University of Tehran Press Iranian Journal of Soil and Water Research 2008-479X 56 7 2025 09 23 Assessment of the Effects of Water Erosion on Changes in Soil Physical, Chemical, and Biological Properties in the Monzelab Watershed, Zahedan County Assessment of the Effects of Water Erosion on Changes in Soil Physical, Chemical, and Biological Properties in the Monzelab Watershed, Zahedan County 1781 1798 104184 10.22059/ijswr.2025.395713.669946 FA Morteza Saberi Rangeland and Watershed Management Department, Faculty of Water and Soil, University of Zabol Mohammad Reza Dahmardeh Ghaleno Rangeland and Watershed Management Department, Faculty of Water and Soil, University of Zabol, Zabol, Iran Rasool Khatibi Rangeland and Watershed Management Department, Faculty of Water and Soil, University of Zabol. Zabol, Iran Vahid Karimian Nature Engineering of Department, Faculty of Natural Resources, Yasouj University, Yasouj, Iran. Journal Article 2025 05 21 The present study investigated the effect of water erosion on changes in the soil's physical, chemical, and biological properties in the Manzlab watershed as a study unit. We conducted soil sampling (0-30 cm depth)  in four conditions: no erosion, low erosion, moderate erosion, and severe erosion in plots with specific dimensions. The physical and chemical characteristics of the soil were measured, including soil texture, bulk density, porosity, soil moisture content, acidity, electrical conductivity, lime, organic carbon, total nitrogen, available phosphorus, and potassium to evaluate the overall soil performance. Soil biological indicators were measured, including soil enzymatic activity, microbial biomass carbon and nitrogen, microorganism population, soil microbial contribution, and basal microbial respiration. Data analysis was done using a one-way analysis of variance with three replications using SPSS software. The findings from the variance analysis showed that erosion intensity affects all physical, chemical, and biological properties of the soil significantly. With increasing erosion intensity, total carbon, nitrogen, potassium, phosphorus, and soil porosity decreased. Unlike nutrients, acidity, electrical conductivity, and lime and soil bulk density increased significantly with increasing erosion intensity. The results showed that erosion intensity affects all biological indicators significantly. Erosion intensity had a significant decreasing trend on all biological parameters, which indicates a decrease in biological quality and disruption in soil microbial activity. Generally, changes in soil microbiota characteristics are strongly related to erosion-induced changes in soil physicochemical properties. Therefore, the utility of effective conservation and management measures is advocated to prevent further degradation in erosion-affected areas. The present study investigated the effect of water erosion on changes in the soil's physical, chemical, and biological properties in the Manzlab watershed as a study unit. We conducted soil sampling (0-30 cm depth)  in four conditions: no erosion, low erosion, moderate erosion, and severe erosion in plots with specific dimensions. The physical and chemical characteristics of the soil were measured, including soil texture, bulk density, porosity, soil moisture content, acidity, electrical conductivity, lime, organic carbon, total nitrogen, available phosphorus, and potassium to evaluate the overall soil performance. Soil biological indicators were measured, including soil enzymatic activity, microbial biomass carbon and nitrogen, microorganism population, soil microbial contribution, and basal microbial respiration. Data analysis was done using a one-way analysis of variance with three replications using SPSS software. The findings from the variance analysis showed that erosion intensity affects all physical, chemical, and biological properties of the soil significantly. With increasing erosion intensity, total carbon, nitrogen, potassium, phosphorus, and soil porosity decreased. Unlike nutrients, acidity, electrical conductivity, and lime and soil bulk density increased significantly with increasing erosion intensity. The results showed that erosion intensity affects all biological indicators significantly. Erosion intensity had a significant decreasing trend on all biological parameters, which indicates a decrease in biological quality and disruption in soil microbial activity. Generally, changes in soil microbiota characteristics are strongly related to erosion-induced changes in soil physicochemical properties. Therefore, the utility of effective conservation and management measures is advocated to prevent further degradation in erosion-affected areas. https://ijswr.ut.ac.ir/article_104184_a30bd1603d93bbc5801225e28b5987b2.pdf