Changing soil characteristics as affected by different land uses in a humid region, west of Iran

Land use change, mostly from forest to conventional agriculture, has a detrimental impact on soil health and production. However, the impact of such LUC on soil biological characteristics is unknown. This study aimed to evaluate some of the physicochemical and biological properties of soil with varied land uses in the southwestern Khorramabad area. The research locations comprised diverse land use types including coniferous forest, broadleaf forest, farmland, and rangeland. According to the findings, there was no significant variation in bulk density (ρb) and bulk density at 33 kPa (ρb33) for various land uses, but there was a significant difference between different soil layers. The amount of clay and silt varies dramatically across land uses. However, the quantity of sand used did not differ significantly across the usage (p <0.05). The results showed that the highest and lowest values of soil pH were observed in the coniferous forest and rangeland, respectively. Although the EC in coniferous forests was greater (0.17 dS m-1) than in other land uses, there was no significant difference in the average soil EC in various land uses (p <0.01). In terms of soil organic carbon (SOC), the greatest value was found in broadleaf forests with an average of 1.517 (ton/ha), while the lowest content was observed in farmland with an average of 0.797 (ton/ha). The findings showed that there is a significant difference in soil nitrogen averages across different land uses followed by the decreasing order of broadleaf forest (0.11%)> rangeland (0.06%)> Farmland (0.05%)> coniferous forest (0.03%). The findings also suggested that the quantity of microbial respiration has considerably declined in all locations as land use has shifted from forest to pasture and farmland. Notably, farmland includes the greatest population of fungi, bacteria, and actinomycetes, with a significant difference from other uses (p <0.01). Additionally, the relationship between OC and other soil factors is the most significant in this study.