2008 Annual Report 1a.Objectives (from AD-416) The objective of this cooperative research project is to investigate soil microbial diversity and community structure in dryland ecosystems. 1b.Approach (from AD-416) In consultation with WSU scientists, soil microbial diversity indices and community structure patterns will be developed, and field and laboratory experiments will be designed and conducted in order to test hypotheses and determine parameters for this research. Consultation with and review by other researchers and users will ensure the research meet the specified needs. Results of this research will be jointly reported in the scientific literature and in outreach efforts to growers and field personnel. Documents SCA w/ WSU.Formerly 5348-11120-002-02S (5/06) & 5438-11120-003-02S (1/08). 3.Progress Report The objective of this cooperative research project is to investigate soil microbial diversity and community structure in dryland ecosystems. ARS scientists in the LMWC Unit at Pullman, WA in collaboration with Washington State University scientists assess soil parameters in dryland agriculture. Soil quality analyses were correlated with soil management practices that were considered erosive and degradative (disturbance, burning, continuous cropping) and those that build or maintain soil quality (Direct seed, surface residue maintenance, 3 or 4 yr cropping system). Microbial community, soil quality organic carbon and aggregate size change with management (tillage, cropping systems, organic systems). Studies of the effect of undercutting and surface disturbance on soil quality are also being studied. Microbial communities determined by phospholipid fatty acid methyl ester and substrate utilization analyses differed between no-till and traditional tillage systems. Although the change was slow, no-till soil microbial community and soil organic carbon were approaching that found in native undisturbed sites. Results show long-term cumulative benefits of no-till vs. traditional tillage on soil quality. Progress is reviewed at monthly meetings with the cooperator and staff.