Effects of Compost Tea On Soil Microbial Biomass Carbon, Nitrogen, and Phosphorus.

Compost teas are applied to soils in an attempt to increase productivity, improve soil quality, and suppress disease.  Compost teas are concentrated solutions of micro-organisms and nutrients that are extracted from compost using an aerated brewing method over a 24 to 48-hour period. Preliminary experiments investigating the effects of compost tea have led to questions regarding effective tea application rates and microbial responses to compost tea applications.  In order to address these questions we have designed a multifaceted approach using the following three experiments to examine the effect of tea additions: 1) Impact of compost tea on soil microbial biomass carbon (C), nitrogen (N), and phosphorus (P); 2) Effects of compost tea additions on soil extractable nutrients; 3) Response of soil microbial respiration following additions of compost tea. In all of these studies we will test the response of a forest soil to various application rates of compost tea in temperature controlled microcosms.  For this specific experiment, we hypothesize that the rate of compost tea addition will be positively and linearly related to microbial biomass C, N, and P. Data from this experiment will provide much needed information regarding how tea additions impact microbial communities without competing forces such as plant assimilation. With this knowledge we will be more equipped to apply our objectives at a field scale and conduct in situ experiments.