Effect of soil applications of potassium, magnesium sulfate and magnesium sulfate spray on potato yield, composition and nutrient uptake

Abstract

A series of replicated field studies conducted in the Matanuska Valley of Alaska from 1961 through 1963 compared the response of potatoes to two K sources, K rates, and the soil and spray applications of magesium sulfate. Foliage and tubers were analyzed for N, P, K, Ca, and Mg. Each year K applications increased US No. 1 yield and tuber K removal and reduced the number of plants showing foliar necrosis in July and the yield of tubers showing brown sunken lesions, at the stolon end. In two of the three years K fertilizer increased the sum of the cations (K, Ca, and Mg) in the tubers and decreased the dry matter, N and P content and Ca/Mg ratio of the tubers, and the content of Mg and sum of the cations (K, Ca, and Mg) in the tops. K increased N, P, Ca, and Mg removal by Kennebec tubers in 1963. Each K increment increased the K content of the potato foliage and tubers, the Ca/Mg ratio of the foliage and K, Ca, and Mg removal by the tubers but reduced the content of Mg in potato foliage. The highest K rate depressed the Ca content of potato foliage. Magnesium sulfate applications depressed the K content of both potato foliage and tubers in 1961 and the P content of the tubers in 1962. Magnesium sulfate sprays increased the K content of potato foliage but depressed the K content of the tubers and K removal by the tubers. Soil or spray applications of magnesium sulfate had no significant effect on yield, K deficiency symptoms, N, Ca, Mg percentage or removal, Ca/Mg ratio, or sum of the cations (K, Ca, and Mg).