• Chemical Composition of Native Range Grasses Growing on Saline Soils of the South Texas Plains

      Everitt, J. H.; Alaniz, M. A.; Gerbermann, A. H. (Society for Range Management, 1982-01-01)
      During the growing seasons of 1976 and 1977, six native range grass species and a composite of miscellaneous grasses growing on Saline Clay and Rolling Hardland range sites (both sites have saline soils) in south Texas were analyzed for percentage content of crude protein (CP), P, Ca, Mg, K, and Na. Levels of CP, P, K, and Na were generally highest after periods of adequate rainfall in late spring, summer, and early fall and lowest in late fall as the grasses went into dormancy. Levels of Ca and Mg remained relatively stable through the growing season and showed little relationship to rainfall. Grasses from the Saline Clay site had slightly higher levels of the chemical constituents than those grasses from the Rolling Hardland site.
    • Decomposition of Common Curlymesquite Herbage on Edwards Plateau Rangeland, Texas

      George, J. F.; Smeins, F. E. (Society for Range Management, 1982-01-01)
      Decomposition of common curlymesquite herbage from a continuously, heavily grazed pasture and one pasture of a 4-pasture deferred rotation grazing system was investigated on the Edwards Plateau of Texas. Decomposition of herbage in litterbags was similar for both pastures. Approximately 40% of the original herbage weight was lost during the 345-day study. Average decomposition rate was 2.19 mg/g/day. Rate of decomposition during a 238-day period was significantly related to antecedent potential evaporation and precipitation since the preceding collection date and cumulative time. Percentage nitrogen and percentage ash content increased while percentage carbon and carbon/nitrogen ratio decreased over time in the decomposing herbage.
    • Prescribed Burning during Winter for Maintenance of Buffelgrass

      Hamilton, W. T.; Scifres, C. J. (Society for Range Management, 1982-01-01)
      Neither a single burn during late winter nor a second burn 2 years later reduced the density of mixed brush dominated by blackbrush acacia, honey mesquite, and twisted acacia which had invaded buffelgrass seedings on the South Texas Plains. Based on canopy cover and height, most woody species had recovered to preburn status after two growing seasons. Buffelgrass responded by a flush of spring growth during the year of burning and cumulative herbage production exceeded that of unburned areas for three growing seasons after the single burn. However, during dry growing conditions, less buffelgrass herbage was produced on burned than on unburned areas. A second burn tended to increase buffelgrass herbage production compared to the single burn. However, when moisture became limiting, less herbage was also produced on the twice-burned areas. Disappearance of buffelgrass, attributed primarily to grazing, closely paralleled herbage production, with the greatest disappearance occurring the first growing season after the burn.
    • Response of Chihuahuan Desert Mountain Shrub Vegetation to Burning

      Ahlstrand, G. M. (Society for Range Management, 1982-01-01)
      The effects of fire on vegetation in the desert mountain shrub community were studied on 3 to 7-year-old burned sites near the northern limits of the Chihuahuan Desert. Coverage and frequency of redberry juniper (Juniperus pinchotii) and frequency of whiteball acacia (Acacia texensis) were lower, while frequencies of catclaw mimosa (Mimosa biuncifera) and skeleton goldeneye (Viguiera stenoloba) were higher on burned sites when compared with unburned paired plants. Lechuguilla (Agave lecheguilla), sotol (Dasylirion leiophyllum), and sacahuista (Nolina spp.) suffered losses in excess of 50% on burned sites. With the exceptions of sideoats grama (Bouteloua curtipendula) and bull muhly (Muhlenbergia emersleyi), all grasses had recovered or showed increases by the end of three growing seasons. All grasses had recovered or increased on 6 to 7-year-old burns. Recovery of burned plants was predominately by vegetative means, suggesting that periodic fires can be used to maintain or even increase grass coverage at the expense of shrubs in this community.
    • Seasonal Diurnal Variation in Composition of Cow Diets

      Kirby, D. R.; Stuth, J. W. (Society for Range Management, 1982-01-01)
      Seasonal diets between fall 1977 and spring 1979 were collected in morning and evening from esophageally fistulated cows in the Post Oak Savannah of east-central Texas. Chemical content of diurnal diets were similar within a season except CP was higher in evening collections as compared to morning collections during fall. Cows appeared to select for energy (IVDOM) over CP. Botanical composition of morning and evening diets differed only during summer. Since the cows spent more time during hot summer afternoons in the shade of woody plants, less grass and more forbs, vines, and woody vegetation were selected. Research based on morning diet collections only might result in biased samples. Recognition of nutritional and environmental stresses with potential to alter grazing behavior of animals is critical for accurate sampling of livestock diets.