稻草还田对土壤微生物群落功能多样性的影响

为了探讨稻草还田的微生物学过程与效应,借助平板涂抹法和BIOLOG检测法,比较研究了免耕条件下3种不同稻草还田量(33%、67%和100%,以稻草不还田土壤为对照)对晚稻田土壤微生物群落功能多样性的影响.结果表明:①土壤细菌数量差异显著,以67%稻草还田处理为最高,稻草不还田处理最低,稻草还田提高了土壤细菌数量;②碳源平均颜色变化率(AWCD法)在培养早期各处理间的差异不大,但随着培养时间的延长,67%和100%稻草还田处理土壤微生物的AWCD值显著大于对照和33%稻草还田处理组;③土壤微生物代谢多样性指数(丰富度和多样性)在3种稻草还田量处理土壤中也表现出明显差异,67%和100%稻草还田处理的土壤中微生物功能多样性显著大于33%稻草还田处理和对照;④67%和100%稻草还田处理显著改善了土壤微生物的功能多样性.以67%稻草还田处理改善土壤微生物群落结构和功能的效果最为显著.

Effects of rice-straw returning to the field on the metabolic diversity of soil microbial communities

To evaluate the effects of returning rice-straw to the field on the soil microbial community, the soil microbial communities under three proportions of rice-straw returning to the field (T1: 33%; T2: 67%; T3:100%; CK: 0) were measured. Bacterial amount and metabolic diversity (BIOLOG) assays were performed and significant differences were found in bacterial amount among the three treatments. The two indicators were the highest in T2, and lowest in CK. In the BIOLOGassays, average well colour development (AWCD) and the indices of richness and diversity indicated differences of microbial metabolic diversity. The indices were significantly higher in the soils of T2 and T3 than in CK, suggesting that the ability to utilize carbon sources and the functional diversity were greater in these soils than in T1 and CK. Altogether, bacterial amount and metabolic diversity patterns in soil T2 were dominant, and returning rice-straw to the field improves the structure and function of soil microbial community, especially at a 67% proportion.