土壤微生物参与很多重要的生态过程，对维持农田生态系统的可持续性有重要意义。同时土壤微生物极易受到外界环境的影响，土壤理化性质的变化将引起土壤微生物生物量、群落结构及活性等的快速响应，因此可作为衡量土壤质量变化的重要指标。东北黑土具有较高的有机碳和土地生产力，然而长期的不合理耕作导致土壤有机碳损失以及土壤结构破坏。以减少耕作强度并增加秸秆还田为主要管理方式的保护性耕作被认为是缓解土壤退化的有效措施。目前对于耕作方式影响东北黑土的研究主要集中在土壤物理化学过程上，对不同土层下土壤生态性质的时间变化研究较少。为此，中国科学院东北地理与农业生态研究所黑土有机碳与保护性耕作学科组博士孙冰洁和研究员张晓平应用磷脂脂肪酸技术结合主响应曲线分析方法对免耕、垄作和秋翻下的土壤微生物量碳和群落结构进行了动态研究，结果发现在表层0-5 cm处微生物量碳、群落丰富度及群落结构随可利用性基质的季节波动发生显著的季节变化。长期免耕和垄作有利于表层土壤微生物性质的改善，造成表层0-5 cm处较高的微生物群落总量以及真菌和细菌的生物量，但是并没有形成真菌为优势种群的群落结构。该研究成果为东北地区保护性耕作的应用推广及农田生态系统的可持续发展提供了理论依据，推动了保护性耕作其他领域研究的进一步深入。

相关研究成果发表在土壤学国际学术期刊《土壤与耕作研究》（Soil and Tillage Research）上，该研究由国家自然科学基金（41101241, 41401272, 41201217, 31170483）和中科院黑土区农业生态重点实验室课题（2012ZKHT-02）资助完成。（来源：中国科学院东北地理与农业生态研究所）

Tillage, seasonal and depths effects on soil microbial properties in black soil of Northeast China

Abstract  Tillage practice can alter the content and distribution of soil organic matter by burying crop residue and soil disturbance, which would impact soil microbial properties. The objective of the present study was to evaluate the effects of tillage practices (no tillage, NT; ridge tillage, RT; mouldboard plow, MP) and sampling date (April, June, September) on soil microbial properties at different soil depths. Soil core samples were taken at 0–5, 5–10 and 10–20 cm depths from a long-term tillage experiment site (initiated in 2001) in black soils in northeast China. Microbial biomass and extractable organic C were determined using by chloroform-fumigation-extraction method. Microbial abundance and community structure were determined using the phospholipid fatty acid (PLFA) method. Principal response curve (PRC) analysis revealed the magnitude of the effect of sampling date on the PLFA relative abundance decreased with depth within the tilled layer, whereas increased with depth for tillage practice. Microbial biomass carbon, abundance and the F/B ratio varied with the variation in available substrates at the 0–5 cm depths. NT and RT improved microbial abundance (total, fungal and bacterial abundance) in the 0–5 cm depth soil, but they did not contribute to a higher F/B ratio in the 0–5 cm depth soil, and had a lower F/B ratio than MP in the deeper soils below 5 cm depth. These results demonstrated that long-term conservation tillage practice has potential for improving microbial properties in surface soil, but may not cause a shift of microbial community structure in Northeast China.

原文链接：http://www.sciencedirect.com/science/article/pii/S0167198715300313