Effect of fertilizers on yield and quality of potatoes in the Willamette Valley

Published October 1967. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalogInformation contained within documents may be obsolete. Please check for recent information at the OSU Extension Service website: http://extension.oregonstate.edu/catalog/results.php?cat=AgricultureData from fertilizer experiments with potatoes in the Willamette Valley from\ud 1961 through 1971 show that responses have been measured from nitrogen, phosphorus,\ud potassium, magnesium, and lime. Responses from these nutrients have been\ud related to soil and/or plant analysis values.\ud In recent years most of the potato production has moved from hill soil areas to\ud valley floor soils with much of the production following cereal crops with the straw\ud disced or plowed into the soil before planting potatoes. These experiments show that\ud 150 to 200 pounds of nitrogen per acre should be applied for April-planted potatoes\ud following a cereal crop, and this rate should be reduced to 50 to 100 pounds of nitrogen\ud per acre for late May plantings or where potatoes follow a heavily fertilized\ud row crop.\ud There was a response from band application of phosphorus on all locations.\ud Rates of phosphorus application should be increased from about 80 to about 160\ud pounds of phosphorus (P2O,) per acre when phosphorus soil test values drop below\ud 40 parts per million.\ud One hundred pounds of potassium (K2O) per acre should be applied when\ud soil analyses range from 300 to 400 ppm potassium (K). Magnesium fertilizer should\ud be added when soil test values are below 0.8 milliequivalents magnesium per 100\ud grams of soil. Application of lime the fall before planting should be considered\ud when the soil pH is below 5.5 and soil analysis shows 5 milliequivalents of calcium\ud per 100 grams of soil or less