Forage availability in summer is critical for sustaining high stocking densities of herbivores on pasture in the eastern U.S. The objective of this study was to determine forage productivity and quality of switchgrass (Panicum virgatum L.) and bluestems [Andropogon gerardii Vitman, Schizachyrium scoparium (Michx.) Nash, and Bothriochloa caucasica (Trin.) C.E. Hubb.l in summer. The experimental site was located in southwestern Pennsylvania on Guernsey silt loam (fine, mixed, mesic Aquic Hapludalf) soil. Two replicates, each containing eight warm-season grasses with different proportions of volunteer cool-season grasses and overseeded legumes were grazed from 1975 to 1977 and then harvested for hay in 1978 and 1979. Pastures were grazed each year in mid-May, late July or early August, and early October. Nitrogen at 0, 45, and 90 kg ha-• and Pat 0, 20, 40 kg ha-• were applied to subplots. 'Blackwell' switchgrass and 'Kaw' big bluestem from the Great Plains readily established stands but did not persist as well as cultivars from the eastern USA. Total annual production from switchgrass-dominated pastures was about 8.0 Mg ha-• and that from 'NY 1145' big bluestem was 6.0 Mg ha-•. Over a 4-yr period, NY 1145 produced about 70% more forage in late July than did Kaw big bluestem. Mean yield distribution of the switchgrass and bluestem pastures was approximately 15% in May, 55% in July-August, and 30% in October. July yield increased about II kg kg-• of N applied. Mean in vitro dry matter disappearance (IVDMD) values for switchgrass and bluestem ranged from 470 to 570 g kg-•, but it was determined that IVDMD underestimated in vivo digestibility by 100 to 200 g kg-•. Crude protein concentration ranged from 70 to 120 g kg-•. Mean crude protein concentration of grass fertilized with 45 and 90 kg N ha-• over a 3yr period was 10 and 26% higher, respectively, than that for unfertilized grass. Overseeded legumes, especially red clover (Trifolium pratense L.), established good stands in warm-season grasses with < 75% stands. Mixed stands of warm-and cool-season grasses and legumes can be maintained under grazing or hay production, with a substantial shift in seasonal yield distribution that can be very beneficial to beef (Bos taurus) producers.Additional index words: Andropogon gerardii Vitman, Bothriochloa caucasica (Trin.) C.E. Hubb., Forage quality, Panicum virgatum L., Schizachyrium scoparium (Michx.) Nash.W ARM-SEASON (C 4 ) perennial grasses such as switchgrass (Panicum virgatum L.) and bluestems [Andropogon gerardii Vitman and Schizachyrium scoparium (Michx.) Nash], were widespread in the northeastern USA before European settlers arrived, which indicates that some genotypes were welladapted to this environment. These indigenous grasses have several metabolic characteristics that set them apart from cool-season (C 3 ) grasses such as Kentucky bluegrass (Poa pratensis L.), orchardgrass (Dactylis glomerata L.), or timothy (Phleum pratense L.). These metabolic characteristics are: higher optimal temperatures for growth (Black ...

Synopsis Light and moisture appear to be critical factors in the establishment of ladino clover seedlings in a well‐fertilized orchardgrass sod. Good establishment was obtained in greenhouse cultures provided with high soil moisture and special techniques to prevent shading by the orchardgrass. Root competition reduced clover dry matter production approximately one‐half. The cause of this growth suppression was not defined, but was suggested to be primarily plant moisture stress.

