• A seed midge pest of big bluestem

      Carter, M. R.; Manglitz, G. R.; Rethwisch, M. D.; Vogel, K. P. (Society for Range Management, 1988-05-01)
      A Cecidomyiid midge reared from the panicles of big bluestem (Andropogon gerardii Vitman (var. gerardii) at Mead, Neb., was identified as Contarinia wattsi Gagné. This midge was previously known only from panicles of little bluestem (Schizachyrium scoparium (Michx.) Nash) in New Mexico. In Nebraska, C. wattsi appears to have a minimum of 3 generations per season. Larvae of the earlier generations leave the florets after completing development, making it difficult to associate floret damage with the midge. Larvae of the last generation of a season remain in diapause, in the floret, throughout the winter. Evidence obtained in this study in 1985 indicates that, at harvest time, 7 and 15% of the florets in the 2 fields studied contained diapausing midges. However, when an estimate of seed loss by the earlier generations (as indicated by empty florets and small seed) was considered, the total loss was probably closer to 40%. An unidentified species of thrips (Thysanoptera: Thripidae) also was found in big bluestem florets during this study. However, evidence suggests that thrips do not damage big bluestem seed as seriously as the midge.
    • An inexpensive alternative esophageal cannula for growing steers and wethers

      Nelson, M. L. (Society for Range Management, 1988-05-01)
      A method for manufacturing esophageal cannulas from plastic tee couplers of suitable size for growing steers and wethers is described.
    • Breed comparisons and characteristics of use of livestock guarding dogs

      Green, J. S.; Woodruff, R. A. (Society for Range Management, 1988-05-01)
      Research has shown that dogs can protect livestock from coyotes (Canis latrans), but information is lacking on comparative effectiveness of dog breeds and on how successfully dogs are being used by livestock producers. We mailed questionnaires to 948 livestock producers in the U.S. and Canada who were likely to be users of livestock guarding dogs. Three hundred ninety-nine written responses were received reporting data on 763 dogs, almost all recognized guarding breeds. Respondents were livestock producers from 47 states and 7 provinces. Producers rated their dogs as very effective (71%), somewhat effective (21%), or not effective (8%) in deterring predation; the majority (82%) said dogs were an economic asset. No particular breed was rated more highly, and the rate of success between males and females was not different. Fifty nonrespondents were telephoned, and although fewer of them had dogs than respondents, their rating of the dogs they used was not significantly different from that of respondents. The data indicate that, when used by producers, livestock guarding dogs are an effective method to manage predation.
    • Changes in grass basal area and forb densities over a 64-year period on grassland types of the Jornada Experimental Range

      Gibbens, R. P.; Beck, R. F. (Society for Range Management, 1988-05-01)
      Between 1915 and 1932, permanent 1 × 1-m quadrats were established on grasslands of the Jornada Experimental Range in southern New Mexico. Quadrat records accumulated from 1915 to 1979 on grasslands dominated by black grama [Bouteloua eriopoda (Torr.) Torr.], poverty threeawn (Aristida divaricata Willd.), tobosa [Hilaria mutica (Buckl.) Benth.], and burrograss (Scleropogon brevifolius Phil.) were used to examine changes in perennial grass basal area and forb densities. Quadrats originally dominated by black grama had large reductions in basal area during droughts, and basal area increased slowly following droughts. By 1979, black grama no longer occurred on 77% of the quadrats. Quadrats originally dominated by poverty threeawn changed to a mesquite (Prosopis glandulosa Torr. var. glandulosa) type. Perennial grass basal area on quadrats dominated by tobosa and burrograss decreased during droughts, but recovery was relatively rapid. Antecedent precipitation was associated with only 10 to 38% of the variation in perennial grass basal area. Perennial forb densities were low and fluctuated among years in all types. Annual forbs and grasses displayed large fluctuations in densities among years. The necessity of basing management of Chihuahuan Desert ranges on the perennial grass component is borne out by the low densities of palatable perennial forbs, and the extreme fluctuation and unpredictability in densities of annual forbs and grasses.
    • Correlation of degree-days with annual herbage yields and livestock gains

