Description
Balanced nutrition of phosphorus (P) and potassium (K) is needed for improving alfalfa (Medicago sativa L.) productivity. Availability and uptake of P and K by alfalfa for yield response can depend on their relative levels with soil calcium (Ca2+) and magnesium (Mg2+) in combination with harvest management. An experiment was conducted at the University of Wyoming Sustainable Agriculture Research and Extension Center to determine the alfalfa’s response to P and K in association with Ca, Mg, and harvest time. Treatments were 10 selected combinations (kg ha-1) of three levels of P (0, 34, and 67 P2O5), three K (0, 168, and 336 K2O), two Ca (0 and 560 CaO), and two Mg (0 and 56 MgO), and two harvest time (early harvest, late bud to early [10%] bloom; late harvest, 7 days after early harvest). The study design was a randomized complete block with three replications. The 67 kg P2O5 ha-1 and 336 kg K2O ha-1 combination gave the highest total annual forage yield at early harvest ( > 12.5 Mg ha-1; more than 40% increase over the control) and late harvest ( > 14 Mg ha-1; more than 40% increase over the control), either with or without association of high Ca and Mg levels. At late harvest, 67 kg P2O5 ha-1 and 336 kg K2O ha-1 combination produced the highest forage yield ( > 16 Mg ha-1 ; 60% increase over the control) in association with high Ca and Mg levels. Fertilizing alfalfa with high rates of P and K on soils in combination of Ca and Mg levels, under early and late harvest schedules has shown high yield response. Growers are encouraged to consider applying increased P and K rates to alfalfa, even on soils with high Ca and Mg levels, while delaying harvest for few days for an improved alfalfa production.
Included in
Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, Weed Science Commons
Alfalfa Response to Phosphorus and Potassium Fertility and Harvest Management
Balanced nutrition of phosphorus (P) and potassium (K) is needed for improving alfalfa (Medicago sativa L.) productivity. Availability and uptake of P and K by alfalfa for yield response can depend on their relative levels with soil calcium (Ca2+) and magnesium (Mg2+) in combination with harvest management. An experiment was conducted at the University of Wyoming Sustainable Agriculture Research and Extension Center to determine the alfalfa’s response to P and K in association with Ca, Mg, and harvest time. Treatments were 10 selected combinations (kg ha-1) of three levels of P (0, 34, and 67 P2O5), three K (0, 168, and 336 K2O), two Ca (0 and 560 CaO), and two Mg (0 and 56 MgO), and two harvest time (early harvest, late bud to early [10%] bloom; late harvest, 7 days after early harvest). The study design was a randomized complete block with three replications. The 67 kg P2O5 ha-1 and 336 kg K2O ha-1 combination gave the highest total annual forage yield at early harvest ( > 12.5 Mg ha-1; more than 40% increase over the control) and late harvest ( > 14 Mg ha-1; more than 40% increase over the control), either with or without association of high Ca and Mg levels. At late harvest, 67 kg P2O5 ha-1 and 336 kg K2O ha-1 combination produced the highest forage yield ( > 16 Mg ha-1 ; 60% increase over the control) in association with high Ca and Mg levels. Fertilizing alfalfa with high rates of P and K on soils in combination of Ca and Mg levels, under early and late harvest schedules has shown high yield response. Growers are encouraged to consider applying increased P and K rates to alfalfa, even on soils with high Ca and Mg levels, while delaying harvest for few days for an improved alfalfa production.
