Monday, November 5, 2007
98-3
Soil Aggregation and Carbon Sequestration as affected by Long-Term Tillage Practices.
Maysoon M. Mikha, Joseph G. Benjamin, and Merle F. Vigil. USDA, USDA-ARS, 40335 County Road GG, Akron, CO 80720
In agricultural systems, soil structure is an important property that mediates many soil physical and biological processes and controls soil organic carbon (SOC) content. Cultivation affects soil structure due to the destruction of soil aggregates the lost of SOC. Different management practices, such as tillage practices can effect the formation and the stabilization of soil aggregate through changes in SOC levels and soil microclimate. Our study evaluated selected soil properties related to soil quality in research plots established in 1986 on a Weld loam (fine, smectitic, mesic aridic Paleustolls). Winter Wheat-Fallow (W-F) with various tillage practices (no-tillage, NT; conventional tillage, CT; reduce tillage, RT; and plow, P) were evaluated. We investigated the effects of different tillage practices on soil organic C, aggregate-size distribution, and particulate organic matter (POM). Soil samples were fractionated into two groups of aggregate size: macroaggregates (>250 mm) and microaggregates (< 250 mm) by wet sieving. Relative to plow treatment, NT and RT significantly increased SOC, soil macroaggregates, and POM. For this soil, twenty years of NT and RT have a positive effect on soil structural stability and soil C storage.