USING MULTIPLE-VARIABLE INDICATOR KRIGING FOR EVALUATING SOIL QUALITY

Soil quality is the most important factor for sustaining the global biosphere. Soil quality may be defined in several different ways including productivity, sustainability, environmental quality, and effects on human nutrition. To quantify soil quality, specific soil indicators need to be measured spatially. These indicators are mainly soil properties whose values relate directly to soil quality but may also include policy, economic, or environmental considerations. Because assessing soil quality is complex, the individual soil quality indicators need to be integrated to form a soil quality index. This integration needs to be flexible enough to evaluate soil quality at spatial scales ranging from the farm to the regional level, be applicable to all types of agricultural land use, and be able to incorporate all types of soil quality information. We have developed a multiple-variable indicator ranging (MVIK) procedure that may provide a means to integrate soil quality parameters into an index to produce soil quality maps on a landscape basis. These maps would indicate the areas on a landscape that have a high probability of having good soil quality according to predetermined criteria. This procedure can provide probability maps based on any range of chosen criteria and thus is universally applicable. In addition, it allows the identification of the indicator parameter(s) responsible for zones of low soil quality, thus allowing specific management plans or land use policies to be developed.