Effect of nitrogen fertilization and slashing on the Priebe prairie grass (Bromus uniofoides) component of an irrigated pasture

Abstract

The effect of 200 lb/ac/annum of nitrogen applied as urea in split applications, and of regular slashing after each grazing, was studied for 3 years on an irrigated sward. The pasture initially consisted of 20% Priebe prairie grass and 75% Ladino white clover. Inadequate summer irrigation caused the clover to largely disappear from the sward in the first 15 months of the study. This was accompanied by summer grass invasion. Very marked responses by the prairie grass occurred as the clover disappeared from the sward and the rate of cool season nitrogen application was increased. Over the 1966 season, nitrogen increased the total yield of prairie grass from 1,105 lb/ ac oven-dry matter to 7,618 lb/ac. Nitrogen depressed clover yield on one occasion. At the end of the trial the nitrogen fertilized sward was composed of 7 5 % prairie grass and equal proportions of clover and weeds. Slashing after each grazing decreased yield of prairie grass on only three occasions