| چکیده انگلیسی مقاله |
Soil quality is the capacity of a soil to function within ecosystem and land use boundaries to sustain biological productivity, maintain environmental quality and promote plant and animal health. The usefulness of the soil quality concept can be enhanced greatly by making it objective, quantitative and precise through development of appropriate soil quality indices. Key soil properties can be used as indicators of sustainable soil management. The standard or reference values should be established for specific kind of soils or group of soils that function similarly and for specific land uses based on best management practices. Then assessment of soil quality can be made by comparing the measured value of an indicator with its reference value. Soil erosion affects soil quality through its effects on inherent soil properties like rooting / topsoil depth, available nutrient content and soil clay content and on efficiency of use of external inputs like fertilizer, irrigation and tillage energy. Determinants of soil physical quality are adversely affected by soil erosion. The most reactive portion of the soil are the organic and clay fractions. Accelerated erosion is a selectively destructive process because it removes one of these key reactive fractions of soil which leads to degradation in soil physical properties. Soil structure is an important attribute of soil physical quality, and its maintenance and improvement are essential for reducing soil erosion risks. Soil erosion rate is determined by the quality of soil aggregates to withstand the forces of raindrop impact and surface flow. Soil aggregation decreases with increasing severity of erosion. Soil organic carbon level needs to be maintained or increased because of its strong impact on aggregation and soil quality. The magnitude of erosion and, therefore, its effect on soil quality vary with land use. As the intensity of land use increases, the amount of ground cover and associated root contribution decreases, the quantity and quality of soil organic carbon decreases, and soil quality is reduced. So, it can be concluded that soil quality and soil erosion are tightly interrelated phenomenon. Soil quality affects the rate of soil erosion and is in turn affected by it. |
