Responses Of Rice Yield And Soil Organic Carbon To Chemical Fertilizer Application Rates Under Utilized The Chinese Milk Vetch

:In order to provide a theoretical basis for paddy fertilizer logistics in the development of Chinese milk vetch recovery process and the carbon cycle in Hunan double rice cropping regions, a located field experiment was carried out to study the effects of chemical fertilizer application rates on double rice of production benefits, and compare the differences of soil organic carbon and labile organic carbon fractions, the organic-inorganic complex status, the combining forms of humus and the quality of soil humus. The results were as follows:1. The utilization of Chinese milk vetch can increase rice yield. Under the condition of milk vetch utilizing, compared with chemical fertilizer only, applying100%mineral fertilizer could increase the total yield of double-rice by7.2%,17.6%respectively in2012and2013. Double cropping of rice production can reduce20-40%NK fertilizer dosage under the condition of Chinese milk vetch utilizing. And the total yield of double-rice of reducing20%NK fertilizer increased by3.9%,17.0%respectively in2012and2013. Reducing40%NK fertilizer basically the same or slightly increased as chemical fertilizer only.2. The utilization of Chinese milk vetch could increase the output value of rice. Under the condition of milk vetch utilizing, compared with chemical fertilizer only, in2012and2013, applying100%fertilizer increased output value of rice by5.9%,14.2%respectively. Appropriate to reduce amount of fertilizers can increase the output value of rice under the utilization of Chinese milk vetch, in2012and2013, the treatment of reducing20%NK fertilizer increased output value of rice by4.1%,14.9%respectively.3. The utilization of Chinese milk vetch can increase the content of soil organic carbon and improve labile organic carbon fractions. The soil organic carbon, labile organic carbon (LOC), moderately labile organic carbon (MLOC), highly labile organic carbon (HLOC) and carbon management index were significant higher in the treatments of applying100%fertilizer and40%fertilizer under the condition of the milk vetch utilizing than fertilizer only. And those of the treatment of reducing20%fertilizer significantly reduced.4. Application of the Chinese milk vetch can ameliorate the organic-inorganic complex status. Under the condition of the milk vetch utilizing, in2012and2013, the content of light fraction organic carbon (LFOC) and heavy fraction organic carbon (HFOC) in soil, the quantity of organo-mineral complex in the treatment of applying100%fertilizer can remarkably increase and the degree of organo-mineral complex decreased significantly than applying chemical fertilizer only. And the treatment of reducing20%appeared to the opposite phenomenon.5. Application of Chinese milk vetch can improve the combining forms of humus in soil. Compared with fertilizer only, in2012and2013, the treatment of applying100%fertilizer could improve the content of Ⅰ C by5.93%and8.39%respectively, and increase the ratio of ⅠC/ⅢC under the condition of milk vetch utilizing. The treatment of reducing20%fertilizer can decrease the content of ⅠC、ⅡC and ⅢC significantly than applying chemical fertilizer only.6. The utilization of Chinese milk vetch could increase the quantity and improve quality of soil humus. Compared with applying chemical fertilizer only, in2012and2013, the soil humic substance extracted carbon (HEC), humic acid carbon (HAC), fulvic acid carbon(FAC) and the ratio of HAC/HEC were significantly higher in the treatment of applying100%fertilizer under the condition of milk vetch utilizing. And the treatment of reducing20%chemical fertilizer decreased significantly as those.To sum up, the treatment of applying100%chemical fertilizer not only can increase the yield of rice and improve the output value of rice, but also ameliorate labile organic carbon fractions, the organic-inorganic complex status and quality of soil humus, and improve the quality of soil.