Soil structural characteristics affected by grassland management and land use along a soil texture gradient in North Carolina

Soil structure is an important feature that facilitates water infiltration, storage, and transport into the profile, as well as affecting soil organic matter storage, habitat for soil organisms, and nutrient cycling. How land use and grassland management affect soil structural characteristics in the warm, humid region of the southeastern US remains poorly described. A cross‐sectional study from 308 grassland fields and 29 woodlots was sampled at 0‐ to 10‐cm depth in North Carolina. Soils were mostly Ultisols (90%) and included some Alfisols, Inceptisols, and Entisols. Soil texture classes included sand (6%), loamy sand (7%), sandy loam (21%), sandy clay loam (27%), loam (17%), clay loam (13%), silt loam (7%), and silty clay loam (1%). Overall, soil bulk density was greater under grassland than under woodland (1.26 vs. 1.06 Mg m −3 , respectively) but the difference narrowed with finer soil texture. Mean‐weight diameter of water‐stable aggregation was greater under grassland than under woodland in fine‐textured soils but not in other soils. Soil stability index was not different between grassland and woodland, possibly due to high levels (>90%) in both land uses. Several grassland management factors influenced soil structural characteristics, including prior land‐use history, pasture age, stocking density, and forage utilization. Soil structural characteristics were strongly negatively associated with sand concentration and positively associated with soil‐test biological activity. Older pastures with moderate grazing pressure exhibited the strongest soil structural characteristics on medium‐ and fine‐textured soils, thereby delivering vital ecosystem services from this widely prevalent land use in the eastern United States.