Soil mean-weight diameter and stability index under contrasting tillage systems for cotton production in North Carolina

Abstract

Coarse-textured soils are typically not highly aggregated due to low surface reactivity of sand-sized grains. However, soil erosion and surface sealing can still be a concern from frequently tilled soil in relatively flat landscapes of the Coastal Plain and Flatwoods of the southeastern United States. Soil at 0-to-10-cm depth was sampled from 120 randomly chosen cotton (Gossypium hirsutum L.) fields in North Carolina, which could be separated into three categories of tillage system: frequent disk tillage, rotated conservation and disk tillage, and continuous conservation tillage. This study assessed soil stability index derived using (a) mean-weight diameter (MWD) following water immersion and oscillation for 10 min relative to that of (b) MWD following dry sieving of soil. This whole-soil analysis had significant variation in soil stability index (interquartile range of 0.58 to 0.95 mm mm–1) along a sand concentration gradient, but that was differentiated by tillage system. The strongest association of MWD from dry-stable crumbs (r =.71, p