Ecological Indicators (Sep 2024)
Assessment of soil organic and inorganic carbon stocks in arid and semi-arid rangelands of southeastern New Mexico
Abstract
Accurately accounting for soil organic carbon stocks is crucial in assessing the sequestration potential of arid and semi-arid rangelands. This study, conducted in the rangelands near Loving, southeastern New Mexico, aims to evaluate soil organic carbon stocks, assess the potential for soil organic carbon sequestration, and identify both biotic and abiotic factors influencing this process. To achieve these goals, soil samples were collected and subjected to analysis for soil particle size, bulk density, soil characteristic curve, as well as soil total carbon and inorganic carbon. Soil total carbon stock (STCS), soil organic carbon stock (SOCS), soil inorganic carbon stock (SICS), and soil total nitrogen stock (STNS) were determined. Soil depth, vegetation types, and coverages on each ranch were identified. Additionally, soil ion concentrations, soil cation exchange capacity (CEC), and soil sodium adsorption ratio (SAR) were assessed. The soil CEC ranged from 6 to 20 meq/100 g soil, and SAR from 0.02 to 0.58 cmol/kg^0.5. The concentrations of Na and Cl were 42 and 13 mg/l, at a depth of 0–20 cm, increasing to 74 and 34 mg/l at 20–32 cm depth, respectively. In October 2021, STCS measured 39 Mg/ha at 0–20 cm and 11 Mg/ha at 20–32 cm soil depth. SOCS ranged from 18 Mg/ha at 0–20 cm to 6 Mg/ha at 20–32 cm soil depth, while SICS ranged from 20 to 1 Mg/ha at 0–20 cm and 20–32 cm soil depth, respectively. STNS varied from 1 Mg/ha at 0–20 cm to 3.8 Mg/ha at 20–32 cm soil depth. In the 20 cm sandy loam soil depth, ranches 1, 7, 8, 9, and 11 exhibited the highest SOCS, increased with increasing clay content, particularly where honey mesquite was the dominant species. These findings emphasize the importance of exploring soil carbon storage fluctuations in southern New Mexico. The differences in SOCS among ranches under different vegetation underscore the considerable potential for storing soil organic carbon in the semi-arid rangelands of this region.
