免耕秸秆还田和传统耕作方式下东北黑土氨基糖态碳的积累特征

以吉林德惠市中层黑土进行7年田间定位试验的小区土壤为研究对象,对免耕(NT)和传统耕作下(CT)耕层(0～20 cm)氨基糖态碳含量的变化特征进行了分析。结果表明,与传统耕作相比,实施免耕7年后整个耕层土壤中氨基糖态碳含量显著增加(p<0.05),以表层(0～5 cm)增加幅度最大,高达94.7%。说明在研究地区,免耕措施有利于微生物代谢物如细胞壁物质等作为潜在的碳源逐渐积累在土壤中。免耕土壤中不同微生物来源氨基糖态碳的含量均较传统耕作有显著增加,但是变化特征有所不同,其中免耕条件下真菌来源的氨基葡萄糖的积累量较传统耕作高出1倍多,而且氨基葡萄糖与细菌来源的胞壁酸的比值(6.9～7.3)显著高于传统耕作(4.7～5.4),暗示实施免耕秸秆还田7年后土壤中真菌已逐渐转为优势群体,而真菌占优势的农田生态系统具有更大的固碳潜力。

Accumulation of amino sugar carbon affected by tillage in black soil in Northeast China

Soil tillage practices have been shown to have significant influence on microbial activity and community structure through changing soil chemical and physical properties,and as a further consequence on sequestration of soil organic carbon(C).Analysis of soil amino sugar C helps us further understand the underlying microbial processes mediating soil organic carbon stabilization and turnover in soils under different tillage practices.Effects of no-tillage(NT) vs.conventional tillage(CT) over 7 years on the accumulation of amino sugar C in the plow layer(0~20 cm) in black soil of a 7-year-long experiment in Northeast China were analyzed.It was found that NT significantly increased the content of total amino sugar C in the whole plow layer(p<0.05),especially in the top soil(0~5 cm) by 94.7% as compared with CT.The finding indicates that NT favors sequestration of microbial derived organic C in the black soils under study.The amounts of amino sugar C’s of different sources all increased in NT over CT in a varying degree.At all the three soil depths,the ratios of glucosamine to muramic acid were significantly higher in NT soils(6.9~7.3) than in their respective CT soils(4.7~5.4) mainly because of more pronounced enrichment of gulcosamine.The enrichment of fungal-derived glucosamine suggests that fungi have gradually grown into dominance in the NT agroecosystems,thus leading to higher soil organic C storage in the soils.