The response of certain crops to potassium on several soil types in Tennessee

Current fertilizer recommendations are frequently based on the results of soil tests carried out by rapid chemical methods. These chemical methods are designed to extract the more readily soluble and hence supposedly "available" nutrients in the soil. The amounts of such available nutrients that must be present in the soil for profitable plant growth can be determined only by actual field trials. When a sufficient body of data from both field and laboratory research has been accumulated, then fertilizer recommendations can be made safely on the basis of the chemical tests alone. For example, if a soil sample contains less than that amount of a given nutrient which field trials have shown to be necessary for proper growth of a certain crop, then fertilizer applications of that nutrient can be expected to give profitable returns.

The experimental data which form the basis for correlating quick test results with field yields have been obtained, for the most part, in regions other than Tennessee. Since regional differences in climate, soil, and farming practices are great, it is unsafe to accept quick test correlations worked out in other areas as a basis for fertilizer recommendations in Tennessee. The purpose of this study was to obtain data on quick test correlations which might contribute toward more accurate fertilizer recommendations for Tennessee conditions.

The magnitude of this task was such that one individual could deal successfully with but a small portion of the problem. Therefore, it was advisable to limit this study to a single nutrient element, potassium, and to include but a few crops on a limited number of different soil types.