Rate of absorption and translocation of mineral nutrients by potatoes in Aroostook County, Maine, and their relation to fertilizer practices

A study was made from 1938 to 1940 at Aroostook Farm, Presque Isle, Maine, to determine the rate of and total absorption of nitrophosphoric acid, potash, calcium oxide, magnesia, and sulfur by different varieties of potatoes when these nutrients were supplied at varying rates under Aroostook County conditions. Data obtained in 1939 with the Green Mountain variety fertilized with an average of 2,500 pounds of 4-8-8 per acre are presented. The Green Mountain variety of potato elaborated 50% of its total dry weight during the 31-day period 51 to 81 days after planting. During the first 50 days after planting the Green Mountain variety absorbed 8.1% of the total major nutrients while producing only 3.2% of the total growth. Of the total amount of the six major nutrients absorbed during the season, 71% was absorbed during the 31-day period 51 to 81 days after planting. The absorption of nutrient elements occurs relatively more rapidly than the elaboration of dry matter during the early stages of growth. The reverse situation takes place during the latter part of the growing season. The peak rate of absorption of nutrients was found to occur approximately 10 days prior to the peak rate of dry matter elaboration. The peak rate of absorption of nutrients occurred during the interval 61 to 70 days after planting, or 30 to 40 days after emergence. During this period 27.1% of the total nutrients taken up during the season were absorbed. In 1939, during this 10-day period of maximum absorption, an acre of potatoes absorbed the following approximate amounts of nutrients in pounds per acre per day: Nitrogen, 3.8; phosphoric acid, 0.6; potash, 6.4; calcium oxide, 1.6, magnesium oxide, 0.9; and sulfur, 0.3. The highest contents of nutrients found in potato plants with tubers included of the Green Mountain variety fertilized with an average of 2,500 pounds of 4-8-8 under 1939 conditions were about 143 pounds of nitrogen (N), 26 pounds of phosphoric acid (P2O5), 232 pounds of potash (K2O), 56 pounds of calcium oxide (CaO), 30 pounds of magnesia (MgO), and 11 pounds of sulfur (S) per acre. A larger crop such as produced under 1943 conditions absorbed larger quantities of these nutrients, particularly N and K2O. The proportion of the nutrients absorbed that were translocated into the tubers was approximately as follows: four-fifths of the P2O5, two-thirds of the nitrogen, six-tenths of the sulfur, one-half of the K2O, four-tenths of the MgO, and about one-twentieth of the CaO. The tubers in the 387-bushel crop under 1939 conditions contained 95 pounds of nitrogen, 20 pounds of P2O5, 117 pounds of K2O, 3.2 pounds of CaO, 12 pounds of MgO, and 6 pounds of S. The relation of the rate and amount of absorption and translocation of mineral nutrients by potatoes in Aroostook County, Maine, to fertilizer practices is discussed.