Land management effects on wet aggregate stability and carbon content

Land management affects soil structure and many other properties processes. Our objectives were to evaluate organic C (SOC), aggregate size distribution, aggregate-associated C, as affected by long-term land slope. A chronosequence of 38 on-farm sites with low high (5–18%) slopes was selected 5–40 yr management. The classified business usual (BAU) cropland (BAU-Crop), BAU pasture (BAU-Past), newly established conservation reserve program (CRP) areas (CRP-New), CRP (CRP-Old). Soil samples collected from the 0-to-5- 5-to-15-cm depth increments processed for property measurements including fractionation wet sieving into five classes (>2,000, 1,000–2,000, 500–1,000, 250–500, 53–250 ?m). Within surface 5 cm, mean weight diameter (MWD) geometric (GMD) used characterize structural stability. BAU-Past CRP-Old had 79% more macroaggregates 500–1,000 ?m), 123% higher MWD, 38% GMD, 47% SOC than BAU-Crop or CRP-New sites. increment showed a similar but lower magnitude response. Aggregate-associated quantified using constant mass that reflected distribution prevent overestimating content. Lower-slope locations SOC, macroaggregates, associated GMD MWD compared high-slope across all classifications depths. results support our hypothesis high-slop soils may benefits specific decisions lower-sloping function landscape property. We recommend reestablishing grassland on sloping is susceptible excessive erosion, although those practices will likely take long time restore stability content precultivation levels.