تحلیل پیامدهای فرسایش بادی بر ویژگی‌های شیمیایی و میکروبی خاک در اکوسیستم خشک (مطالعه موردی: ایرانشهر، استان سیستان و بلوچستان)

Soil degradation is closely linked to increased wind erosion. Wind erosion is a worldwide environmental issue, especially in arid and semi-arid ecosystems where soils have low cohesion, unstable structures, and sparse vegetation cover. Besides its widespread effects on climate, air quality, and human health, wind erosion can displace and destroy fine organic particles on the soil surface. This process leads to a significant loss of nutrients, decreased fertility, and the breakdown of the soil’s physical and biological structure. Given the arid climate of the Iranshahr region in Sistan and Baluchestan Province and the strong winds that exacerbate wind erosion, examining this phenomenon's impact on soil properties is particularly important. Therefore, this study aims to explore how wind erosion affects the physical, chemical, and microbial properties of soil in Iranshahr's dry ecosystem.
Materials and Methods
In this study, to examine the effect of wind erosion on soil property changes, sampling was conducted in the Iranshahr region using a completely randomized design. The soil erosion intensity was categorized into four levels: no erosion, low, moderate, and severe erosion. In each erosion category, four homogeneous areas with similar physiographic conditions were selected, and five soil samples were collected from a depth of 0 to 30 cm in each area. The samples were combined using a composite method and, immediately after collection, transferred to the laboratory in closed containers to analyze biological properties, maintaining initial humidity and storing them in a refrigerator. The remaining samples were prepared by air drying, passing through a 2 mm sieve, and used to determine physical and chemical properties. Physical properties measured included soil texture, bulk density, and porosity. Chemical properties such as organic carbon, total nitrogen, available phosphorus and potassium, pH, and electrical conductivity were also analyzed. Soil biological properties were assessed by measuring catalase enzyme activity, basal and stimulated microbial respiration, microbial biomass carbon and nitrogen, and calculating microbial contribution. Data analysis was performed using one-way analysis of variance (ANOVA) in SPSS version 26, with means compared through Duncan's test at the 95% confidence level. Additionally, correlations between the studied properties were examined using R software.
Results and Discussion
The results of the present study showed that the intensity of wind erosion significantly affects the physical, chemical, and microbial properties of the soil. Data analysis revealed that as erosion intensity increased, organic carbon and total nitrogen decreased significantly. Soil organic carbon decreased from 0.59% in non-eroded areas to 0.16% and total nitrogen decreased from 0.063 to 0.016% in severely eroded areas. Additionally, available potassium and phosphorus were highly sensitive to erosion, decreasing from 161.3 to 79 mg/kg and from 8.32 mg/kg to 3.45 mg/kg, respectively, likely due to the wind-driven displacement of nutrient-rich fine particles. Electrical conductivity increased with erosion intensity, whereas bulk density rose and porosity decreased, indicating greater soil compaction and destruction of soil aggregate structure. Soil acidity did not differ significantly across erosion levels. Microbial indices were also adversely affected by erosion. Catalase enzyme activity, basal and stimulated microbial respiration, biomass nitrogen, and microbial population all showed significant declines with increasing erosion severity, reflecting limited food resources and reduced microbial metabolic activity. However, the ratio of carbon to biomass nitrogen and the soil microbial contribution remained relatively stable, suggesting that some microbial processes persist even under severe erosion conditions. These findings indicate that wind erosion not only diminishes the quality and quantity of soil nutrients and organic matter but also severely disrupts soil structure and microbial activity. These indices can serve as effective criteria for assessing the impact of wind erosion in arid ecosystems, particularly in Iranshahr. Correlation analysis revealed that soil erosion has a significant negative mpact on the relationships between soil erosion and microbial traits. Catalase enzyme activity, microbial respiration, carbon and nitrogen biomass, and microbial population were all strongly negatively correlated with erosion intensity. Biological indicators function interdependently, with the carbon-to-nitrogen ratio of biomass showing a strong positive correlation with microbial contribution. These results confirm the weakening of microbial network function under erosion.
Conclusion and recommendations
The results of the study in Iranshahr demonstrate that wind erosion significantly impacts the physical, chemical, and microbial properties of soils in arid ecosystems. The intensity of erosion causes the soil to become lighter, reduces porosity and water-holding capacity, destroys soil structure, and diminishes microbial activity. The decline in available carbon, nitrogen, potassium, and phosphorus, along with an increase in electrical conductivity, places stress on microbial communities, although microbial contributions to organic carbon are maintained to some extent. These findings underscore the importance of comprehensive soil management and vegetation protection, suggesting that soil stabilization, reduction of overgrazing, minimized tillage, and increased organic matter can help maintain the structure and function of dryland ecosystems.