Soil profile carbon sequestration and nutrient responses varied with cover crops in irrigated forage rotations

Irrigated forage production systems are intensive and highly exhaustive on nutrients. Integration of cover crops in irrigated forage crop rotation could be a strategy to increase soil organic carbon (SOC) storage and improve nutrient cycling. However, there is a lack of comprehensive information on cover cropping strategies for improving soil health, SOC sequestration, and nutrient cycling in forage -based crop rotations in arid and semiarid environments. A four-year study (2018-2022) evaluated the effects of cover crops on soil carbon and nitrogen (N) pools and nutrient concentrations in no -tillage corn (Zea mays L.) - sorghum [Sorghum bicolor (L.) Moench] rotation. We aimed to quantify the response of SOC and N pools and other nutrients with cover cropping and elucidate their SOC sequestration potential under a forage -based crop rotation in semi -arid environments. Cover crop treatments included a mixture of grasses, brassicas, and legumes (GBL), grasses and brassicas (GB), grasses and legumes (GL), and no cover crop (NCC). Soil samples were collected from 0-80 cm profiles and measured for potentially mineralizable carbon (PMC), SOC, total labile N (TLN), inorganic N, available Phosphorus (P), Potassium (K), and other macro and micronutrients as soil health indicators. Soil PMC content under GB treatment was greater than NCC at 10-20 (85.5%) and 20-40 (70.5%) cm soil depth . The SOC was greater under GBL than under NCC at 0-60 cm (12 to 43%), while TLN was greater under GL than NCC at 0-20 cm depth (27 to 35%). The GBL mixture also enhanced soil N, P, and K within the upper 0-10 cm soil layer. The SOC stock at 0-80 cm depth under cover crops was 7-22% greater than under NCC, resulting in SOC sequestration of 1.5-2.3 Mg C ha -1 y-1 in cover crop plots. Cover cropping can increase SOC sequestration in irrigated cropping systems in semi -arid environments. Considerable increases in labile C and N components in the soil profile with cover cropping indicate long-term improvement in soil health and productivity through increased total SOC storage and improved nutrient cycling.