YIELD RESPONSE OF BERMUDAGRASS AND BAHIAGRASS TO APPLIED NITROGEN AND OVERSEEDED CLOVER

Models can be used to describe yield response of grasses to applied N and other management factors. This analysis was performed to show interactions between applied N and overseeded clover on dry matter yield, and to estimate equivalent N supplied by clover. Data from three locations were used. At Watkinsville, GA both 'Coastal' and common bermudagrass [Cynodon dactylon (L.) Pers.] were over-seeded with crimson clover (Trifolium incarnatum L.). At Eagle Lake, TX, both Coastal bermudagrass and 'Pensacola' bahiagrass (Paspalum notatum Flugge) were overseeded with 'Yuchi' arrowleaf (Trifolium vesiculosum Savi) and 'Mt. Barker' subterranean (Trifolium subterranean L.) clovers. At Jay, FL both Coastal bermudagrass and Pensacola bahiagrass were overseeded with crimson clover. The logistic model described dry matter response to applied N and contained three parameters (A, b, c). It was shown that the presence of clover affected only the b coefficient, which related to yield at zero applied N. It was also shown that overseeded clover provided equivalent N of approximately 120 kg ha-1 for bermudagrass and 90 to 220 kg ha-1 for bahiagrass. Most of the increased yield of the bermudagrass-clover combination over bermudagrass without clover was due to the clover production; only about 25 kg ha-1 of equivalent N was carried over to the bermudagrass under conditions where top growth of clover was removed. The model allows quantitative estimates of equivalent N supplied by clover.