Long-term land use effects on soil microbial community structure and function

Microbial community diversity and structure, which underpin soil function, can in turn be impacted by land-use practices. In this study an agricultural site with consistent long term (+20 years) treatments and a non-agricultural site (grassland) were investigated to determine land-use effects on soil microbial community structure and function. We used a variety of methods to investigate microbial community structure, biomass, potential and actual function and soil physicochemical properties. All soils showed similar levels of bacterial diversity although community structure (bacterial, archaeal, fungal) differed under all treatments. Overall, our results indicate that despite evident differences in microbial community structure among all soils examined, there was little functional difference among soils under cultivation in the various cropping treatments. There were, however, clear differences in both function and structure between the agricultural and non-agricultural soils. All soils were very water limited, which was reflected in negligible actual rates of nitrification, denitrification and nitrogen fixation. Non-agricultural soils showed higher rates of potential nitrification, lower rates of potential denitrification, higher levels of C and N and higher microbial biomass. These findings have implications for understanding how land-use practices affect soil microbial community structure and function and ecosystem service provision.

► Changes in land use impact soil microbial community structure, but may have less impact on soil function.
► Microbial communities differed under long term (20+ year) agricultural treatments, including conventional tillage and no-till, but function did not.
► Microbial community structure and function differed between agricultural and non-agricultural treatments and native grasslands.
► Factors other than community structure appear to play a large role in determining function.