Carbon availability limits the denitrification potential of sandy loam soil from corn agroecosystems with long-term tillage and residue management

Abstract

Conservation tillage and crop residues should increase the soluble organic carbon and nitrate concentration in agricultural soil, which increases the denitrification potential. Basal denitrification (72 h laboratory incubation) was 2.1–2.7 times higher in a sandy loam soil under 15 yr of conservation tillage than conventional tillage and 1.8–2.0 times higher with high-residue (additional input 8.6–9.4 Mg dry matter·ha−1·yr−1) than low-residue inputs. Adding glucose and nitrate increased the soil denitrification potential 3- to 14-fold. Denitrification was limited by carbon availability, even in soil with 15 yr of conservation tillage and high-residue inputs.