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Title: Soil Carbon and Enzyme Activities as affected by Cropping Intensity and Tillage

item Mikha, Maysoon
item Acosta-Martinez, Veronica
item Vigil, Merle

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/8/2006
Publication Date: 1/30/2007
Citation: Mikha, M.M., Acosta Martinez, V., Vigil, M.F. 2007. Soil Carbon and Enzyme Activities as affected by Cropping Intensity and Tillage. Meeting Abstract.

Interpretive Summary:

Technical Abstract: Winter wheat-fallow (W-F) rotation is the predominant cropping system in the Central Great Plains and it is not sustainable. Alternative cropping systems with reduced tillage are being suggested to improve soil organic matter (SOM) content and other parameters related to soil quality. Our study evaluated selected soil properties related to soil quality in research plots established in 1990 on a Weld loam (fine, smectitic, mesic aridic Paleustolls). Various cropping intensities with several rotations were evaluated. We investigated the effects of cropping intensity on soil total C, aggregate-size distribution, particulate organic matter (POM), soil microbial communities, and enzymatic activities of C and N cycling. Soil samples were fractionated into two groups of aggregate size: macroaggregates (>250 micron) and microaggregates (<250 micron) by wet sieving. Continuous cropping increased soil total C, POM, and microbial biomass compared with W-F rotation. Relative to W-F conventional tillage, continuous cropping increased soil total C by an average of 0.1 ton c/a/yr to the depth of 0-6 inch. Macroaggregate was affected by tillage but not by cropping intensity. Selected enzyme activities were affected by rotation phase and fallow frequency. Fatty Acid Methyl Ester (FAME) profiles showed shifts in the microbial community structure between the alternative systems compared with W-F rotation. For this soil, fourteen years of continuous cropping and no-tillage with reduced fallow frequency have a positive effect on nutrient cycling, soil C storage, and soil biochemical functioning.