Long-term residue management and irrigation practice effects on aggregate-derived particulate organic matter fractions in a wheat-soybean, double-crop system.
Conventional agricultural management practices, such as repeated annual tillage and crop residue burning, can lead to reductions in soil carbon (C) storage and degrade soil health. Through the use of conservation tillage and alternative residue management practices, the soil C pool can increase. The objective of this field study was to evaluate the effects of long-term agricultural management practices (i.e., residue level, residue burning, irrigation, and tillage) on soil particulate organic matter (POM) fractions and their associate C and nitrogen (N) concentrations in a wheat (Triticum aestivum)-soybean (Glycine max L. [Merr.]), double-crop production system on a silt-loam-textured, loess soil following 14 complete cropping cycles in eastern Arkansas. Averaged over irrigation and tillage, the fine POM C concentration in the burn-low- (2.59 g/kg) was 1.9 times greater (P=0.04) than in the burn-high-residue treatment combination (1.35 g/kg), while the fine POM C concentration in the no-burn-high- and no-burn-low-residue combination were intermediate and did not differ (2.56 and 2.43 g/kg, respectively). The fine POM N concentration, averaged over irrigation and tillage treatments, was 1.9 times greater (P=0.02) in the burn-low- (0.21 g/kg) than the burn-high-residue combination (0.11 g/kg), while the fine POM N concentration in the no-burn-high- and no-burn-low-residue combinations did not differ (0.21 and 0.23 g/kg; respectively). Sustainable management practices in a wheat-soybean, double-crop production system in eastern Arkansas, such as no-tillage (NT) and non-burning of crop residues, compared to the traditional practices of conventional tillage (CT) following residue burning, provide alternative management practices that can potentially reduce the dependency on external inputs, including irrigation and nutrient inputs.