A preliminary study on the use of rapid chemical tests as aids in diagnosing nutrient deficiencies in the Irish Potato

Abstract

1. The effects of soil applications of nitrogen, phosphorus, and potash fertilizers on the soluble nutrient content of potato leaf petioles and on yields of tubers were studied. Rapid tissue tests were used to determine the nutrient content of leaf petioles at successive intervals during the growing season. 2. Soil applications of nitrogen fertilizer at the rate of 80 pounds or 160 pounds per acre approximately doubled the N content of potato leaf petioles and doubled the yields of tubers. The concentrations of soluble P and K2O were found to be inversely correlated with the soluble N content of potato leaf petioles. 3. Soil applications of phosphate fertilizer had no effect on yields of tubers, nor on soluble N content of potato leaf petioles. Under conditions of high N supply, application of phosphate fertilier resulted in significantly higher P content and in slightly lower soluble K2O content of leaf petiole tissues. 4. Soil applications of potash fertilizer had no effect on yields of tubers nor on the soluble N content of potato leaf petioles. Under conditions of high N supply, application of potash fertilizer resulted in significantly higher soluble K2O content but had no effect on soluble P content of leaf petiole tissues. 5. Under the conditions of this experiment, the maximum yields were obtained when the soluble N content of the leaf petioles at the time of first visible flower buds were 600–700 p.p.m.; the soluble P content was 300–400 p.p.m.; and the soluble K2O was 4200–6200 p.p.m.