      George, M. R.; Raguse, C. A.; Clawson, W. J.; Wilson, C. B.; Willoughby, R. L.; McDougald, N. K.; Duncan, D. A.; Murphy, A. H. (Society for Range Management, 1988-05-01)
      On California's winter annual rangelands precipitation controls the beginning and end of the growing season while temperature largely controls seasonal growth rates within the growing season. Post-germination accumulated degree-days (ADD) account for the length of the growing season and variation of daily temperature. Simple correlations of ADD and herbage yield or resultant livestock gains were determined at 5 locations in annual type range in northern California. Degree day values were determined by summing daily degree-days from the beginning of the growing season after germinating rainfall until the clipping or weigh dates. Accumulated degree-days accounted for 74 to 91% of the variation in seasonal herbage yield while accumulated days (AD) accounted for 64 to 86% of the variation. Together, ADD and AD accounted for 94 and 86%, respectively, of the variation in stocker cattle weights. Regression coefficients relating ADD to herbage yield appear to predict maximum site productivity. A procedure for estimating a seasonal herbage yield profile based on key growth curve inflection points and using simple field observations with 3 clipping dates and ADD is proposed.
    • Effect of burning on seed production of bluebunch wheatgrass, Idaho fescue, and Columbia needlegrass

      Patton, B. D.; Hironaka, M.; Bunting, S. C. (Society for Range Management, 1988-05-01)
      A study was conducted in 1984 to determine the effect of fall prescribed burning on seed production of bluebunch wheatgrass (Agropyron spicatum), Idaho fescue (Festuca idahoensis), and Columbia needlegrass (Stipa columbiana) in the sagebrush (Artemisia spp.)/grassland region. Plots were located on 7 burns of ages 1 to 5 years, with plots in adjacent unburned areas serving as controls. Seed production (seeds per plant) of bluebunch wheatgrass was greater on 2 of four 1-year-old burns and on one 3-year-old burn than on unburned comparison areas. Idaho fescue seed production was greater on a 5-year old burn than on the control plot, but not statistically different from the controls on 1- or 3-year-old burns. Columbia needlegrass seed production was markedly greater on a 2-year-old burn than on adjacent unburned areas. The percentage of filled florets and the number of seeds per inflorescence tended to be greater on burned plots for all 3 species. Bluebunch wheatgrass showed a variable response in the number of inflorescences produced per plant 1 year after burning, but there were significantly (P is lesser than or equal to 0.05) more inflorescences per plant on the 3-year-old burn than the control. Idaho fescue plants produced fewer inflorescences on both 1-year-old burns than on the control plots, but more on the 5-year-old burn than on the control. Columbia needlegrass plants produced more inflorescences on the burn than on the control.
    • Effect of defoliation frequency and N-P-K fertilization on maidencane

      Kalmbacher, R. S.; Martin, F. G. (Society for Range Management, 1988-05-01)
      Maidencane (Panicum hemitomon Schult.), an important grass on Florida and southeastern Gulf Coast fresh-water marsh range, was cut on 3-, 6-, 9-, 12- and 24-week intervals (T) from June to December 1982 and 1983. Half the plots were fertilized every 6 weeks with 56, 12, and 22 kg/ha N, P, and K, respectively. Dry matter yield (DM), tiller density (TD), rhizome total nonstructural carbohydrate (TNC), crude protein (CP), and in vitro organic matter digestibility (IVOMD) were determined. DM was reduced with frequent clipping, especially every 3 weeks, and 2-year average DM was described: 1981 + 660T -22T2, where T is weeks between harvest. Fertilized grass yielded more DM (6,270 kg/ha) than unfertilized (4,410). TD increased as harvest interval increased. For example TD in April 1983 was TD = 40 + 19.1T. TNC was affected by cutting interval (7.2 + 0.61T - $0.016T2) but not fertilization. CP and IVOMD declined about 0.5 and 3.0 units, respectively, for each week forage remained on range. Fertilization improved 2-year average CP (yes = 13.3%, no = 11.9%), but IVOMD was unaffected. Defoliation of maidencane every 3 to 6 weeks reduced stands and yield, and defoliation intervals longer than 3 to 6 weeks resulted in reduced protein and digestibility. Fertilizer rates and timing of application used in this study did help to maintain yield and tiller density at a higher level than unfertilized grass in the second year.
    • Effects of temperature, water potential, and sodium chloride on Indiangrass germination

