Microbial Biomass Responses to Soil Drying-Rewetting and Phosphorus Leaching

Summary

Soil drying-rewetting is known to enhance soil phosphorus leaching, which in part is due to osmotic shock and lysis of microbial cells upon rewetting. However, it is not entirely clear how this may be influenced by the intensity and duration of soil drying. We hypothesized that the intensity and duration of soil drying play important roles in determining the extent of dissolved reactive phosphorus (DRP) leaching resulting from microbial biomass mortality. To test this hypothesis soil sub-samples of a loamy grassland soil were dried (30C or 40C for 2-days or 14-days), rewetted, and the leachate was analysed for DRP. Soil drying at 30C for 2-days and 14-days resulted in leachate DRP concentrations which were 71% and 271% respectively higher than those in leachate from a control moist coun