Submitted to: American Society of Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: July 22, 2003
Publication Date: November 2, 2003
Citation: COCHRAN, R.L., COLLINS, H.P., GRUNWALD, N.J., KENNEDY, A.C. SOIL MICROBIAL RESPONSES TO CONVERSION OF NATIVE SHRUB-STEPPE ECOSYSTEM TO IRRIGATED AGROECOSYSTEM. AMERICAN SOCIETY OF AGRONOMY ABSTRACTS - CD-SO3, Cochran 697377. 2003. Technical Abstract: Soil disturbance as a result of cultivation has been shown to impact the size of microbial populations, biomass, and microbial activity. Microbial community structure is influenced by soil properties and by cropping systems. There is limited knowledge of the dynamics of microbial community structure and the functional contribution of microbial communities to the soil ecosystem. The purpose of this study is to investigate the changes that occur in soil microbial populations due to the transformation of a native shrub-steppe ecosystem to an annual crop rotation. We evaluated soil samples from three native shrub-steppe sites and six cultivated sites, three fields comprising one year of cultivation and three fields comprising two years of cultivation. We measured changes in microbial biomass C and N, C and N mineralization and microbial populations on selected media. Microbial populations monitored included plant pathogens (Aphanomyces euteiches, Pythium spp., Fusarium solani) and communities of actinomycetes and pseudomonas. Populations of pseudomonas and certain plant pathogens increased during transition from native to cultivated soil.