Forage Potential of Irrigated Blue Grama with Nitrogen Fertilization

Abstract

In 1959, ammonium nitrate was surface applied to blue grama at rates of 0, 200, 400, and 800 lb N/acre. Initial plant response to fertilizer N was measured in 1959, and residual response in 1960 and 1961. High moisture levels were maintained by irrigation. Each increment of applied N increased forage yields and yield trends indicate that with adequate water and N blue grama will produce at least 7,500 lb/acre/year of oven-dry forage. Recovery of added N was very low, ranging from 28 to 34% for the 200- and 800-lb rates, respectively. Total water use was similar for all treatments, but pounds of forage produced per inch of water used increased with each increment of N. The results indicate blue grama is a relatively inefficient user of moisture and N when compared with sudan grass, bermuda grass, and some other introduced grasses. However, further studies are needed to determine if blue grama can be managed to use fertilizer and water more efficiently.