Relationships of Potato Yields and Quality to Soil Test Values and Fertilizer Applications

The use of soil tests to accurately predict nutrient needs is dependent on (1) having a soil test procedure that accurately predicts when a nutrient is lacking, and (2) on the calibration of that soil test. Potatoes were grown at 17 sites in the Red River Valley over a 5-year period to determine the influence of N-P-K fertilizer on yield at various soil test levels