Effects of Long Term Application of Organic Residuals On Quantitative and Qualitative Soil Carbon Sequestration.

Application of organic residual by-products (e.g. biosolids, composts) to soil may provide an effective method for sequestering considerable amounts of carbon (C), but the long term stability of such C is not well known. We investigated the amounts and forms of C remaining in soils years following amending with biosolids and composts. Soil samples were collected in spring to summer, 2011 from agricultural and reclamation sites throughout Virginia where organic residuals had been applied either in repeated application or single large application during 1984-2010. Carbon analyses include: total organic C determined by dry combustion method, C fractions obtained by physical (i.e. size and density) and chemical (i.e. base and acid) extraction methods, and measured by solid-state ¹³C nuclear magnetic resonance (NMR) spectroscopy. Effects of soil type, sampling depth, and crop management were assessed. The expected results are that the chemistry of the organic residuals may influence the dynamics of organic C during long term periods; thus evaluating the soil C pools will be of great importance in order to elucidate the role of such residuals in sequestering C.