Optimum Nutrient Levels in Potato Leaves (Solanum tuberosum L.)
1966
MacKay, D. C. | MacEachern, C. R. | Bishop, R. F.
Field experiments involving six rates of each of the nutrients N, P, and K were conducted at 18 locations over a 3-year period. Comparison of polynomial response curves for tuber yields with those for nutrient content of uppermost mature leaves collected at the 10% bloom stage suggested optimum levels of 6.5, 0.50, and 3.9% for N, P, and K, respectively. The optimum level for K was the most satisfactory of the three nutrients because moderate yield deficiencies resulted in large differences in leaf concentrations. However, on soils high in exchangeable K, responses to K fertilization were obtained at higher leaf levels than on soils low in K. The optimum level derived for N appeared to be fairly stable. On coarse-textured soils, or where a combination of factors produced unusually high yields, somewhat higher leaf levels, at the stage sampled, were apparently necessary to prevent deficiency. The optimum level obtained for P was the least satisfactory, since there was considerable variation as a result of season and soil series. However, where yields were < 90% of the maximum, the P content was invariably well below the overall optimum value.
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