Cochise County Master Gardeners

Soils are sampled to determine physical conditions, fertility (nutrient) status, and chemical properties that affect their suitability as plant growing media. Through a combination of field and greenhouse research, analytical methods have been developed which provide quantitative estimates of plant-available nutrients. Field research determines the optimum soil test levels for various nutrients for specific soil and crop combinations. Optimum fertilizer practices can be determined by knowing the optimum test level of each nutrient for a specific crop and soil, and by knowing how much fertilizer is required to change soil test values. Soil testing is comprised of four steps: collection of a representative soil sample (yes, there is a proper way), laboratory analysis of the soil sample (find a list of labs), interpretation of the analysis results, and management recommendations based on interpreted results.