Intercropping Chinese Onion and Potato Increase the Yield of Continuous Soybean

The biological changes in continuous soybean by soybean intercropped with Chinese onion(Allium fistulosum L.),potato(Solanum tuberosum L.),hemp(Cannabis Satia L.) and tobacco(Nicotiana tabacum L.) were investigated in a long-term continuous soybean Mollisols field of Northeast China.The results indicated that compared with soybean monoculture,the yield of continuous soybean was increased by 12% and 9% in Chinese onion/soybean and potato/soybean intercropping systems while it was decreased by 18% and 7.6% in hemp/soybean and tobacco/soybean intercropping systems.Disease severity index of root rot in continuous soybean was decreased by 18.3%,28.5% and 34.2% respectively with increased control effect in Chinese onion/soybean,potato/soybean and tobacco/soybean intercropping systems while it was increased by 10.3% in hemp/soybean intercropping system.Above ground dry matter accumulation at later stage of soybean growth and yield components were all increased significantly in Chinese onion/soybean,and potato/soybean intercropping systems.We conclude that Chinese onion/soybean and potato/soybean intercropping are of values in long-term continuous soybean farmland in Heilongjiang province.