• Nodulation and Acetylene Reduction by Certain Rangeland Legume Species under Field Conditions

      Johnson, D. A.; Rumbaugh, M. D. (Society for Range Management, 1981-05-01)
      Acetylene reduction rates, N2[C2H2], were obtained to estimate nitrogen fixation by several introduced and native range legume species. The N2[C2H2] fixation rates of excised root segments with attached nodules were measured in the field for legumes from two mountain grassland sites, one native sagebrush-dominated site, and three cultivated former big sagebrush study sites. Sampling was conducted in the driest part of the growing season. Even during this high stress period, nodules were present and active in some legume species. Medicago sativa plants were particularly notable because of their capability of being nodulated and ability to reduce acetylene in dry soils when other legumes were not active. In addition, under the most favorable environmental conditions in this study, nodules from M. sativa reduced acetylene most actively at a rate of 26.2 micromoles ethylene/h/g nodule fresh weight. Although nodulation was generally less successful in New World than Old World lupine species, Lupinus mutabilis was capable of reducing acetylene at a rate of 4.97 micromoles ethylene/h/g nodule fresh weight, even in a severely water stressed environment. These results suggested that some legume species may be capable of fixing significant amounts of nitrogen on semiarid range sites.
    • Preliminary Observations on the Performance of Some Exotic Species of Atriplex in Saudi Arabia

      Hyder, S. Z. (Society for Range Management, 1981-05-01)
      Seeds of seven different Atriplex species (four from the United States and three from Australia) were germinated in the greenhouse and then transplanted to field plots at the Regional Agriculture and Water Research Center (RAWRC), located at Riyadh, Saudi Arabia. Data were obtained on vegetative growth, flowering, seed production, seed germination, and chemical composition of the plants. There were marked differences between species in vegetative growth. All flowered normally, but seed production and seed germination percentages differed among the species. All species were high in protein and ash content. Further field studies are underway at different sites within the Kingdom to test the potential value of Atriplex for the improvement of Saudi Arabian rangeland.
    • Response of Bobwhites to Cover Changes within Three Grazing Systems

      Hammerquist-Wilson, M. M.; Crawford, J. A. (Society for Range Management, 1981-05-01)
      In south Texas bobwhites responded to short-term changes in the amount of vegetative cover within three grazing systems, two rotational and one continuous. Use by quail apparently was related to increases in amounts of bare ground and forb cover and decreases in grass cover.
    • Response of Western North Dakota Mixed Prairie to Intensive Clipping and Five Stages of Development

      Holderman, C. A.; Goetz, H. (Society for Range Management, 1981-05-01)
      The effects of clipping to a 2.54 cm (1 inch) height at 5 stages of development of western North Dakota mixed prairie were investigated. Soil moisture content at the beginning of the growing season had a greater effect on yields than did the clipping treatments. Observations from this two-year study indicate that soil moisture removal was not affected by the clipping treatments. Clipping significantly affected peak yields by needle-and-threadgrass (Stipa comata) and the Carex species during 1977; and the miscellaneous grasses (Agropyron smithii and Agropyron subsecundum) during 1978, at the sandy loam site. No significant differences in yields were observed for the other species and groups at the sandy loam site, or, the species and groups at the loam site for the two-year-period.
    • Root Biomass Calculation Using a Modified Counting Technique

      Schafer, W. M.; Nielsen, G. A. (Society for Range Management, 1981-05-01)
      Data on root weight, length, and surface area are useful in soil characterization, ecosystem description, and studies of plant-soil interaction. Characterization of root systems is often thought to be so laborious and inaccurate that little data are collected. Root counts are used in soil surveys to evaluate root abundance; but these counts are not useful in most applications where data on roots are needed. An improved counting method provided root count data which correlated with measured root weight (AW = 0.97 PW, r2=0.85) where AW = actual weight and PW = predicted weight. Counts were made in a dm2 plexiglass frame parallel to the soil surface under short-and mid-grass prairie vegetation. As many as 30 samples were necessary to estimate root biomass within 25% (P<.10) with either root weighing or counting methods. Total root biomass calculated from root counts in the upper 100 cm of 15 southeastern Montana soils and in mine spoils ranged from 310 to 1,610 g/m2 which is similar to published data on root biomass in other grassland communities.
    • Sand Dams as a Feasible Water Development for Arid Regions

      Sivils, B. E.; Brock, J. H. (Society for Range Management, 1981-05-01)
      Water development is an important aspect of range improvement, particularly in arid regions. A structure including a masonry dam and a collection field of perforated pipes was covered with coarse gravel and capped with sand to develop a low evaporation water source at a remote location. Animals were permitted access to the collected water at a downstream trough. Following development, previously unused forages were utilized by livestock for the first time.
    • Sediment Production as Influenced by Livestock Grazing in the Texas Rolling Plains

