Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: July 28, 2004
Publication Date: November 1, 2004
Citation: Hansen, J. C., Kennedy, A. C., Schillinger, W. F. 2004. Organic Carbon and Microbial Community Changes in Soil Aggregates with No-till Dryland Wheat Farming. S03-hansen3955. Annual Meeting Abstracts [CD-ROM]. ASA, CSSA, and SSSA, Madison, WI. Technical Abstract: Conservation tillage or no-tillage systems are needed in the Pacific Northwest (PNW) to reduce soil erosion, maintain soil quality, enhance crop yields and improve farm profitability. The impacts of management practices on soil biotic and abiotic properties need to be considered before adoption of or changes in those practices. We investigated soil aggregation and the distribution of carbon and microbial communities in aggregates under various management systems. Soil aggregation size distribution was determined using dry sieving (1 mm, .250mm, 53 micron fractions). We investigated soil microbial communities using substrate utilization, fatty acid methyl ester and phospholipid fatty acid methyl ester analyses. Organic carbon was higher in conservation tillage systems compared to conventional systems. We found that with less disturbance, the proportion of aggregates in the larger size fractions (greater than 53 micron) increased. In conservation tillage systems, we also found that a greater percentage of the carbon was protected in the larger aggregates and thus less susceptible to loss do to erosion. Microbial communities varied with tillage and aggregate size. This information will provide growers and scientists with practical advice to help in the development of management practices that retain soil carbon and improve soil quality.