Submitted to: Geoderma
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/21/2006
Publication Date: 9/25/2006
Citation: Lorenz, K., Lal, R., Shipitalo, M.J. 2006. Stabilization of organic carbon in chemically separated pools in no-till and meadow soils in Northern Appalachia. Geoderma. 137:205-211. Interpretive Summary: Use of no-till management practices for crop production can reduce runoff and erosion and increase the amount of organic matter in the soil. Besides improving soil quality, this increase in soil organic matter may help to offsite the rise in atmospheric levels of carbon dioxide attributable to the burning of fossil fuels. The processes that lead to the increase in soil organic matter and how it is protected from decomposition in no-till soils, however, are poorly understood. Therefore, we compared the amounts and depth distribution of organic matter in sand, silt, and clay fractions of a no-till soil used for corn production (with and without added animal manure) to those in a meadow soil. Management practice did not alter the amount of sand, silt, and clay in the soil, but the no-till soil with added manure had more soil organic matter than the other management practices and this increase was evident throughout the entire depth of the soil. Most of this increase occurred in the silt-size fraction. Application of manure probably increased earthworm populations, which in turn probably contributed to redistribution of crop residues and increased levels of organic matter deep in the soil. These results indicate that the best way for farmers to achieve long-term increases in organic matter levels in their soils, and better soil quality, is through continued use of no-till practices, particularly if they are able to add animal manure.
Technical Abstract: Land use and soil management affects soil organic carbon (SOC) pools associated with particle-size fractions and their depth distribution. No-till production of corn (Zea mays L.) is a recommended management practice that reduces erosion and increases SOC concentration, but knowledge of the mechanisms of C sequestration and protection in particle-size fractions is fragmentary. Therefore, the objective of this research was to compare the SOC pool in coarse (0.25-2.00 mm dia.) and fine (0.05-0.25 mm dia.) organo-mineral, silt (0.002-0.050 mm dia.) and clay (<0.002 mm dia.) size fractions with depth in three pedons from the same soil series under three different long-term management practices: (i) meadow converted from no-till corn in 1988 (Meadow), (ii) continuous no-till corn since 1970 (NT); and (iii) continuous no-till corn with beef cattle manure since 1964 (NTm) at the North Appalachian Experimental Watershed near Coshocton, Ohio. Land use and soil management had no significant effects on particle size distribution with total organo-mineral particle size fraction ranging from 16 to 43%, silt fraction ranging from 38 to 58%, and clay fraction ranging from 18 to 28% of total soil mass. Land use and soil management, however, significantly affected SOC and TN pools in particle-size fractions, and their depth distribution. Clay, and particularly silt-size particles, were quantitatively most effective in sequestering SOC than the other size fractions. The SOC pool (Mg/ha) in silt-size particles from 0-69 cm was greatest in NTm (32.1) and progressively smaller in NT (19.0), and Meadow (17.9), representing 42, 39, and 38% of the total SOC pool, respectively. The SOC and TN pools in no-till with manure were greater in all particle-size fractions and in subsoil horizons compared to no-till corn without manure due to increased organic matter input and most likely by promoting earthworm activity that resulted in organic matter redistribution within the profile. Thus, manure application to no-till soils increases the potential for C sequestration by increasing the SOC pool in more stable finer particle-size fractions in subsoil horizons.