Microbial community structure in long-term no-till and intensive-till soils

Abstract

Conversion from intensive tillage (IT) to no-till (NT) management creates an altered habitat for soil microorganisms. We utilized four long-term tillage experiments in Saskatchewan and Alberta to compare NT and IT microbial communities. Microbial abundance increased at the soil surface (0- to 5-cm depth) in NT vs. IT soils. Differences were much less pronounced or negligible at the 5- to 10-cm and 10- to 15-cm depths. Despite increased biomass of fungi and bacteria in NT surface soils no significant shift in the relative proportion of individual groups of organisms within the community was observed. Similarly, analysis of bacterial DNA fingerprints indicated that while microbial community clusters in the 0- to 5-cm depth increment were different than those at greater depth, there was no significant effect of tillage. Our results demonstrate that depth was a stronger determinant of microbial community structure than tillage management.