Effects of Mixed Addition of Green Manure on Soil Traits and Tobacco Quality

In order to understand the ecological benefit of green manures with different addition patterns on tobacco growing soil, a series of experiments was carried out. Briefly, green manures including Astragalus sinicus, Lolium perenne, and the mixed A. sinicus and L. perenne by a ratio of 3:1 were ploughed back and dynamic changes of various soil traits such as nutrients, activities of multiple enzymes and microbial biomass were measured during 120 days after treatments. The results indicated that the mixed addition treatment could significantly increase the content of soil available phosphorus between 30 and 60 days, from 43.86 mg/kg to 58.61 mg/kg, while adding A. sinicus or L. perenne alone had no significant effect. Compared with the single addition treatments, the mixed addition treatment can significantly increase the content of soil microbial biomass (MBC, MBN and MBP), activities of soil urease and diastase between 60 and 120 days. In addition, the main tobacco chemical indexes (nitrogen, tobacco nicotine, K and the ratio of K to Cl) detected under the mixed addition treatment were better than those under the single addition of A. sinicus or L. perenne treatments, reaching the standards of high quality tobacco. In summary, it is suggested that the mixed addition of green manure is conducive to release more nutrients to tobacco growing soil and promote tobacco growth, better than single green manure additions.