Soil Quality and Metagenomics Under Long Term Nitrogen Use in Illinois.

Long term fertilization can influence soil quality as well as the size, structure, and function of microbial communities present in soils yet our current knowledge and understanding of microbial responses in agroecosystems remains limited. Nitrogen fertilization trials in continuous corn CCC and corn-soybean have been in place for more than 33 years at Monmouth, Illinois, presenting a unique setting to characterize soil quality parameters, including baseline microbial composition, under long term use of typical N rates in the state. We will present preliminary data on soil quality and crop productivity which lead to our current exploration of the soil biological component of soil quality using bioinformatics and advanced statistical tools. During this presentation, we will discuss our approach to characterize shifts on the soil microbial communities and quantify genes associated with the main steps of the N cycle (biological N fixation, nitrification, and denitrification) under increasing N fertilization rates, likely related to changes in the relative dominance of each of the microbial N processes.