• Establishment of Barbwire Russian Thistle in Desert Environments

      Evans, R. A.; Young, J. A. (Society for Range Management, 1980-05-01)
      Barbwire Russian thistle dominated a degraded plant community in the Carson Desert of northwestern Nevada and completely excluded Russian thistle in the course of the study. In seeding trials barbwire Russian thistle became established at low levels under arid conditions of the desert while Russian thistle failed to become established. Under semiarid conditions, seedling establishment of Russian thistle was five time greater than that of barbwire Russian thistle. Adaptations of barbwire Russian thistle that apparently favor seedling establishment under arid desert environments include earlier maturation and seed dispersal, seed dispersal beneath the parent plant, and less specific afterripening requirements than Russian thistle. These adaptations would permit germination and seedling establishment in the relatively wet periods of late winter and early spring in this arid ecosystem.
    • Frequency and Extent of Defoliation of Herbaceous Plants by Sheep in a Foothill Range Community in Northern Utah

      Hodgkinson, K. C. (Society for Range Management, 1980-05-01)
      Defoliation of individual plants by sheep grazing a shrub-steppe community in the foothill ranges of northern Utah was examined during a spring grazing. Five sites (each approx. 120 m2) within the paddock were monitored, and populations of one or more species (Aster chilensis, Wyethia amplexicaulis, Lupinus sericeus, Poa secunda, and Koeleria cristata) within these sites were examined daily for defoliation over a 25-day period. Grazing started at different times at each site, but once grazing started each site was visited daily. The proportion of the population of A. chilensis shoots that were grazed each day varied but was highest (about 30%) several days after grazing commenced at each site. Extent of defoliation of highly palatable species did not differ over time but did increase for W. amplexicaulis (forb of low palatability) at the end of the grazing period.
    • Grass, Trees, and Cattle on Clearcut-Logged Areas

      McLean, A.; Clark, M. B. (Society for Range Management, 1980-05-01)
      Generally, the presence of domestic grass had little effect on germination or survival of conifers on clearcut-logged areas, except where the stand of grass became overly dense. In cases where inhibiting effects were apparent, the competition from native vegetation was of as much consequence as the competition from domestic grasses. Results of the study suggest that where numbers of cattle and period of grazing were adequately controlled, damage to lodgepole pine and spruce seedlings were negligible. Damage was a result of repeated trampling rather than browsing. Poor cattle management in some situations resulted in overutilization of forage and large numbers of lodgepole pine seedlings were killed or damaged. However, the number was often insignificant in relation to the mortality of seedlings from natural causes. In a grazing trial the 4-year average daily weight gains were 0.64 kg for calves and 0.13 kg for their dams. Using the average weight gains and stocking rates, the pastures returned 60 kg of beef/ha/yr.
    • Impact of Incremental Surface Soil Depths on Infiltration Rates, Potential Sediment Losses, and Chemical Water Quality

      Lyons, S. M.; Gifford, G. F. (Society for Range Management, 1980-05-01)
      A study was conducted between October 1974 and August 1976 to measure the effects of incremented surface soil depths on infiltration rates, potential sediment production, and chemical quality of runoff water. The treatments were incremental removals of 7.6-cm soil layers to a depth of 30.5 cm on two pinyon-juniper sites in Utah. Hydrologic parameters were measured at each 7.6-cm incremental soil depth using a Rocky Mountain infiltrometer. With one exception, no significant differences occurred in infiltration rates among treatment depths during either 1975 or 1976 at either the Blanding (southeastern Utah) or Milford (southwestern Utah) site. A significant change in infiltration capacities was noted between the 1975 and 1976 field seasons when data from both treatment depths and study sites were pooled. There were no significant differences in potential sediment production between sites or among treatment depths at a site. In terms of chemical water quality, a significant change in phosphorus content of runoff waters was observed at the Blanding site between the 1975 and 1976 field seasons. Significant differences in potassium concentrations were found between sites and among soil depths. Nitrate concentrations were very low in runoff waters from all soil depths at both sites.
    • Impact of Incremental Surface Soil Depths on Plant Production, Transpiration Ratios, and Nitrogen Mineralization Rates

      Lyons, S. M.; Gifford, G. F. (Society for Range Management, 1980-05-01)
      From October 1974 to August 1976, a study was conducted to measure how incremental surface soil depths from the pinyon-juniper type affected plant production, plant transpiration rates, and nitrate nitrogen mineralization rates. The treatments were incremental removals of 7.6-cm soil layers to a depth of 30.5 cm. Plant production and transpiration ratios (or water use efficiencies) were measured in greenhouse studies using Agropyron desertorum grown in specified incremental 7.6-cm soil layers taken from five study sites throughout Utah. Significant decreases in plant production and increases in transpiration ratios were measured for all sites at incremental depths beyond 7.6-cm. These changes in plant production and transpiration ratios were linearly related to the nitrate nitrogen content of the soils (as determined when the soils were collected for use in the greenhouse). Nitrate mineralization rates were measured for two 6-week periods under field conditions at two sites for each of the 7.6-cm incremental soil layers. Nitrate nitrogen mineralization was linearly correlated with the organic carbon content of the soil. Decreased mineralization rates as measured in the field at both sites were reflected in the significant increases in plant water requirements and decreases in production that were measured in greenhouse studies.
    • Impact of Intensity and Season of Grazing on Carbohydrate Reserves of Perennial Ryegrass

