The subsequent study aimed to determine the humus stock variations with diverse utilization of arable gray-brown soils in the arid subtropical zone. Based on the results, significant variations were prominent in humus stocks of gray-brown soils with diverse arable land uses under arid subtropical conditions. Climate change also considerably contributes to intensification of this process. Field and laboratory analyses revealed that the humus content in the topsoil ranges between 2.13% and 2.48%. The recording of lower humus levels appeared with cotton and maize crops, whereas relatively higher values were evident with alfalfa and winter wheat. The highest increase in humus content surfaced under alfalfa (0.26%), while the lowest increase was in the maize crop (0.05%). The input of plant residues varied, reaching 94 t/ha under alfalfa and 3.59 t/ha under vegetable crops (tomatoes). Over the last 15 years, mineralized humus under alfalfa reached 1.60 t/ha, while the lowest value (1.05 t/ha) emerged under vegetable crops. In the 0–30 cm soil layer, the humus stock balance was 28.58% for alfalfa and 2.60% for silage maize. Overall, a positive balance was notable with alfalfa, winter wheat, and grain maize, whereas a negative balance occurred for silage maize, cotton, and vegetable crops.

Keywords: Arid subtropics, gray-brown soils, humus loss, mineralization, humus balance

Key findings: Crop type was distinctively the main factor in the management of humus dynamics, with perennial crops (alfalfa and grasses) enhancing humus accumulation, while intensive crops (cotton, maize, and vegetables) contributed to its depletion. Overall, sustainable humus management requires the inclusion of perennial crops for improved residue return to the soil.