Timing of Nitrogen Fertilizer Application for Annual Ryegrass Overseeded into Unimproved Perennial Warm‐season Pasture

Successful production of herbage by cool‐season forage grasses in the southern Plains is heavily dependent on a sufficient supply of available nitrogen (N), and appropriate scheduling of N application is an important component of cost‐effective fertilizer use. The effects of different combinations of fall, early‐spring, and late‐spring increments of 22.3 lb N/acre on herbage dry matter (DM) and N yields of annual (Italian) ryegrass (Lolium multiflorum Lam.) were tested over 3 yr. Fall N application had minimal effect on ryegrass establishment, measured in plant or tiller counts in the following spring. Application of N in fall did not produce harvestable herbage DM in fall and provided significant increase in DM yield in the following spring in only one year out of three. Early‐spring N application produced significant yield increase in two out of three years and provided a mean yield response of 17.2 lb DM/lb N applied. Application of N for regrowth after initial ryegrass harvest in early May produced a mean yield increment of 6.7 lb DM/lb N applied. There was no residual effect of fall or spring N application on warm‐season grass production. Limited N supply (