Effects of Fertilizing and Applying Herbicide on Yield, Quality and Expected Profitability of Native Grass

Fertilization of native grass hay fields and pastures is generally not recommended in Oklahoma. A 2-year, 2-location study was conducted in south-central Oklahoma to evaluate the effect of fertilizer and herbicide use on yield, quality, and profitability of native grass systems. Five fertilizer rates (0-0-0, 50-0-0, 100-0-0, 50-50-0, and 100-50-0 lb N-P₂O_5--K₂O/acre) with and without herbicide were applied. Plots were harvested in July and again after frost to mimic a hay harvest followed by grazing stockpiled forage. Fertilization significantly increased forage yields, especially where P was added to N, but the yield increases were not profitable. Forage quality was generally unaffected by fertilizer and herbicide use. Fertilization and herbicide application together in native grass hay fields and pastures are not justified by the results of this study due to economic reasons.