Long-Term Dryland Organic Rotations Impact Soil Health and Soil Microbial Community in Eastern Washington.

The Boyd Farm project was established in eastern Washington as a dryland organic transition study in 2002, and was continued into the certified organic production phase, where several organic cropping systems were implemented with different crop rotation and management practices. The systems were established to compare productivity, soil fertility, and soil quality outcomes that result from organic and conventional production practices. After the 2014 season, organic treatments will have been managed organically for 12 years. Differences in soil microbial community substrate utilization rates, potential enzyme activities, and community composition will be examined in three systems. System 1 is a five-year organic alfalfa (three years)/winter wheat/spring barley rotation; System 2 is an organic winter wheat/spring wheat/winter peas (hay) rotation receiving poultry manure, and System 3 a conventional winter wheat/spring wheat/winter peas (hay) rotation. Differences in total soil carbon and nitrogen have already been observed in these three systems; organic systems 1 and 2 have significantly greater total C and N than conventional system 3. It is expected that these differences in soil quality will have impacts on soil health and microbial community measures.