      Wood, M. K.; Blackburn, W. H. (Society for Range Management, 1981-05-01)
      The influence of livestock on sediment production was evaluated on a Clay Flat range site with shrub canopy areas, and midgrass and shortgrass interspace areas in the Rolling Plains near Throckmorton, Texas. Sediment production in the shrub canopy areas was similar across grazing treatments of heavy and moderate stocking, continuous grazing; rested and grazed deferred-rotation; rested and grazed high intensity, low frequency (HILF); and two livestock exclosures which had not been grazed for 20 years. Sediment production from the shortgrass interspace area was similar for all grazing treatments except from the heavily stocked, continuously grazed pasture, where sediment production exceeded that of the rested HILF treatment. The midgrass interspace sediment production for the heavily stocked, continuously grazed treatment exceeded that of the deferred-rotation treatments and the exclosures. Likewise, sediment production for the grazed HILF treatment was greater than that for the rested deferred-rotation treatment and exclosure. Soil and vegetation variables which significantly influenced sediment production included aggregate stability, organic matter content, mulch, standing crop, bulk density, and ground cover.
    • The Binary Search for Accuracy in Plant Symbols

      Gibbens, R. P.; Bilan, T. N. (Society for Range Management, 1981-05-01)
      The transfer of data from field sheets to computer files always involves the risk of errors being made in plant symbols or other identifying codes. If a master list of symbols or codes is incorporated into the software programs used for data entry on CRT computer terminals the risk of making errors can be substantially reduced. This is done by utilizing the highly time efficient binary search to compare each entered symbol or code with the master list. Detection of errors before the data are transferred to computer files saves much time which would otherwise be spent in retrieving and correcting files.
    • Toxicity and Control of Kelsey Milkvetch

      Cronin, E. H.; Williams, M. C.; Olsen, J. D. (Society for Range Management, 1981-05-01)
      Kelsey milkvetch (Astragalus atropubescens Coult. and Fish.) contains miserotoxin (β-glucoside of 3-nitro-1-propanol). Chemical analyses and biological evaluations indicated moderately low concentrations of the toxin in this species. However, this plant has been implicated in cattle losses and a potential danger of both acute and chronic poisoning exists on grazing areas where kelsey milkvetch grows in abundance. It grows in mountainous areas in the Salmon River drainage in Idaho and the Big Hole River drainage in Montana. Kelsey milkvetch was controlled with an application of 2.24 kg/ha (2 lb/ac) of 2,4,5-T[2,4,5-tricholorophenoxy)acetic acid] and eradicated with an application of silvex [2-(2,4,5-tricholorophenoxy)propionic acid].
    • Translocation and Storage of 14 C-labled Total Nonstructural Carbohydrates in Honey Mesquite

      Fick, W. H.; Sosebee, R. E. (Society for Range Management, 1981-05-01)
      Translocation of total nonstructural carbohydrates (TNC) in mature honey mesquite (Prosopis glandulosa var. glandulosa) trees was studied by photosynthetically incorporating 14 CO2 on eight dates during the summer of 1975. Several plant parts were analyzed for TNC and relative total activity (RTA) to determine direction of translocation and sink strength. Stem and twig TNC fluctuated more than basal bud TNC in response to phenological development. Pods were generally the strongest TNC sink except during initial pod formation (June 25), when bidirectional translocation occurred and all plant parts sampled contained equal concentrations of the 14 C label. A RTA/TNC ratio used in conjunction with RTA and TNC suggested that increased TNC concentrations in the pods and stems may not always be due to increased import of TNC but caused by a reduction in growth with constant importation. Greatest translocation of TNC to the basal buds occurred between the phenological stages of green flower spikes (June 10) and pod formation (June 25) and during pod maturation (August 4 to August 19).
    • White-tailed Deer Diets from Pastures in Excellent and Poor Range Condition

      Bryant, F. C.; Taylor, C. A.; Merrill, L. B. (Society for Range Management, 1981-05-01)
      A study was initiated in August, 1975, to examine the forage available to and diet composition of white-tailed deer on pastures of excellent and poor range condition at the Sonora Research Station near Sonora, Texas. Grass and forb standing crop and deer feeding time on these two forage classes were considerably higher on the pasture in excellent range condition than that in poor range condition. Browse standing crop and feeding time was greater from the pasture in poor range condition. The Merrill 4-pasture grazing system appeared to increase the availability and use by deer of grass regrowth. Yearly averages of crude protein and phosphorus were higher in diet samples collected from the pasture in excellent range condition. Digestible energy levels were similar between pastures when averaged over the 1-year period. Digestible energy levels in diets were, however, higher from the excellent condition pasture in every season except winter. In winter, deer fed primarily on the foliage of oak on excellent condition range; but on the pasture in poor range condition, deer used large amounts of foliage and mast from juniper and dead leaves of persimmon in addition to oak foliage. Juniper and persimmon apparently contributed to the higher digestible energy levels observed on the pasture in poor range condition during the winter season. Energy may be a major nutrient limiting deer production on the Edwards Plateau.