A soil test utilizes an extractant to determine the amount of plant nutrients in the soil. A soil extractant is a solution made up of water and a certain concentration of chemicals. The extractant is added to a fixed amount of soil and the two are sh aken together for a prescribed length of time. The mixture is then poured through a filter paper. The soil is retained on the filter paper and the extractant, now containing the dissolved plant nutrients, is caught in a vial. The plant nutrients in the extractant are then analyzed using the appropriate laboratory instruments to see how much was removed from the soil. The amount of the nutrients extracted will represent a fraction of the total nutrients available to the plants throughout the growing se ason. Calibration data from previous field experiments serve as a guide in rating the amount of extractable nutrients as low, medium or high. These ratings are then used to determine the amount and type of fertilizer, e.g., phosphorus (P2O5) and potash (K2O), needed for optimum crop production. Note: Soil testing for nitrogen is a special situation which is not included as a routine test in all the Southeastern states due to the mobile nature of nitrate-nitrogen.