Nonstructural carbohydrates are sources of readily available energy that enhance rumen microbial activity and forage utilization. Experiments were conducted in Pennsylvania and West Virginia to determine the effect of maturity on total nonstructural carbohydrate (TNC) concentrations in spring herbage of eight grass species and determine TNC concentrations in herbage at immature and mature growth stages on a given day. The grasses were fertilized early each spring and summer with 0, 60, 120, or 240 kg N/ha.Determinations for TNC were made using the Smith takadiastase technique. Mean TNC concentration in the spring herbage of ‘Masshardy’ orchardgrass (Dactylis glomerata L.), ‘Climax’ timothy (Phleum pratense L.), and ‘Sac’ smooth bromegrass (Bromus inermis Leyss.) decreased seven or more percentage units with maturation from vegetative to full bloom stage, but decreased less than four percentage units in ‘Fawn’ tall fescue (Festuca arundinacea Schreb.), ‘Kenblue’ Kentucky bluegrass (Poa pratensis L.), and redtop (Agrostis alba L.). Mean TNC concentration was 50% higher in ‘Pennfine’ perennial ryegrass (Lolinm perenne L.) than in Kenblue Kentucky bluegrass or redtop. Concentration of TNC was inversely related to maximum air and soil temperatures and was affected much more by harvest date than by maturation of the herbage. Concentration of TNC was usually lower in N‐fertilized herbage than in unfertilized controls at early growth stages, but N had little effect on TNC concentration of herbage at full bloom.Maximum yields of TNC were obtained at the stem elongation stage with ryegrass, at flower‐head emergence with Pennmead orchardgrass and ‘Ky. 31’ tall rescue, and at full bloom with other grasses. N fertilization increased TNC yield of orchardgrass, tall rescue, and reed canarygrass; decreased TNC yield of smooth bromegrass and redtop; and had little effect on TNC yield of ryegrass and timothy.

Additional information on Mg status of temperate‐origin forages under cool temperatures is needed if economic losses from grass tetany are to decrease. A greenhouse study was conducted to determine temperature and Mg fertilizer effects on herbage Mg concentration of one or more cultivars of tall rescue (Festuca arundinacea Schreb.), timothy (Phleum pratense L.), reed canarygrass (Phalaris arundinacea L.), smooth bromegrass (Bromus inermis Leyss.), orchardgrass (Dactylis glomerata L.), redtop (Agrostis gigantea Roth.), perennial ryegrass (Lolium perenne L.), Kentucky bluegrass (Poa pratensis L.), alfalfa (Medicago sativa L.), red clover (Trifolium pratense L.), ladino and white clover (T. repens L.), alsike clover (T. hybridum L.), birdsfoot trefoil (Lotus corniculatus L.), and crownvetch (Coronilla varia L.). Plants were grown in Hagerstown soil, which belongs to the mixed, mesic family of typic Hapludalfs, in 4‐liter pots under natural daylength at cool (X̄ = 14 C), intermediate (X̄ = 18 C), and warm (X̄ = 26 C) ambient temperatures. Two levels of fertilizer Mg were used (0 and 672 kg Mg/ha as MgSO4). Grasses received 1,300 kg N/ha as NH4NO3 and both grasses and legumes were supplied K2SO4 to furnish 600 kg K/ha over a 13‐month growing period. Herbage was harvested at 2 to 3‐week intervals at a height of 5 cm. Under cool temperatures, in both spring and autumn, and with added Mg, cultivars having high Mg levels were ‘Timfor’ timothy, ‘Nordstern’ orchardgrass, and ‘Viking’ birdsfoot trefoil. Species and cultivar rankings were similar for spring and autumn but Mg concentration was greater in autumn, indicating that cool temperatures, per se may be less limiting to Mg accumulation than previously thought. Marked differences, five to seven‐fold, in Mg concentration occurred between species and cultivars of both grasses and legumes in response to Mg fertilizer. Low K/(Ca + Mg) ratios were obtained when the grasses were harvested under cool autumn temperatures. Yields were unaffected by Mg fertilization. The consistency of cultivar ranking for Mg levels over a wide temperature range and different soil Mg levels, suggest that cultivar selection for Mg accumulation would be rewarding. Cultivars inherently efficient in Mg uptake, especially at cool temperatures, may help prevent grass tetany.

Ladino clover grown in greenhouse solution culture was separated into leaflets, petioles, stolons, flowers, peduncles, crowns, and roots and each part analyzed for P, K, Ca, Mg, Mn, Fe, Cu, B, Al, and Zn content. Leaflets and petioles of three different ages were also analyzed for these 10 elements. Phosphorus was concentrated in flowers; Al in leaflets; and Mg, Mn, and Fe in the roots. With increasing age of leaves the P and Zn contents markedly declined, whereas Ca increased. Phosphorus treatments affected P concentrations in leaflets without appreciably affecting P distribution patterns.