土壤质地对秸秆分解的影响及其微生物机制

Effects of Different Soil Textures on Decomposition of Straw and Its Microbial Mechanism

本研究以河南省封丘县的砂质、壤质、黏质潮土为对象,基于网袋秸秆埋设法,比较分析了经半年埋设后小麦和玉米秸秆分解速率变化,及基于磷脂脂肪酸(PLFA)的微生物组成差异。结果表明:秸秆分解率在不同质地潮土间无显著性差异;残留秸秆中碳含量与原始秸秆相当,表明秸秆分解过程中碳按比例减少;但氮和磷含量显著增加,尤其在质地黏重的土壤处理中更为明显。经半年埋设,小麦和玉米秸秆中钾的释放比例分别高达99%和97%。PLFA结果显示,两种秸秆中的细菌、真菌、放线菌在砂、壤、黏土处理间无显著差异,表明影响秸秆分解的微生物生物量在不同土壤质地处理间相当,这可能是导致秸秆在不同质地潮土中分解率无显著差异的原因之一;但PCA分析表明,参与小麦和玉米秸秆分解的微生物种类有所不同,其差别主要与革兰氏阳性菌14:0、i14:0、3OH-16:0、i17:0,革兰氏阴性菌cy17:0以及放线菌10Me18:0有关。

Plot experiment was conducted to study the effects of soil textures （sand, loam and clay） on the straw decomposition using litter bag method and the microbial components using phospholipid fatty acid （PLFA） method at Fengqiu Ecological Experimental Station of Chinese Academy of Sciences. The results showed that the decomposition rate of straw was not significantly affected by the soil texture. Total C content of the residual straw was similar to the original straw, indicating that total C content of straw scaled down during the decomposition. N and P contents the residual straw increased significantly, especially in the loam and clay soils. Total K content of wheat and maize straw was significantly lower than original straw in all soil textures, and the release rate was as high as 99% and 97% after six months, respectively. PLFA analysis showed no significant differences in bacteria PLFA, fungi PLFA and the total PLFA among the three soil textures, which may be attributed to the similar decomposition rate of straw in three soil textures. The principal component analysis （PCA） showed that microbes participating in wheat and maize straw decomposition were different in gram-positive bacteria （14：0, i14：0, 3OH-16：0, i17：0）, gram-negative bacteria （cy 17：0）, and actinomycctes （10Me 18：0）.