Phosphorus and potassium management in alfalfa production under varied calcium and magnesium soil conditions with harvesting regimes

Forage productivity is intrinsically linked to soil nutrient availability, influenced by soil pH, moisture, texture, organic matter, available nutrients, crop and cultivar selection, and climate. Alfalfa's (Medicago sativa L.) high demand for phosphorus (P) and potassium (K) can deplete soil reserves by up to 120 kg P ha⁻¹ year⁻¹ and 400 kg K ha⁻¹ year⁻¹, necessitating informed fertility management strategies for enhanced yield and quality. Simply applying P and K alone is insufficient without considering relative concentrations of other nutrients such as soil exchangeable calcium (Ca) and magnesium (Mg) and cutting schedules. This review explores optimal fertility practices, including integrated nutrient management and harvest timing. It underscores the need for further research to investigate the interactions involving P, K, Ca, and Mg on alfalfa's agronomic performance. It aims to clarify the mechanisms of nutrient availability and uptake, correlate nutrient management with harvest timing, and develop region-specific fertility programs that account for K, Ca, and Mg-rich soils. For example, studies suggest that an integrated nutrient management approach can increase alfalfa yield by 15%–20% and improve forage quality. By addressing these needs, growers can enhance alfalfa productivity, optimize forage yield and quality, and support sustainable agricultural practices. The review concludes that integrating nutrient management with harvest timing can be critical to the maintenance of a healthy and productive alfalfa stand, leading to more resilient and sustainable forage production. This integrated approach represents a novel strategy in optimizing alfalfa cultivation, paving the way for future research and advancements in sustainable agriculture.