      Fulbright, T. E. (Society for Range Management, 1988-05-01)
      Indiangrass [Sorghastrum nutans (L.) Nash] is widely used in range seeding. Objectives of this study were to determine the effects of temperature, water potential, and sodium chloride on germination of 'Lometa', 'Cheyenne', 'Llano', 'Oto', and 'Tejas' Indiangrass. Seeds were germinated at 6 alternating temperatures ranging from 5-15 to 30-40 degrees C (12 hours-12 hours). Lometa, Cheyenne, and Tejas seeds were germinated in polyethylene glycol (mol. wt. = 8,000) solutions mixed to approximate water potentials of 0, -0.4, -0.8, -1.2, and -1.6 MPa and in 0, 0.06, 0.12, 0.18, and 0.24 mol liter-1 sodium chloride solutions. Optimum temperatures for percent germination were 10-20 to 25-35, 10-20 to 20-30, and 15-25 and 20-30 degrees C for Cheyenne and Tejas, Llano and Oto, and Lometa seeds, respectively. Percent germination of Cheyenne and Lometa seeds was reduced at water potentials of -0.8 MPa and lower, while Tejas seeds exhibited lower percent germination than controls at -1.2 and -1.8 MPa. Percent germination of Cheyenne and Lometa seeds was reduced by sodium chloride concentrations of 0.12 mol liter-1 and greater. Germination of Tejas seeds was reduced at 0.18 and 0.24 mol liter-1. Indiangrass varieties appear to germinate within a similar range of temperatures but vary in germination response to low water potentials.
    • Electric fences for reducing sheep losses to predators

      Nass, R. D.; Theade, J. (Society for Range Management, 1988-05-01)
      The use of anti-predator electric fences for reducing predation on sheep was investigated by interviewing 101 sheep producers in the Pacific Northwest. Significant reductions in sheep losses to predators were reported after installation of electric fences compared to pre-fence losses. Low sheep losses to predation were also reported by those producers that acquired sheep after installation of electric fences. The expenses of construction and maintenance were important considerations in management plans; however, most producers were satisfied with electric fences for sheep containment and predator exclusion.
    • Estimating digestibility of oak browse diets for goats by in vitro techniques

      Nastis, A. S.; Malechek, J. C. (Society for Range Management, 1988-05-01)
      Predicting digestibility of shrubs is important to evaluating many of the world's rangelands. We examined laboratory procedures for predicting in vivo digestion of browse-alfalfa (Medicago sativa) mixed diets and how drying temperature and inoculum source affect digestibility. In addition, we considered the effect of oak tannin on pepsin activity and dry matter digestion. The commonly used Tilley and Terry (1963) two-stage in vitro digestion technique was a precise (r2=0.97) but inaccurate predictor of in vivo apparent digestibility of mixed oak (Quercus gambelii) and alfalfa diets for goats. The Van Soest et al. (1966) neutral detergent method for predicting true digestibility was less precise (r2=0.76). Estimates from the Goering and Van Soest (1970) summative equation were not correlated (P is lesser than or equal to 0.05) with in vivo digestion. Separate regression equations are necessary if in vitro methods are to predict accurately in vivo digestibility of browse diets. In vitro digestibility was inversely related to percentage of oak in the diets and the amount of oak in the inoculum donors' diets. High drying temperatures depressed digestibility of oak browse and this effect was greater for immature than for mature forage.
    • Factors influencing infiltrability of semiarid mountain slopes

      Wilcox, B. P.; Wood, M. K.; Tromble, J. M. (Society for Range Management, 1988-05-01)
      The objective of this research was to determine the effects of selected vegetation, soil, rock, and slope variables on infiltration of semiarid rangelands with slope gradients ranging from 0-70%. Analyses were made on 2 sets of data collected a year apart in the Guadalupe Mountains of New Mexico and consisted of Pearson and partial correlation analysis of the dependent infiltration variables and independent site variables. In addition, infiltration was regressed against uncorrelated factors produced by factor analysis. Vegetal cover and biomass strongly influenced infiltration. The relative importance of grasses, shrubs or litter was dependent on their respective abundance, especially grass. Soil depth also limited infiltration especially as soil water storage became satisfied. Infiltrability was negatively correlated with rock cover and the smallest rock size fragments were the most negatively related. When the effects of vegetal cover and slope were removed (using partial correlation analysis) however, the median sized rock fragments (26-150 mm) were positively related to infiltrability, and the smallest rock fragements (2-12 mm) were negatively related. Partial correlation analysis also suggested a positive correlation between infiltrability and slope gradient.
    • Growth and gas exchange of Andropogon gerardii as influenced by burning

