نوع مقاله : پژوهشی
نویسندگان
1 دانشیار دانشگاه زابل
2 استادیار گروه مهندسی طبیعت، دانشکده منابع طبیعی، دانشگاه یاسوج.
3 دانشیار گروه مرتع و آبخیزداری، دانشکده آب و خاک، دانشگاه زابل،
4 استادیار گروه مرتع و آبخیزداری، دانشکده آب و خاک، دانشگاه زابل.
5 دکتری منابع طبیعی، مقابله با بیابان زایی، دانشگاه علوم کشاورزی و منابع طبیعی گرگان، سازمان منابع طبیعی و آبخیزداری
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Introduction and Objective
Water erosion, as one of the most important factors of soil degradation, has a significant impact on soil quality and performance in various ecosystems. The Sarsaro watershed in Khash County, due to its specific climatic conditions and human interventions (such as over grazing and destruction of vegetation cover), is considered a vulnerable area to water erosion. Despite the importance of the issue, comprehensive studies simultaneously examining the physical, chemical, and biological properties of the soil in this region have not been conducted. Therefore, the main objective of this study was to evaluate the impact of water erosion on soil changes and microbial structure in the Sarsaro watershed in order to provide strategies for sustainable natural resource management through better understanding of erosion effects.
Materials and Methods
Soil sampling in this study was done in a completely randomized design. First, erosion and sedimentation maps available in the region were used to classify soil erosion intensities, including: no erosion, low erosion, moderate erosion, and severe erosion. Then, in each erosion region, four homogeneous areas with common physiographic conditions were selected. In each of them, five soil samples (one sample in the center and four samples in the form of a plus sign around it) were collected. Soil sampling was carried out from a depth of 0 to 30 cm. For each erosion site, samples collected from homogeneous areas were mixed to prepare a composite sample. Immediately after collection, the soil samples were divided into two parts. Part of the samples intended for measuring biological properties were transported to the laboratory in sealed containers to maintain the initial humidity conditions and in the vicinity of dry ice. These samples were not sieved and were stored in the refrigerator until the experiments were performed. The other part of the samples was used to measure physical and chemical properties after drying in the open air and passing through a 2 mm sieve. The data were subjected to one-way analysis of variance (ANOVA) using SPSS software. Duncan's test with a 95% confidence level was used to compare the means. Also, the correlation between the studied parameters was analyzed in the R software environment.
Results and Discussion
Analysis of variance showed that erosion intensity had a significant effect (p < 0.01) on soil physical properties. The percentage of sand increased significantly from 25% in non-eroded soils, while the percentage of silt and clay decreased respectively (negative correlation with erosion severity: -0.96 for silt and -0.95 for clay). Soil moisture in non-eroded lands was 12.5%, which decreased to 6.09% in severely eroded lands (p < 0.01). Porosity also decreased, and bulk density increased (negative correlation of -0.97 with porosity and positive correlation with bulk density). Soil chemical parameters were also affected: organic carbon decreased from 2.23% to 0.93%, total nitrogen from 0.31% to 0.08%, and available potassium and phosphorus also decreased significantly (p < 0.01), while electrical conductivity increased significantly (positive correlation of 0.92). Changes in pH were not significant (p > 0.05). Soil biological properties were severely reduced: catalase enzyme activity decreased from 28.05 units in non-eroded soils to 3.57 units in severely eroded soils (p < 0.01). Microbial biomass carbon decreased from 223.6 mg to 93.3 mg, microbial biomass nitrogen from 31.6 mg to 7.8 mg, and the population of microorganisms and basal microbial respiration also showed significant decreases (p < 0.01). The soil microbial contribution also decreased and showed a strong negative correlation (greater than -0.96) with erosion severity. These data indicate the severe negative effects of water erosion on the physical, chemical, and biological quality of the soil, as well as the reduction in its productive capacity and the ecological health of the ecosystem.
Conclusions and Recommendations
The results of this study clearly demonstrated that the intensity of water erosion has severely impacted the physical, chemical, and biological quality of soils in the Sarsaru watershed. Erosion, through the removal of surface layers, reduction of organic matter, degradation of soil structure, depletion of essential nutrients, and disruption of microbial communities, has jeopardized soil health and ecological functioning, thereby diminishing the ecosystem's productive capacity. Therefore, erosion control and integrated soil resource management should be considered critical priorities in vulnerable areas such as the Sarsaru watershed to prevent further soil degradation and loss of biological function. Biological indicators can serve as effective tools for monitoring the health of erosion-affected soils and provide a solid foundation for informed management decisions.
کلیدواژه‌ها [English]
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