• The effects of intra-row spacings and cutting heights on the yields of Leucana leucocephala in Adana, Turkey

      Tuckel, Tuncay; Hatipoglu, Rustu (Society for Range Management, 1989-11-01)
      This research was conducted in Adana, Turkey, between 1985 and 1987. The study investigated the effects of the intra-row spacings and cutting heights on yields of 2 cultivars of Leucaena leucocephala, K8 and Peru. The trial was a split-split plot design in randomized blocks with 4 replications. The main plots were the cultivars, K8 and Peru; subplots were intra-row spacings, 25, 50, and 75 cm; and sub-sub plots were cutting heights, 20, 40, and 60 cm. Row spacing was 1m. Peru had higher leaf yields than K8. Increased intra-row spacing decreased both thin and thick dried stem yields and foliage yield per ha. The effects of cutting heights varied with the years. The highest dried foliage yield was obtained from the plots cut at 40 cm in the first year and 60 cm in the second year.
    • Test of Grazing Compensation and Optimization of Crested Wheatgrass Using a Simulation Model

      Olson, B. E.; Senft, R. L.; Richards, J. H. (Society for Range Management, 1989-11-01)
      We developed a simulation model based on tiller population processes to test grazing compensation and optimization in crested wheatgrass (Agropyron desertorum (Fisch. ex Link) Schult.). Model functions describing tiller dynamics and growth were derived from field observations in west-central Utah. Predicted tiller growth and new tiller production following defoliation were verified against additional data from the same site; total production was validated against a 30-year-old data set from a different site. We then simulated 2 grazing experiments. First, grazing compensation was determined as a function of the timing of a single defoliation during the growing season. Response variables included tiller density, plot growth rates, standing crop, and seasonal production. Second, grazing optimization, a combination of grazing frequency and intensity that increases primary production above that of ungrazed plants, was assessed by the systematic variation of these defoliation parameters under simulated dry, average, and wet winters (September-May). Results of the first experiment indicated that compensation depended mainly on the timing of defoliation, presumably because of phenological constraints to regrowth and the short growing season in this cold-desert region. Overcompensation only occurred when plants were defoliated before the traditional start of the grazing season. Although defoliation increased tiller growth rates, the second experiment failed to reveal an optimum combination of defoliation frequency and intensity resulting in maximum biomass production except after a dry winter. Results from the second experiment indicated that implementing intensive rotational grazing systems will seldom increase crested wheatgrass production in these cold-desert systems.
    • Technical Notes: Direct effect of parasitism by Dinarmus acutus Thomson on seed predation by Acanthoscelides perforatus (Horn) in Canada milkvetch

      Boe, A.; McDaniel, B.; Robbins, K. (Society for Range Management, 1989-11-01)
      Canada milk-vetch (Astragalus canadensis L.) is a widespread North American legume considered to be good forage in some regions but potentially dangerous to livestock when it contains high levels of 3-nitropropionic acid. Larvae of the seed predator Acanthoscelides perforatus (Horn) (Coleoptera:Bruchidae) occurred in 77% of the mature pods from 10 genotypes of the legume growing in a nursery at Brookings, S. Dak., in autumn 1987. Dinarmus acutus Thomson (Hymenoptera: Pteromalidae) parasitized 48% of the A. perforatus larvae and reduced numbers of seeds consumed by A. perforatus larvae by 23%. This study identified D. acutus as a parasitoid of A. perforatus and indicated parasitoids may play an important role in recruitment of native legumes.
    • Remote sensing technology for rangeland management applications

      Tueller, Paul T. (Society for Range Management, 1989-11-01)
      The future of rangeland resources development and management is dependent upon increased scientific capability. Remote sensing technology can contribute information for a variety of rangeland resource management applications. In future we can expect to see an increased number of professional range managers with expertise in remote sensing. This training will include, in addition to principles of aerial photo interpretation, digital image analysis technology, increased use of geographic information systems, airborne video remote sensing, and the use of newly developing high resolution systems. The data will be obtained from both aircraft and spacecraft. Applications will include inventory, evaluation, and monitoring of rangeland resources and the incorporation of remote sensing data to support and improve the decision processes on the use, development, and management of rangeland resource areas.
    • Predicting peak standing crop on annual range using weather variables

      George, Melvin R.; Williams, William A.; McDougald, Neil K.; Clawson, W. James; Murphy, Alfred H. (Society for Range Management, 1989-11-01)
      Wide yearly fluctuations in peak standing crop on California annual-type range are largely explained by temperature and precipitation patterns. The objective of this study is to improve the predictability of functions relating weather patterns and peak standing crop by including degree-days, dry periods, evaporation, season start dates, and lengths and precipitation as independent variables. Peak standing crop was regressed on these independent variables for the University of California Hopland Field Station (HFS) and San Joaquin Experimental Range (SJER). Fall and winter precipitation, winter degree-days, and longest winter dry period were related to peak standing crop at HFS (R2=0.61). Spring precipitation, growing season degree-days, winter evaporation, and winter and spring start dates were related to peak standing crop at SJER (R2=.72). The relationship of peak standing crop to accumulated precipitation on 20 November using 33 years of data (r2=0.34) was weaker than previously reported for the first 16 years (r2=0.49). This study suggests that timely prediction of peak standing crop may be possible at HFS but more difficult at SJER.
    • Motivation of Colorado ranchers with federal grazing allotments