      Svejcar, T. J.; Browning, J. A. (Society for Range Management, 1988-05-01)
      Late spring burning response of the dominant big bluestem (Andropogon gerardii) was studied on a tallgrass site in central Oklahoma (USA) during a dry (1984) and a wet (1985) year. During active growth (May and June) when temperatures were not limiting, photosynthesis (PS) was higher for burned (25-27 micromoles-2-1) relative to unburned plants (20-25 micromoles m-2 s-1); but during summer drought, PS declined to <10 micromoles m-2 s-1 and treatment rank reversed. However, the 2 treatments had similar transpiration per unit leaf area, and burned plots had much higher peak big bluestem leaf area indices (6.4 in 1984 and 4.5 in 1985) than unburned plots (2.0 both years). Apparently higher transpirational demand in burned plots lowered soil moisture, thereby increasing late season moisture stress and lowering PS relative to unburned plots. Burning resulted in a doubling of big bluestem tiller numbers (997-1,034 and 498-600 tillers m-2 for burned and unburned plots, respectively). Peak aboveground biomass of big bluestem was about 3 times higher on burned relative to unburned prairie during both years. During both years burned vs. unburned big bluestem had higher peak values of % leaf nitrogen (N) and more total leaf N (%N* leaf mass). Thus, burning big bluestem increased leaf area during the active growth period and stimulated PS, resulting in higher carbon uptake of burned relative to unburned plants.
    • Heifer nutrition and growth on short duration grazed crested wheatgrass

      Olson, K. C.; Malechek, J. C. (Society for Range Management, 1988-05-01)
      Animal performance and nutrition under short duration grazing (SDG) and season-long grazing (SLG) were compared on spring-grazed crested wheatgrass [Agropyron desertorum (Fisch.) Schult. and A. cristatum (L.) Gaertn.] range to determine if SDG has the potential to improve livestock production on such rangelands. Livestock performance was evaluated by measuring weight gains twice per grazing season. Diet quality was assessed by determining crude protein concentration and in vitro organic matter digestibility of extrusa samples collected from esophageally fistulated heifers. Three variables of ingestive behavior were measured: ingestion rate, biting rate, and grazing time. Daily forage intake was calculated as the product of ingestion rate and grazing time. Animals in the SLG treatment gained significantly more than those under SDG in 1983 (1.07 vs. 0.81 kg/hd/d), but no statistical differences were detected in 1984 (1.13 vs. 1.07 kg/hd/d for SDG and SLG, respectively). In 1985, animals under SDG gained the most (1.03 vs. 0.87 kg/hd/d for SDG vs. SLG, respectively). No differences were detected in diet quality between SDG and SLG throughout the study. No treatment differences were detected in ingestive behavior during 1984, but ingestion rate was greater and grazing time less under SDG than SLG during 1985. Results indicate that forage intake was greater, while energy expenditures were lower under SDG than SLG in 1985. The hypothesis that SDG extends the season of nutritious forage was not supported.
    • Herbage dynamics of tallgrass prairie under short duration grazing

      Brummer, J. E.; Gillen, R. L.; McCollum, F. T. (Society for Range Management, 1988-05-01)
      Simulated 8-pasture short duration grazing systems were studied in 1985-86 to determine the effect of timing and intensity of grazing on seasonal herbage dynamics. Treatments consisted of 3 grazing schedules (2, 3, or 4 rotation cycles per 152 day grazing season) and 2 stocking rates (1.3X and 1.8X the recommended normal). Average seasonal standing crop increased from 4-cycle to 2-cycle grazing at the light stocking rate but did not respond to grazing schedule at the heavy stocking rate. Within the grazing season, herbage standing crop was affected by grazing schedule in late summer in 1985 but not in 1986. Favorable growing conditions resulted in light forage utilization which averaged 30% over all treatments. Net herbage accumulation rates were not affected by any experimental factor and averaged 34 kg ha-1 d-1 over all treatments. Time trends for net herbage accumulation rate from May to September were also similar across treatments. Total herbage disappearance and herbage disappearance per animal-unit-day (AUD) were significantly higher under 4-cycle grazing at the heavier stocking rate than under all other treatments.
    • Irrigation water for vegetation establishment

      Ries, R. E.; Sandoval, F. M.; Power, J. F. (Society for Range Management, 1988-05-01)
      This research project was conducted to evaluate the use of irrigation water to supplement precipitation during establishment of perennial forage plant communities on surface mined lands in the northern Great Plains. The treatments included precipitation and 9 combinations of various quantities of medium and low quality water applied to a clay loam topsoil replaced over a loam minespoil. We measured the response to the added water of a seeded forage species mixture, volunteer weeds, and changes in salinity and sodicity of the soil/spoil profile. All levels of irrigation, regardless of water quality, increased seeded species production, but decreased weed dry matter. One season of irrigation with medium or low quality water produced minimal changes in soil salinity and sodicity. Some increase in soil salinity and sodicity was observed when low quality water was added during the second season. Therefore, low quality water can be used beneficially to supplement precipitation for 1 or 2 seasons during the establishment of perennial plant communities on moderately permeable soil/spoil areas.
    • Levels of a neurotoxic alkaloid in a species of low larkspur

