in wheat season this increased30.5%,13.0%and 87.8%in PMCF1, PMCF2and PMC2treatments, respectively.The effects of combined application of PMC and CF treatments on soil mineral nitrogen content and available nutrient were significantly different. For rice-wheat rotation soil, compared with chemical fertilizer treatment, PMC2treatment had high soil available nutrient and stable soil mineral nitrogen supply. But most of them may be lost in the field and the crops used less amount. While the nitrogen fertilizer application rate was reduced by5%(228kg/hm2) and10%(216kg/hm2), soil available nutrient and soil mineral nitrogen supply was the same as the chemical fertilizer.The correlation among microbiological characteristics was significant. Compared with chemical fertilizer, the effect of organic fertilizer application was more obvious on soil microbial biomass carbon, nitrogen, phosphorus, soil urease and phosphatase activity. The effect of treatment PMC2on soil microbial biomass carbon, nitrogen, phosphorus, soil urease and phosphatase activity was more significant as compared with other treatments.In conclusion, while the nitrogen fertilizer application-rate was reduced by5%-10%, using combined application of PMC with CF or making the organic and inorganic compound fertilizer can satisfy the requirement of the crop yeild in rice-wheat rotation system of South Jiangsu province.