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 Bouteloua and Andropogon sp., with some Panicum and Sorghastrum sp., were evaluated for dry matter (DM) yield for 3 years and crude protein (CP) and in vitro dry 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.

Brassica spp. may serve as high-quality forage crops in parts of the Southern Great Plains when most warm-and cool-season forages are unproductive. Field studies were conducted to assess the forage (shoot and/or root) yields, crude protein (CP), and digestibility (IVDMD) of turnip root crops (Brassica rapa L., 'Purpletop', 'Cyclon', 'Frisia', and 'Tyfon'; a chinese cabbage X stubble turnip hybrid) and leafy-stem crops ('Winfred' rape (B. napus L.) and 'Merlin' kale (B. oleracea L.)] at different harvest dates. All six Brassicas were established on a Dale silt loam soil (fine-silty, mixed, thermic, Pachic Haplustoll) in September 1982 (fall) and March 1983 under dryland conditions. Shoot dry matter (DM) production for root crop cultivars was highest 8S and 9S days after planting In fall and spring, respectively. The greatest total plant DM yield was produced by Cyclon in the fall and Purpletop in the spring (7.4 and 7.6 Mg ha-t, respectively). Cyclon and Tyfon produced 0.7 Mg ha-1 more shoot DM, whereas Purpletop and Frisia produced 0.4 to 0.9 Mg ha-1 more root DM during their maximum DM production period. In early harvests, DM yields of kale were less than those of rape, but after 90 days growth, yields were similar (7.0 Mg ha"" 1 ). Shoot CP levels of root crops averaged 220 g kg-1 and were about 2S to 60 g kg-1 greater than root levels. The IVDMD of roots ranged from 670 to 840 g kg-1 and were approximately 60 to 120 g kg-1 higher than values for shoots. Levels of DM, CP, and IVDMD for all cultivars were similar or better in fall growing season and did not decline as rapidly compared with spring. Cyclon and Purpletop have the potential to provide high yields of high-quality forage during the forage deficit periods of Southern Great Plains.

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Old World bluestems (Bothriochloa spp.) have been used in the U.S. for over 60 years but few data are available on effects of management or cuitlvar differences for forage yield and quality. Field experiments were conducted on a Kirkland silt loam (Uderic Paleustoii) soil for 2 years (198E83), in order to asseas the yield and quality of 4 such cultivars as affected by maturation and plant part. The experimental design was a split-split plot, in a randomized complete block, with 4 replications, 4 cuitivars ('Caucasian', 'Canada', 'Plains', 'WW Spar'), 10 harvest dates, and 3 piant parts (whole piant, stem, and leaf). Cuitlvarr were main plots; harvest dates and plant parta were sub and sub-sub plots, respectively. Response variables were dry matter yield (DMY), in vitro dry matter disappearance (IVDMD), leaf to stem ratio (L/S), and in vitro digestible dry matter yield (IVDDMY). Canada consistently had the lowest leaf, stem, and whole plant DMY and IVDDMY. Caucasian had higher leaf, stem, and whole plant DMY and IVDDMY than Plains and WW-Spar in 1983, but the DMY and IVDDMY of these cultivars were simile in 1982. Quadratic and linear equations were satisfactorily 5t to the DMY and IVDDMY data in 1982 and 1983, respectively. The IVDMD ln whole piant samples decreased at average rates of 4.2 and 5.5 g kg ha-' da5y in 1982 and 1983, respectively, during harvest week one. Among cultivars, Caucasian had the highest rate of decline and Ganada the lowest. The decline was quadratic in nature and faster in stem fractions. Cuitivu IVDMD differences were consistent over plant parts. Ganada and Cawasian had the highest and lowest IVDMD concentrations, respectively. Plains and WW-Spar had IVDMD values of slm5ar magnitude and intermediite to those of Ganada and Caucasian. Cuitivar leaf to stem ratios were shnilu in 1982 but different in 1983 with Plains and Caucasian having higher L/S ratios than Ganada and WW-Spar. For these cultivars leafiness was a poor indicator of digestibility.

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