Fitting Plants Nutritionally to Soils. II. Cotton1

Fifteen cotton varieties (Gossypium hirsutumL.), representing germplasm recommended for different areas of the United States, were subjected to Fe, Zn, and Cu stresses and Al and Mn toxicities to determine their nutrient requirements. They were grown on the seven different soils described in part I of this study for soybeans. All cotton varieties grown on Quinlan soil (Fe stress) developed deficiency symptoms that were similar to symptoms produced in cotton grown on Shano and Taunton soils (Zn stress). On Quinlan and Taunton soils, the plants responded to both Fe and Zn. Iron added to Taunton soil decreased the uptake of Fe and increased the uptake of Zn by the plants. Lime added to Richland soil induced a Zn deficiency that increased Fe uptake by the plants. When Zn was added to this soil, yields increased and Fe uptake decreased in the plants. All 15 cotton varieties grew poorly on acid Bladen soil (Al toxic), and yields were doubled by liming and yield of C‐7105, 73‐319 doubled again by adding Cu. Best yields, with no toxicity symptoms, were obtained on Richland soil (Mn toxic). Cotton and soybean had different nutrient requirements. For example, cotton was Cu and Zn inefficient and Mn tolerant, whereas soybeans were Cu and Zn efficient and Mn intolerant in most varieties tested.