2006 Annual Report 4d.Progress report. This report serves to document research conducted under a specific cooperative agreement between ARS and Washington State University titled Soil Microbial Diversity and Community Structure in Dryland Ecosystems. Additional details of research can be found in the report for the parent project number 5348-11120-003-00D titled Enhancing Sustainability of PNW Agroecosystems Through Conservation Cropping Systems. The objective of this cooperative research project is to investigate soil microbial diversity and community structure in dryland ecosystems. Microbial communities determined by phospholipid fatty acid methyl ester analysis differed between no-till compared to traditional tillage systems. Many growers in the steeply-sloped Palouse region of eastern Washington and northern Idaho practice no-till; however, beneficial changes in soil parameters occur slowly. ARS scientists in the LMWC Unit at Pullman, WA in collaboration with Washington State University scientists assessed soil parameters in dryland agriculture. Results show long-term cumulative benefits of no-till vs. traditional tillage on soil quality; this information will provide growers and scientists with practical advice to aid in the development of management practices and agricultural policy. NP 202 Soil Biology: Problem Area 1: Understanding and Managing Soil Biology and Rhizosphere Ecology.