Texture and organic matter associations with soil functional properties in crop and conservation land uses in North Carolina

Abstract

Soil texture and organic matter are considered overarching factors controlling a diversity of soil processes and properties. However, a more complete understanding of how these factors quantitatively affect other soil properties has been lacking due to either limited scope of land use and management conditions, confounding climate and environmental conditions with management, or narrow range of soil and management conditions. This study evaluated the strength of associations of sand and total soil N concentrations with soil physical, chemical, and biological properties and processes from 310 surface‐soil (0‐10‐cm depth) samples (87% Ultisols, 4% Inceptisols, and ≤3% each of Alfisols, Spodosols, Entisols, and Histosols) collected under conventional‐till and no‐till cropland, grassland, and woodland in four physiographic regions of North Carolina. Sand concentration was most strongly associated with dry‐stable mean‐weight diameter, mean‐weight diameter product, and sieved soil density (|r| > .63, p < .001). Total soil N concentration was most strongly associated with particulate organic C and N and soil water content at water‐holding capacity (|r| > .74, p < .001). Soils under unfertilized woodlands deviated the most from general associations, suggesting that organic matter quality could be unique, and requires further investigation. Overall, sand concentration associated more closely with soil physical properties and total soil N concentration associated closely with both soil physical and biogeochemical properties. Soil chemical properties were only weakly associated with either property. This study suggests that soil texture and organic matter would be complementary, additional properties in holistic soil health assessments that already included routine soil chemical analyses.This article is protected by copyright. All rights reserved

Soil aggregation and surface‐soil properties under grazed pastures and other conservation land uses in Virginia

“…Total soil N was lowest with high stocking rate, which mirrored the increase in soil bulk density at high stocking rate. Again, a strong negative association between total soil N and soil bulk density should be expected since total soil N is a direct component of soil organic matter and there is a strong negative association of organic matter with bulk density (Franzluebbers, 2024). Overall, stocking rate was not a management factor that convincingly influenced soil aggregation characteristics.…”

“…Additional supporting information can be found online in the Supporting Information section at the end of this article. Franzluebbers, A. J. (2024).…”

“…Silt was calculated from the difference between unity and summed fractions of clay and sand. Mass of soil in the 59-mL scoop of soil was used to calculate sieved soil density (Franzluebbers, 2024).…”

“…Dry-stable MWD provides an antecedent condition of soil prior to water immersion for determining aggregate stability. Dry-stable MWD is typically a function of soil texture, whereby greater clay concentration leads to greater values (Franzluebbers, 2024), depending on soil handling conditions in the laboratory (e.g., dry vs. wet sieving in the lab, screen size to homogenize samples, and aggregate selection or whole soil). Regression of water-stable MWD against dry-stable MWD indicated a close association in stability across all locations under grassland (MWD wet = −0.06 + 0.92 [MWD dry ], r 2 = 0.72, p < 0.001).…”