Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 3, 1996
Publication Date: N/A
Technical Abstract: Soils of the southern Great Plains are low in organic carbon (OC) and structural stability. We need an improved understanding of tillage effects on C fluxes to promote sequestration. Short-term CO2 fluxes following wheat harvest were determined in the 11th year of a tillage method study. Treatments were plowing (MT) and no-till (NT) with two crop residue levels. .Fumigation measurements, adenosine triphosphate (ATP), and OC concentrations of the 0 to 0.20-m depth were determined during the summer fallow. Without and with residues, flux densities ranged from 2.9 (+/- 0.46) to 4.1 (+/-1.04) g m**-2 d**-1 in MT soils and 1.4 (+/-0.07) to 1.3 (+/-0.47) g m**-2 d**-1 in NT soils. The high flux densities persisted for 3 days after plowing then declined to a basal rate of 0.4 g m**-2 d**-1. CO2 pulses coincided with accumulations of microbial ATP. Water content was a controlling factor as high fluxes were related to soil wetting and drying, primarily in the 0 - 0.05-m depth. Crop residues and tillage method affected the intensity of C fluxes and mineralization, suggesting that soil management practices can be developed to reduce C loss and associated degradation in soil quality.