Soil-profile fertility is altered by soil texture and land use across physiographic regions in the southeastern United States

Abstract

Soil fertility is often considered solely a function of soil chemical properties but should also encompass aspects of soil physical and biological properties and processes. Statistical distributions of soil properties are not readily available within the southeastern United States but could help target management interventions within common land uses. We determined soil fertility characteristics at 0- to 10-cm, 10- to 30-cm, and 30- to 60-cm depths across a combination of 56 research stations and private farms (n = 614 soil profiles) in coastal, piedmont, and mountain physiographic regions of North Carolina and Virginia. The inherent soil characteristic of sand concentration varied greatly within and among physiographic regions and was a key determinant of soil chemical characteristics, such as cation exchange capacity, soil pH, and base saturation. However, the management factor of land use was also highly influential for many soil properties. On average, soil under no-till compared with conventional-till cropland had 15% greater cation exchange capacity, 27% greater Mehlich-3-extractable Ca, 68% greater soil stability index, and 63% greater soil-test biological activity at 0- to 10-cm depth. There were fewer differences deeper in the profile. Soil under grassland compared with no-till cropland had 39 ± 6% greater extractable potassium (K) throughout the soil profile and 22% greater soil stability index, 68% greater soil-test biological activity, and 8% lower bulk density at 0- to 10-cm depth. Statistical distributions of chemical, physical, and biological properties across a diversity of soil textural conditions and land uses offered a first step toward regional assessments that could be associated with nutrient sufficiency levels and targeted management interventions.