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Taskin Oztas University of Ataturk, Faculty of Agriculture, Department of Soil Science, Erzurum, Turkey Abstract Rapid increase in human population increased the stress on natural resources including soil. Soil degradation impacts on agricultural production and adversely affect on other natural resources. It is important to define the processes, factors and causes of soil degradation, and to assess the quality of soil that indicates the capacity of soil to sustain biological productivity and promote plant and animal health, for sustainable resource management. Assessment of soil quality, therefore, is useful for evaluating the effects of different management practices on soil and, is needed for measuring changes in soil resources within a specific period. Introduction Soil degradation refers to a decline in soil's productivity through deterioration of the physical, chemical and biological soil properties (Oztas, 1997). Common degradative processes and causes are water and wind erosion, compaction, crusting, salinization, alkalization, acidification, leaching, fertility depletion, loss of organic matter, and soil pollution. Soil quality is strongly dependent on the degree of these soil degradation processes, land use and management practices. Soil quality is broadly defined as the capacity of a living soil to function, within natural or managed ecosystem boundaries, to sustain plant and animal productivity, maintain or enhance water and air quality, and promote plant and animal health (Doran, 2002). Soil quality assessment is important for measuring changes in soil properties over time that helps to define effective management strategies. Although, the definition and quantitative assessment of soil quality is complicated by the fact that it is not directly consumed by human and animals as are air and water (Doran and Parkin, 1996), it should be defined because of its importance in ecosystem and environmental quality. Quantitative Indicators for Soil Quality Soil quality indicators are physical, chemical and biological properties, processes, and characteristics that can be measured to monitor changes in soil (Muckel and Mausbach, 1996). Although there is no single soil attribute or property that can be used to estimate soil quality, a group of soil attributes or properties that are sensitive and reliable for obtaining changes in soil physical, chemical and biological properties can be used to estimate soil quality. There are different approaches and proposals that can be used to quantify soil quality. Doran and Parkin (1994) described a soil quality index that consisted of six soil quality elements; food and fiber production, erosivity, ground water quality, surface water quality, air quality and food quality. This approach can be used to provide an evaluation of soil function based on specific performance criteria for each soil quality elements. Doran and Parkin (1996) proposed a minimum data set for characterizing and monitoring soil quality. Quantitative indicators of soil quality in the proposed minimum data set includes soil attributes and properties such as; texture, soil and rooting depth, bulk density, infiltration, water retention characteristics, soil organic matter, electrical conductivity, extractable N, P, and K, microbial biomass, and soil respiration. Another descriptive approach, The Wisconsin Soil Health Scorecard developed by the University of Wisconsin's Soil Health Program, was suggested by Romig et al. (1996). In this approach soil's quality or health is assessed as a function of soil, plant, animal and water properties identified by the farmers. In the soil health scorecard there are: 24 descriptive properties related to soil including; erosion, soil depth, soil structure, soil texture, compaction, surface crust, drainage, water retention, aeration, biologic activity, organic matter, soil fertility, pH, and soil test values, 14 descriptive properties related to plants including; crop appearance, nutrient deficiency, growth rate, seed germination, yield and feed value, 3 descriptive properties related to animals; human health, animal health and wildlife, and 2 descriptive properties related to water; chemicals in groundwater and surface water. The scorecard is a field tool to determine and monitor soil quality based on field experience. It provides a high to low scoring mechanism for each soil quality indicator based on soil's behaviors. Functional assessment of soil quality and health indicator data requires integration of soil quality and soil heath indicator properties with land use, landscape, and climate characteristics. Such database provides the information needed to develop site-specific management plans for maintaining or improving soil quality and soil health (Harris et al., 1996). Briefly, the assessment of soil quality has vital importance in agricultural production and maintaining environmental quality since it is the primary indicator of sustainable management. References . Doran, J.W. 2002. Soil health and global sustainability: translating science into practice. Agriculture, Ecosystem & Environment. 88:119-127. . Doran, J.W. & Parkin, T.B. 1994. Defining and assessing soil quality. p.3-21. In J.W. Doran et al. (ed). Defining soil quality for a sustainable environment. SSSA Spec. Publ. No:35. Madison, WI. . Doran, J.W. & Parkin, T.B. 1996. Quantitative indicators of soil quality: A minimum data set. p.25-37. In J.W. Doran and A.J. Jones (ed). Meths.for Asses. Soil Quality. SSSA Spec. Publ. No:49. Madison, WI. . Harris R.F., Karlen, D.L. & Mulla, D.J. 1996. A conceptual framework for assessment and Management of Soil Quality and Health. p.61-82. In J.W. Doran and A.J. Jones (ed). Methods for Assessing Soil Quality. SSSA Spec. Publ. No:49. Madison, WI. . Muckel, G.B. & Mausbach, M.J. 1996. Soil quality information sheets. p.393-400. In J.W. Doran and A.J. Jones (ed). Methods for Assessing Soil Quality. SSSA Spec. Publ. No:49. Madison, WI. . Oztas, T.1997. Toprak Degradasyonu. Ekoloji Çevre Dergisi. 22:31-33. . Romig, D.E., Garlynd, M.J. & Harris, R.F. 1996. Farmer-based assessment of soil quality: A Soil Health Scorecard. p.39-60. In J.W. Doran and A.J. Jones (ed). Methods for Assessing Soil Quality. SSSA Spec. Publ. No:49. Madison, WI. |