Effects Of Intercropping And Straw Returning On Soil Physical Character And Soil Organic Carbon

The black soil in Northeast China is one of the three black soil bands in the world..But over the years, unreasonable cultivation, poor management, coupled with soil erosion and other reasons,make the soil fertility of black soil is seriously decreased in recent years, The agricultural production capacity as before.Soil organic matter is the source of life of the soil, Soil organic carbon determines the level of soil fertility. The change of the ecosystem carbon pool will affect the soil fertility, and then affect the crop yield.Aiming at this problem, this study through field experiment mainly discusses intercropping and straw-returning to field conditions, on soil organic matter and soil active organic carbon, water solution of organic carbon, microbial biomass carbon, readily oxidized organic carbon these activity was higher in the organic carbon and soil humus carbon these stable state carbon influence.Research results show that:1.Each treatments were higher than contrast in soil water content,straw + chemical fertilizer reatment, melilotus + straw + chemical fertilizer treatment, Melilotus + straw + 1/2chemical fertilizer treatment soil water content were higher than that of conventional chemical treatment,Melilotus + straw is 8% higher than contrast chemical treatment in 2014. The soil water content was positively correlated with soil organic matter. The soil bulk density and specific gravity of each treatment were decreased compared with the contrast,at the same time increase the soil porosity, obviously improve the physical and chemical properties of the soil.2.Intercropping and straw-returning could increase soil organic matter content, melilotus +straw + chemical fertilizer treatment and straw + chemical fertilizer treatment to improve the effect of soil organic matter is best,they are all higher than the conventional fertilizer treatment, and Melilotus + straw treatment soil organic matter content is higher than that of the control, they were4% and 6% higher than contrast in 2 years.3.The active fraction of soil organic carbon in the conventional fertilizer treatment was higher than that in the control,but lower than the straw + chemical fertilizer treatment and melilotus +straw + chemical fertilizer treatment and melilotus + straw + 1/2chemical fertilizer treatment,melilotus + straw treatment of microbial biomass carbon and active organic carbon and light fraction organic carbon was higher than that of conventional chemical fertilizer treatment,the content of water soluble organic carbon was lower than that of conventional chemical fertilizertreatment; soil organic matter was positively correlated with the active organic carbon, and positively correlated with the microbial biomass carbon.4.Straw + chemical fertilizer treatment and melilotus + straw + chemical fertilizer treatment and melilotus + straw + 1/2chemical fertilizer treatment of mineral organic carbon soil humus carbon and soil heavy fraction organic carbon content were higher than that of the conventional fertilizer treatments and contrast.5.straw + chemical fertilizer treatment, melilotus + straw + chemical fertilizer treatment carbon mineralization are enhanced than conventional fertilizer treatments and contrast. Straw +melilotus + chemical fertilizer treatment is 8% higher than contrast. Melilotus + straw +1/2chemical fertilizer treatment, melilotus + straw treatment and conventional fertilizer treatment soil carbon mineralization were higher than contrast.6.Straw + chemical fertilizer treatment and melilotus + straw + chemical fertilizer treatment and melilotus + straw + 1/2chemical fertilizer treatment and melilotus + straw treatment carbon pool activity and carbon lability index and soil carbon pool management index were higher than the control, chemical fertilizer treatment was higher the control, straw + chemical fertilizer treatment and melilotus + straw + chemical fertilizer treatment and melilotus + straw +1/2chemical fertilizer treatment and melilotus + straw treatment are higher than that of the conventional fertilizer treatment in carbon pool activity, melilotus + straw treatment is 9% higher than conventional fertilizer in carbon management index. Intercropping and straw-returning is better than chemical fertilizer in soil carbon pool management index.