Author
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Reicosky, Donald |
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Submitted to: National Conservation Tillage Digest
Publication Type: Trade Journal Publication Acceptance Date: 7/5/1996 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Soil carbon management is vital for agricultural production because of the importance of carbon in maintaining fertility, physical properties and biological activity. Minimizing agriculture's impact on the global increase of CO2 requires that we sequester carbon through improved residue and tillage management. The impact of long-term tillage and crop rotations son carbon loss from the soils was reviewed. The CO2 fluxes after four tillage methods that included moldboard plow, moldboard plow plus disk harrow, disk harrow and chisel plow using standard tillage equipment following a wheat crop were compared with no-tillage. The CO2 flux was measured with a large portable chamber system commonly used to measure crop canopy gas exchange. Agriculture and intensive tillage has caused between 30 and 50% decrease in soil carbon since the soils were brought into cultivation. Short-term CO2 evolution immediately after tillage showed CO2 loss after moldboard plowing was larger than that from any other tillage method. The initial CO2 fluxes were large and showed a rapid decline within the first hour after plowing. Moldboard plowing appears to have two major effects, one to loosen and invert the soil to allow rapid CO2 loss and O2 entry, and secondly, to incorporate and mix residues for enhanced microbial attack. Moldboard plowing perturbs the soil system and causes a shift in the gaseous equilibrium by releasing the CO2 and enabling O2 to enter the soil. Improved management of the soil through improved methods of conservation tillage or forms of no-till will enable the soil organic matter to be sustained in agricultural systems. Management decisions that influence intensive tillage and the amount and placement of residues will have a significant effect on the soil carbon. |
