Role of Biological Oxidation and Organic Matter Solubilization in the Subsidence of Rifle Peat 1

Natural profile columns of Rifle peat were obtained by driving asphalt coated steel cylinders into the soil. The columns were incubated in the laboratory for a 102-day preamendment period. Carbon-14 labelled rye tissue was then mixed with the upper 6 inches of the soil profile and the columns were incubated for an additional 107 days. Irrigation water was applied and CO₂ evolution and organic matter in the drainage water were determined throughout the incubation period. The pattern of CO₂ evolution and carbon balance relationships were considerably different from that obtained when small samples of disturbed, air-dried peat were incubated with plant tissue. There was no evidence of “priming action” due to the addition of tissue, but considerable amounts of organic matter were lost in the drainage water. The addition of plant tissue reduced the rate of biological oxidation of Rifle peat. Tile systems should be placed below a horizon which adsorbs water-soluble organic matter if loss of organic matter in drainage water is to be controlled.