Potassium Nutrition of Alfalfa and Other Forage Legumes: Temperate and Tropical

Potassium (K) is an essential element for forage legumes. It plays a vital role in the nutrition and production of alfalfa and other forage legumes in the temperate, subtropical, and tropical regions. Forage legumes can utilize K from exchangeable and nonex-changeable soil reserves, although their use of nonexchangeable K in surface soil layers may be less than that of grasses. Alfalfa root activity at various soil depths may be reflected in the uptake of more easily measured parameters than soil K. Recommendations for K application to forage legumes generally include an amount to increase the available K+ when the soil test level is initially low. Application rates under high fertility conditions are more difficult to determine than under deficiency conditions because of the normal lack of yield response and the ability of the forage legumes to utilize various soil reserves throughout a large soil volume.