Mineral Nutrition of the Cotton Plant.

The accumulations and partitions of mineral elements and dry matter in upland cotton plants were followed: A, at five-day intervals for thirty days starting with the seed with the plants growing in Hoagland's solution in a warm-to-hot summer greenhouse, and B, at 15-day intervals from thirty days after planting to maturity in field plantings. The latter data are not original but are recalculated from Olson and Bledsoe (16) who sampled cotton growing on Cecil sandy loam in Georgia; their results were the averages of two fertilizer treatments for the years 1939 and 1940 on a soil that had a pH 5.7, 2 % organic matter, and which produced 2,000 pounds per acre of seed cotton. The data were reported by them as pounds-per-acre increments of N, P205, K20, CaO MgO, and plant weight for 15-day periods, together with the end-of-season totals. The Olson-and-Bledsoe data long have been regarded by us as especially meritorious and deserving of the additional analyses and interpretations which we have undertaken in this paper. As an orienting foreword, some rather marked differences occurred in the mineral accumulations, and particularly in growth rates between the plants grown in the greenhouse in Hoagland's solution for thirty days and those first sampled in the field by Olson and Bledsoe at a like age after development during the typically cool conditions of the spring. The kernels of the Empire seed planted in the greenhouse had an average dry weight of 0.063 gm ; at 30 days the leaves and stems had dry weights of 2.93 gm. In the field at thirty days the plant tops weighed only 0.13 gm. The greenhouse-to-field ratios of mineral accumulations (percentages on dry weight of leaves and stems) at thirty days were N, 4.0 to 3.5; P, 0.8 to 0.3; K, 4.5 to 2.7; Ca, 3.3 to 3.1; and Mg, 0.7 to 1.4.