田间条件下小麦和玉米秸秆腐解过程中微生物群落的变化——BIOLOG分析

对秸秆分解微生物演变机理的研究是调控秸秆还田、提高农田地力的理论基础。本试验基于土壤置换试验平台,利用BIOLOG方法研究在寒温带、中温带和中亚热带气候下,埋于黑土、潮土和红壤中的小麦和玉米秸秆在腐解过程中微生物对碳源利用的变化规律。试验中利用网袋法区分直接分解秸秆微生物。试验结果发现秸秆腐解微生物的碳源代谢活性(Average Well Color Development AWCD值表示)在腐解0.5 a和1 a后表现出一定的随气候变化规律,即随温度和降雨量的增加而降低。其中0.5 a为海伦(0.765±0.060)>封丘(0.737±0.165)>鹰潭(0.326±0.076),1 a为海伦(0.630±0.092)>封丘(0.319±0.096)>鹰潭(0.291±0.029),但这种趋势在腐解2 a后减弱。气候条件是影响秸秆腐解微生物碳源代谢活性的主要因素,其次是腐解时间和土壤类型。主成分分析表明在腐解0.5 a后海伦、封丘地区的微生物群落代谢特征与鹰潭差异较大,而1 a后封丘和鹰潭的微生物群落代谢特征与海伦的差异较大,腐解2 a后不同气候条件下的秸秆腐解微生物对碳源的利用趋于一致,均对含氮化合物利用较多。

Changes of microbial communities during decomposition of wheat and maize straw: analysis by BIOLOG

The study on mechanism of the evolution of straw-decomposing microbes is the theoretical basis for regulating straw incorportion and raising soil fertility in farmland. A reciprocal translocation experiment was set to investigate changes in metabolic activity (expressed as AWCD, Average Well Color Development) during decomposition of maize stalk and wheat straw in Phaeozem, Cambisol and Acrisol under cold temperate, warm temperate and mid-subtropic climate conditions. Litter bag method was used to avoid mixing with soil in identifying microbial communities responsible for straw decomposition. Results show that AWCD decreased with the increase in temperature and rainfall in treatments of half-a-year and one-year decomposition, following an order of Hailun (0.765?0.060) > Fengqiu (0.737?0.165) > Yingtan (0.326?0.076), and an order of Hailun (0.630?0.092) > Fengqiu (0.319?0.096) > Yingtan (0.291?0.029), respectively. However the tendency weakened after two years of decomposition. Obviously climate is the key factor that influences microbial activity in carbon utilization. In addition, the principal component analysis revealed that the soils from Hailun and Fengqiu varied sharply from that from Yingtan in metabolic properties of microbial communities after 0.5 year of decomosition, and tended to be simillar after two years of decomposition regardless of climate conditions. They all used more of nitrogen-containing compounds.