|Lorenz, K - THE OHIO STATE UNIV.|
|Lal, R - THE OHIO STATE UNIV.|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: October 9, 2005
Publication Date: N/A
Technical Abstract: Land use and soil management affects pools, chemical composition of stabilized C fractions and the depth distribution of total soil organic carbon (SOC). No-till production of corn (Zea mays L.) is a recommended management practice that reduces soil losses and increases SOC concentration, but knowledge of the mechanisms of C sequestration and protection is scanty. Therefore, the objective of this research was to compare the SOC pool, C pool in fine roots, and chemically identifiable C fractions in different soil horizons in four pedons: (i) secondary forest (Forest), (ii) meadow converted from no-till corn in 1988 (Meadow), (iii) continuous no-till corn since 1970 (NT); and (iv) continuous no-till corn with beef cattle manure since 1964 (NTm) at the North Appalachian Experimental Watershed near Coshocton, Ohio. The SOC pool (Mg ha-1) from 0-46 cm was greatest in NTm (69.4) and progressively lower in Forest (61.1), NT (45.2), and Meadow (42.7). The SOC concentrations and pool sharply decreased with depth, but were always greater in NTm than NT. Fine root C pool (Mg ha-1) was much larger in those pedons with perennial vegetation (Forest, 1.04; Meadow, 1.13) than in those under corn (NT, 0.15; NTm, 0.07). The pool of chemically identifiable C fractions and their depth distribution varied depending on the separation technique. The NTm pedon contained the largest amounts of stable/old C bound to soil minerals (16.1 Mg ha-1) in 0-46 cm depth, as indicated by treatment with HF to release mineral-bound SOC. This pedon also had a larger pool of recalcitrant non-hydrolyzable C (53.4 Mg ha-1), as indicated by HCl treatment. In contrast, the Forest stored the largest pool (10.6 Mg ha-1) of highly refractory, most probably slowly cycling C, as indicated by treatment with disodium peroxodisulfate (Na2S2O8). Furthermore, different C fractions were probably distinguished by the chemical techniques. The Na2S2O8 treatment probably separates chemically resistant SOC fractions with higher turnover times that generally increased in proportions with depth. The relation between chemically identifiable C fractions and turnover time of SOC at depth, however, warrants further studies. In general, no-till corn with added manure has a high potential for C sequestration by increasing the size of the SOC pool in subsoil horizons.