Abstract:

【Objective】 Soil microbe is an important part of terrestrial ecosystem. The objective of this paper is to elucidate the effects of different land use patterns on soil microbial biomass and community structure. 【Method】 Soil microbial biomass and community structure were analyzed by phosphdipid fatty acid (PLFA) method, based on a consecutive 19 years field trial on the aquic brown soil in Shenyang suburbs of Northeast China. There were four land use patterns included, i.e. bare land, mown land, fallow land and agricultural land. Agricultural land was comprised of CK, M, NPK and NPK+M treatments. 【Result】 The changes of bacterial and fungal PLFA were similar to total PLFAs: that of fallow and mown land were the highest and followed by arable soils, and that was the lowest under bare land. The differences of PLFAs content among the treatments in agro-ecosystems were not significant. The highest PLFA was obtained under M treatment, followed by CK and NPK+M, and that was the lowest under NPK treatment. Increasing soil microbial PLFA was contributed to land abandonment and manure application rather than mineral fertilizers application. The value of G+ PLFA/G- PLFA in natural ecosystems was higher than that in agro-ecosystems; decline of the value was due to tillage and mineral fertilizers applied. The value of bacterial PLFA/fungi PLFA of fallow and mown land were lower than that of arable soils or bare land. Correlation between soil PLFAs content and soil nutrients showed that soil microbial biomass had significant correlation with soil organic matter and total nitrogen. 【Conclusion】 Microbial biomass and community structure were influenced significantly by long-term land use patterns.

Key words: aquic brown soil, land use patterns, soil microbe, community structure, PLFA