Empirical relationships for soil organic carbon transport from agricultural watersheds in Ohio
2008
Starr, G.C. | Lal, R. | Owens, L. | Kimble, J.
Improved quantification is needed for long-term soil organic carbon (SOC) transport in runoff at watershed scales. Coshocton wheel samplers were used to collect runoff samples from no-till and chisel-till watersheds in corn (Zea mays) and soybean (Glycine max) rotations over 13 years. Samples were analyzed for SOC, N, P, K, and soil losses. The SOC losses, ranging from 0 to 357 kg ha⁻¹ event⁻¹, were correlated (r² = 0·80-0·94) in power law relationships with N, P, K, soil loss, and runoff. Two events occurring in corn when soybean and cover crop residue were present in no-till had combined SOC transport of 460 kg ha⁻¹, nearly double the no-till losses of a previous 11-year period and 20 times higher than chisel-till in the same events. Infrequent, extreme transport events that are not well characterized empirically, particularly in no-till, can strongly influence hydrologic C transport from agriculture watersheds.
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