Effects of different rice straw on soil microbial community structure

Straw incorporation is an important measure to improve soil fertility and soil acidification. However, fresh straw that is returned to the field cannot be decomposed in a short time. Accumulation of undecomposed straw in the soil changes humus composition and the C structure. An experiment was designed to evaluate the effects of decomposed straw on soil fertility and microbial communities. Soil samples were collected from a rice-rice-tobacco region in southwestern China (The rice was Hongyou No 7, which was a new variety applied in 2007 by the Honghe State Agricultural Science Institute,Yunnan province, China). (The tobacco was K326. K326 was an excellent variety which Imported from Northup King Seed Company (USA) to China in 1985). The soil was mixed with different kinds of straw and incubated in a greenhouse. The responses of the soil fertility, microbial diversity, and microbial population were analyzed after 0, 16, and 33 d of incubation. Overall, we found that (a) the soil organic matter and the organic C content of each humus component were significantly increased after 33 d of incubation. In addition, the condensation and oxidation degrees of the soil C structure were decreased. (b) Community dynamics changes in the soil were accompanied by changes of incubation times. (c) Decomposed straw incorporation could stimulate potentially beneficial microbial populations. (d) Decomposed straw incorporation with microbial agent application could be the best practice for the application of biofertilizers.