      Majak, W.; Engelsjord, M. (Society for Range Management, 1988-05-01)
      A survey of the levels of the neurotoxic diterpenoid alkaloid methyllycaconitine (MLA) in low larkspur (Delphinium nuttallianum Pritz.) was conducted at 4 diverse rangeland sites in southern British Columbia. Freeze-dried plant samples representing 3 stages of growth over 2 growing seasons were analyzed for MLA by high pressure liquid chromatography. Significant differences were found among experimental sites (P<0.001) with higher levels of MLA (>0.2% on a dry weight basis) being associated with sites at higher elevations (900-975 m). At one site, an exceptional level of MLA (>0.3%) was observed during the flower bud stage of growth but in general the alkaloid levels remained fairly constant with advancing stages of growth. Measurement of the MLA concentrations in different plant parts revealed that reproductive parts contained higher levels of MLA than vegetative parts and this may well explain the increased toxicity of the upper portions of the plant.
    • Mechanical shrub control on flatwoods range in south Florida

      Tanner, G. W.; Wood, J. M.; Kalmbacher, R. S.; Martin, F. G. (Society for Range Management, 1988-05-01)
      Relative plant abundance, canopy cover, and aerial biomass of shrubs on a poor condition, flatwoods range in south Florida were measured before, 1, and 3 yr after a single pass of a roller chopper or web plow when soils were dry (May 1981) and when soils were saturated (September 1981). Aerial biomass of herbaceous species was measured at the post-treatment sample dates. Abundance of saw-palmetto (Serenoa repens (Bartr.) Small) plants, the dominant shrub, was reduced 70% by web plowing compared to 25% by roller chopping. Reduction of saw-palmetto canopy cover and aerial biomass also were greater on web-plowed than on roller-chopped plots. Runner oak (Quercus minima (Sarg.) Small) was the only other shrub which had more than 5% canopy cover before treatment. Both types of mechanical treatments controlled runner oak by approximately 50%. However, responses of runner oak abundance, canopy cover, and aerial biomass were not significantly different between roller chop and web plow treatments.
    • Planting depth and soil texture effects on emergence and production of three alkali sacaton accessions

      De Alba-Avila, A.; Cox, J. R. (Society for Range Management, 1988-05-01)
      Pure stands of alkali sacaton (Sporobolus airoides) once grew on playas and lowland alluvial flood plains, as well as on surrounding hills and terraces in semiarid areas of North America. Stands have all but disappeared on hills and terraces in the past 100 years. The purpose of this research was to evaluate the establishment and initial production characteristics of 3 alkali sacaton accessions when seeds were sown at various depths in 3 soils where soluble salts and exchangeable sodium do not accumulate. 'Saltalk', 'NM-184' and 'DU-82' accessions were sown at 5 depths in Pima finesilty, Sonoita coarse-loam, and Comoro coarse-loam soils in a greenhouse. Seedling emergence from seed sown at 5 mm was greater than for seed sown at 0, 10, 15, and 20 mm in Comoro (sandy), but was equal at all depths in the cracking Pima soil. Above- and below-ground biomass were greatest in Comoro, intermediate in Pima, and lowest in Sonoita soils, but differences were not always significant. The 3 accessions responded similarly to planting depth within a soil, although initial emergence counts indicate differences among accessions.
    • Root systems of two Patagonian shrubs: A quantitative description using a geometrical method

      A, R. J. F.; Paruelo, J. M. (Society for Range Management, 1988-05-01)
      A method for mapping coarse root distribution suitable for stony soils was developed. Each root is considered as a broken line, whose segments are fairly straight root portions. The spatial location of end points of these segments is recorded in the field through 3 coordinates: its distance from plant vertical axis, its depth, and its distance to the foregoing point on the same root. With these data the roots' spatial arrangement is reproduced using a computer program including simple geometrical relationships. The main advantages of the method are: (a) it does not require sample harvesting and handling; (b) it considers root length instead of root biomass; and (c) its quantitative character allows statistically valid comparisons. Two species living in the Patagonian semidesert were studied: neneo (Mulinum spinosum, Umbeliferae) and mata mora (Senecio filaginoides, Compositae). In both shrubs, roots extend laterally more than 2 m and root length decreases exponentially as the distance from the canopy edge increases. Neneo was found to have its maximal root density at a depth of 0.4 m, whereas mata mora has most of its roots close to the soil surface. An interpretation of the differential response of these shrubs to grazing derives from these results.