|DOUGLAS, JR, CLYDE|
Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 8/1/1999
Publication Date: N/A
Technical Abstract: Long-term cropping system research helps determine management effects on soil organic matter. The trends in soil C content at multiple depths in several long-term management systems on a Walla Walla silt loam near Pendleton, OR were examined and compared for C sequestration. A continuing decline of C over time was found as deep as 60 cm in systems that included burning, plowing, or fallow in the rotation. A rotation with manure applied at 2.24 Mg per ha per crop year had no decline in soil C. Soil C content was positively correlated with residue returned to the soil, which in turn was dependent upon fertility and organic amendments. Annual cropping provided improved C retention compared to fallow, and permanent pasture retained more C than any cultivated practice. Management systems that increase residue input to the soil, or decrease microbial oxidation of crop residues and soil carbon, increase the potential to sequester C in semi-arid agroecosystems.