Improving soil function properties in semi-arid regions using modified-chitosan and biochar.

Abstract

Understanding soil function is crucial for restoring degraded ecosystems, necessitating the evaluation of soil characteristics and processes. Soil amendments can significantly enhance various soil functions, particularly water retention, organic carbon storage, and microbial activity. However, the combined effects of these amendments on soil properties in semi-arid regions remain largely unexplored. This study investigated the impact of biochar and modified chitosan applications on the physico-chemical and microbial properties of soil at a depth of 0-20 cm in the semi-arid rangelands of Iran. The experiment included four levels of modified chitosan (0 %, 0.01 %, 0.05 %, and 0.1 %) and biochar derived from Azolla filiculoides (0 %, 0.20 %, 0.60 %, and 1.20 %), with three replications for each treatment. The percentages indicated the weight ratio of modified chitosan and biochar to the dry weight of the soil in the 20 cm surface layer. The highest doses of the two modifiers decreased bulk density by approximately 13 %, while water retention increased by around 13 % compared to the control sample. Following the application of soil conditioners, fertility indicators (C, N, P, and K) increased by factors of 2.2, 2.2, 1.4, and 5, respectively. The highest levels of urease and invertase enzymes were observed in soil samples treated with the highest dosages of modifiers, whereas untreated soil samples exhibited lower values for these characteristics. The microbial characteristics of the soil, specifically basal respiration, substrate-induced respiration, and microbial biomass carbon, showed substantial enhancement, with increases ranging from 1.5 to 2-fold in the highest dose-treated samples compared to the control. Studies evaluating the effects of soil modifiers on soil functions aim to provide a comprehensive understanding of soil dynamics. This study broadens the utilization of environmental waste and holds significant scientific importance for the development of low-cost, environmentally friendly materials. The application of these targeted methods will aid in the restoration of ecosystems in semi-arid regions.