| Abstrakt: |
Several perennial, warm‐season grass species are being used to revegetate depleted rangeland in parts of the southern Great Plains, particularly Oklahoma and Texas. This experiment was conducted to provide comparative data on the yield and quality of forage of three introduced grasses and a native range grass mixture as influenced by nitrogen and phosphorus fertilization. ‘Midland’ bermudagrass [Cynodon dactylon(L.) Pers.], ‘Morpa’ weeping lovegrass [Eragrostis curvula(Schrad.) Nees], ‘Plains’ bluestem [Bothriochloa ischaemum(L.) Keng var. ischaemum] and an existing native range grass mixture consisting largely of Boutelouaand Andropogonsp., with some Panicumand Sorghastrumsp., were evaluated for dry matter (DM) yield for 3 years and crude protein (CP) and in vitrodry matter digestibility (IVDMD) for 2 years under four levels of N and two of P. Levels of N were 0, 67, 135, and 269 kg/ha applied annually in split applications. Levels of P were 0 and 90 kg/ha; the 90 kg level applied annually in a single March application. All grasses and the range mixture responded to increasing N levels with increased DM yield and CP percentage. The three introduced grasses also responded to increasing N levels with increased IVDMD, but the native range mixture did not. The three introduced grasses and the native range mixture responded in yield to application of 90 kg/ha of P. Yield response to P was significant and increased in response with increasing amounts of N. This response was greatest at the 135 and 269 kg/ha N levels. The addition of P had no discernible effect on the IVDMD of the introduced grasses or native range mixture but decreased their CP percentage. Significant interactions included grass (G) × N, G × P, G × year, and N × P. Morpa weeping lovegrass and Plains bluestem were more productive than Midland bermudagrass, particularly in the absence of and at the 67 kg/ha N level. At the higher N levels, Midland bermudagrass was most responsive to P. The native range mixture was least responsive to N and P fertilization and its DM yield was significantly less than that of the other three grasses. |
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