Kura Clover Response to Potassium Fertilization

Abstract

Kura clover (Trifolium ambiguum M.B.) is a persistent perennial forage legume that produces high-quality herbage for grazing, but its response to potassium (K), an essential plant nutrient, is unknown. Our objective was to determine the effect of four dipotassium oxide (K 2 O) rates on forage yields and stands of Kura clover compared to birdsfoot trefoil (Lotus corniculatus L.) and alfalfa (Medicago sativa L.). There was a significant linear response in Kura clover and alfalfa forage yields to K 2 O fertilization each year. Averaged over 4 years, Kura clover forage yield increased by 0.024 Mg ha -1 per kg of K 2 O applied, and the yield response was similar for alfalfa. Birdsfoot trefoil forage yield response to K 2 O fertilization was less than those of alfalfa and Kura clover. In the first 2 years after seeding, Kura clover forage yields were consistently less than for alfalfa at all rates of K 2 O fertilizer, but in subsequent years Kura clover yields were similar to or exceeded those of alfalfa. Final groundcover values, an estimate of stand density, of unfertilized (0 K 2 O rate) Kura clover, birdsfoot trefoil, and alfalfa were 86, 35, and 21%, respectively. Final groundcover of Kura clover and alfalfa was increased by K 2 O fertilization. We conclude that Kura clover has good persistence with low soil K fertility but stands and yields can be increased by fertilization.