Effects Of Intercropping Herbages On Soil Organic Carbon Inapple Orchard Of Wei Bei Loess Plateau

Weibei Loess Plateau is one of the high quality apple producing areas in China the world.But due to the long time traditional clear tillage, results in soil organic matter decrease, soilstructure damaged, degraded of the soil system. These factors became the important cause ofseriously hindered on orchard high quality and high yield and sustainable development.The basic condition to reach the high yield and quality is the orchard soil management, as oneof the mode advanced management of orchard soil, intercropping herbages was been widelyused in fruit production developed countries, our country intrduced it in1998year. Currentresearch on intercropping herbages in orchard mainly focus on the effects of growing herbageon fruit yield, fruit quality, microclimate, and soil environment, while little work was done onthe mechanisms. Intercropping herbages in apple orchard in Weibei Area was studied.Through field experiments and lab analyses, variations in soil organic carbon content, qualityand carbon pool management index were analyzed, and responses of organic carbon tointercropping herbages were discussed. This research provided a scientific basis for studyingthe interaction mechanisms between fruit trees and herbages in the fruit orchard-growingherbage complex system. The main results showed that:1. Soil organic carbon content in0-20cm profile was significantly increased byintercropping herbages, and the increment decreased with soil depth, leading to significantsoil organic carbon differences among soil layers; soil organic carbon density in0-40cmprofile was significantly increased by intercropping herbages, resulting in the distributiondifferences of soil organic carbon density in soil layers; soil C/N ration in0-5cm profile wasalso increased by intercropping herbages, but herbage species had different influences on soilorganic carbon content and density as well as C/N ratio in orchard.2. Light fractions of soil organic carbon and its proportion were significantly increasedby intercropping herbages, and the increment decreased with soil depth especially in the0-20cm layer. The correlation analysis showed that, the accumulation and distribution of soilorganic carbon were significantly affected by light fractions, but growing herbage had littleeffects on heavy fractions of soil organic carbon.3. Chemical composition analysis showed that: Intercropping herbages increased the content of low, moderate, and high activity organic carbon in orchard soil. The increment wasaffected by herbage species, especially in0-20cm soil layer for low and high activity soilorganic carbon and in0-10cm soil layer for moderate activity soil organic carbon. However,intercropping herbages decreased the distribution proportion of low, moderate, and highactivity organic carbon. Correlation analysis showed that low, moderate, and high activityorganic carbon were significantly correlated to total organic carbon, total nitrogen, availablephosphate, available potassium (P <0.01).4. Intercropping herbages significantly increased low and moderate activity soil organiccarbon pool management index (CPMI), and the increment decreased with soil depth. Lowactivity soil CPMI in the0-20cm layer had significant responses, while moderate activity soilCPMI in the0-10cm had significant responses. However, growing herbage had little effectson high activity soil CPMI, and different herbage species had various influences on low,moderate, and high activity soil CPMI. Correlation analysis showed that, soil CPMI hadsignificant correlations with SOC, LOC, NLOC, CPI, available phosphate, and availablepotassium (P <0.01), and with TN (P <0.05), but CPMI had no significant correlation withNO-3-N and NH+4-N.