Impact of land management and fertiliser use on soil microbial function

Abstract

Soil microorganisms are a key component for soil health and fertility as they promote the turnover of organic matter and nutrient cycling (e.g. phosphorus and nitrogen), which in turn determines plant and animal production. Assessment of soil microbial function can be achieved via various methods based on physiological processes, of which substrate-induced respiration is thought to be the most sensitive to changes in the microbial community. Therefore, MicroRespTM, a method of substrate-induced respiration, was used to assess microbial function for this study. Samples were taken from a long-term fertiliser (superphosphate) trial at Winchmore and the Long-Term Ecology Trial (LTET, biomass retetion or removal) at Lincoln University, together with a short-term dairy shed effluent trial (DSE applications) carried out at LTET. The results of this experiment showed season had a significant impact on soil microbial function, primarily due to changes in soil temperature, and to a lesser extent, soil moisture. Treatment effects of the long-term application of superphosphate and the DSE applications on microbial function were not signifcant, however, the effect of biomass retention or removal on the LTET were significant. This is primarily due to changes in soil organic carbon levels and pH which occurred under the contrasting treatments of the LTET, but not for the Winchmore and DSE treatments.