Humus Reserve Variations With Diverse Utilization of Arable Gray-Brown Soil in the Arid Subtropical Zone of Azerbaijan

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.