      El Hassan, B.; Krueger, W. C. (Society for Range Management, 1980-05-01)
      Carbohydrate reserves of perennial ryegrass declined during winter and early spring and began replenishment during seed formation. The primary reserve accumulation in roots occurred during fall growth, while crowns replenished about half of their reserves from seed formation to fall and the balance during fall. Total nonstructural carbohydrate (TNC) reserves in roots were highest following a relatively wet year when compared to an average year but carbohydrate reserves were found to be more concentrated in the average year. Biomass of storage organs had a greater effect than concentration of carbohydrates on TNC reserves. Complete protection of perennial ryegrass from grazing did not induce greater accumulation of carbohydrate reserves when compared to any season of grazing treatment and they were sometimes significantly lower than for grazed treatments. No advantage from deferment of grazing in spring, summer, or fall could be determined based on carbohydrate reserves as along as stocking intensity did not exceed one ewe per 650 kg of herbage production per year. At stocking rates above this, deferment during part of the growing season should be beneficial.
    • Mineral Concentrations in True Mountain Mahogany and Utah Juniper, And In Associated Soils

      Brotherson, J. D.; Osayande, S. T. (Society for Range Management, 1980-05-01)
      Concentrations of minerals in soils and plants were measured in two communities. Zinc, copper, magnesium, phosphorus, and nitrogen showed significantly (p< 0.01) greater concentration in true mountain mahogany than in Utah juniper. Soils beneath plant canopies had significantly higher (p< 0.01) nitrogen than soils in open areas between plants. Concentrations of zinc, manganese, and phosphorus were significantly (p< 0.01) higher in the soils of the juniper community, while calcium and magnesium concentrations were significantly (p< 0.01) higher in the soils of the mountain mahogany community. True mountain mahogany showed copper concentration (x=28.9 ppm) high enough to approach toxic levels for some herbivores. Except for copper, mineral concentrations indicated good forage value for these two species.
    • Nitrogen Fixation (Acetylene Reduction) Associated with Rhizosheaths of Indian Ricegrass Used in Stabilization of the Slick Rock, Colorado Tailings Pile

      Wullstein, L. H. (Society for Range Management, 1980-05-01)
      Indian ricegrass sown on a sandy soil covering a uranium mine tailings exhibited associative nitrogen fixation (acetylene reduction). Acetylene reduction rates for whole plants varied from 2,100 to 19,500 nm/4 days. Nitrogen fixation was associated with the rhizosheaths. It is suggested that the reclamation of mine tailings in arid climates may be facilitated by stabilizing sandy textured coverings with rhizosheath-forming grasses.
    • Relationship of Distance Traveled with Diet and Weather for Hereford Heifers

      Ueckert, D. N.; Anderson, D. M.; Kothmann, M. M. (Society for Range Management, 1980-05-01)
      Distance traveled by Hereford heifers under continuous and high-intensity low-frequency (HILF) grazing was highly correlated with crude protein, digestible energy, forb content, and the ratio of grass leaf blade to stem plus leaf sheath obtained from diets collected via esophageal fistula. Observations confirmed that availability of palatable forbs was positively correlated with animal travel under HILF grazing management. Animal travel decreased under both management systems between July and December. Maximum diurnal temperatures and maximum diurnal water vapor, expressed as maximum mixing ratio, were significantly associated with travel under HILF grazing. Calculations indicated that the energy cost associated with horizontal travel for range cattle is greater than that allowed in the basal metabolism requirement set forth by the National Research Council.
    • Snow Trapping by Contour Furrows in Southeastern Montana

      Neff, E. L. (Society for Range Management, 1980-05-01)
      Contour furrows on fine-textured range sites in southeastern Montana caught an annual average of 22 mm more snow equivalent than nearby nonfurrowed areas. In addition, the furrows held snowmelt onsite in the spring and significantly reduced winter runoff in nearly half of the years of record. Except in years of much below normal winter precipitation, however, the winter runoff from furrowed areas was still more than adequate to fill well-designed stockponds.
    • Soil-Ingestion Rates of Steers Following Brush Management in Central Texas

      Kirby, D. R.; Suth, J. W. (Society for Range Management, 1980-05-01)
      Fecal soil concentrations and soil-ingestion rates were estimated for steers grazing pastures treated 1 year prior with herbicide or bulldozing and stacking. Mean fecal soil concentration was higher on mechanically treated, 16.6%, than those chemically treated, 12.5%, or untreated, 10.9%, under similar forage utilization levels (50%). With one exception, fecal soil concentration decreased over the study period on treated pastures. Fecal soil concentration was correlated with forb availability (r = 0.72) and percentage bare ground (r = 0.85) on treated pastures. At the forage utilization level of this study, no relationship between fecal soil concentration and stocking pressure was apparent.
    • Transforming a Traditional Forage/Livestock System to Improve Human Nutrition in Tropical Africa

      Sullivan, G. M.; Stokes, K. W.; Farris, D. E.; Nelsen, T. C.; Cartwright, T. C. (Society for Range Management, 1980-05-01)
      Livestock systems based on uncontrolled communal grazing result in inefficient utilization of native forages and low livestock production. Forage/livestock herd simulation models are adapted to Tanzania to evaluate a case of improved technology. A hay enterprise for lactating cows, not possible with uncontrolled communal grazing, was found to increase nutritional and monetary welfare of a typical village.