      Bartlett, E. T.; Taylor, R. G.; McKean, J. R.; Hof, J. G. (Society for Range Management, 1989-11-01)
      Net returns to investment on western ranches are often low or negative. Ranchers who graze cattle on federal range during the summer in Colorado were sampled to determine their willingness to sell their ranches and to determine which factors were important in their decision to ranch. Cluster analysis was used to classify the ranchers into 4 groups. Willingness to sell the ranch was the most important factor in classifying groups. Approximately 75% of the federal permittees would not consider selling their ranches in the current market while over half responded that rate of return on investment was of little or no importance in their decision to be in the cattle business. The groups also differed with respect to the importance of being near family and friends, and labor and asset mobility.
    • Morphological and physiological variation among ecotypes of sweetvetch (Hedysarum boreale Nutt.)

      Johnson, D. A.; Ford, T. M. J.; Rumbaugh, M. D.; Richardson, B. Z. (Society for Range Management, 1989-11-01)
      This study considered seedling establishment characteristics, nitrogen fixation capability, nutritive value, and clustering relationships among 11 putative ecotypes of sweetvetch (Hedysarum boreale Nutt.). A total of 44 morphological and physiological variables were evaluated in greenhouse and field experiments. Sweetvetch root systems had large nodules that were capable of fixing nitrogen, a potentially useful attribute in the reclamation of nitrogen-limited environments such as mine spoils in the western United States. Sweetvetch provided forage during the spring and summer, but little forage was available during the fall and winter. An ecotype collected near Orem, Utah, exhibited superior seedling establishment characteristics under mesic conditions while an ecotype from near Duchesne, Utah, established well under xeric conditions. An ecotype from Hobble Creek, Utah, showed superior rhizome development, a potentially useful characteristic for stabilizing highly erodible areas. Although cluster analysis procedures indicated differences among the ecotypes, this clustering was not always clearly related to characteristics of the collection site. Sufficient genetic diversity was present among ecotypes to assure adaptation to a wide array of sites and to facilitate improvement through breeding and selection.
    • Herbivore effects on seeded alfalfa at four pinyon-juniper sites in central Utah

      Rosenstock, Steven S.; Stevens, Richards (Society for Range Management, 1989-11-01)
      Effects of rabbits (Lepus californicus, Sylvilagus spp.), mule deer (Odocoileus hemionus), and livestock on seeded alfalfa (Medicago sativa) were studied on 4 sites in central Utah. Sites were dominated by pinyon pine (Pinus edulis)-and Utah juniper (Juniperus osteosperma) and were doubled-chained and seeded with a mixture of grasses, forbs, and shrubs between 1959 and 1962. A 4-way exclosure was built on each site in 1962 which included the following treatments: (1) control (rabbits, deer, and livestock excluded), (2) rabbit access, (3) deer access, and (4) rabbit plus deer access. The fifth treatment (outside the exclosure) was accessible to rabbits, deer, and livestock. Alfalfa density and production were estimated at 1- to 5-year intervals between 1963 and 1986. Alfalfa growth form was measured in 1986. Stand densities declined from 0.5 to 8.5 plants/m2 to 0.5 to 2.5 plants/m2 during the 23-year sampling period. Reproduction by seed was not evident. Alfalfa production fluctuated greatly (4 kg/ha to 4,104 kg/ha) with precipitation and decreased with increased herbivore access. Treatment effects varied. Rabbits had a negative effect on alfalfa density at 2 sites, but no effect on alfalfa production. Deer use had inconsistent effects on alfalfa density, but reduced alfalfa production at 2 sites. The addition of livestock use reduced alfalfa density at 1 site, and alfalfa production at 3 sites. Grazing treatments had a marked effect on alfalfa growth form. Decreases in height and increases in basal cover were associated with increased herbivore access. Results of this study indicate that alfalfa can be an important and persistent component of seeding mixtures used on semiarid pinyon-juniper ranges.
    • Gambel oak root carbohydrate response to spring, summer, and fall prescribed burning

      Harrington, Michael G. (Society for Range Management, 1989-11-01)
      Control of Gambel oak (Quercus gambelii Nutt.) for increased forage production and conifer regeneration is difficult because of its vigorous sprouting ability. Nonstructural root carbohydrate concentrations, generally a good indicator of sprouting potential, were measured in understory Gambel oak in a dense ponderosa pine (Pinus ponderosa Laws.) stand following prescribed fire. Carbohydrates in roots of 1- to 2-year-old sprouts after a single fire treatment were similar to those in unburned, mature oaks. Two prescribed burns, 2 years apart during the summer carbohydrate depression, caused these root reserves to remain low into fall dormancy and probably contributed to an observed oak reduction. This summer carbohydrate depression, also observed in open-grown Gambel oak, can be recognized by rapid stem growth and new leaf production.
    • Emergence and root growth of three pregerminated cool-season grasses under salt and water stress

      Mueller, D. M.; Bowman, R. A. (Society for Range Management, 1989-11-01)
      Reclaiming salt-affected soils under semiarid conditions without irrigation is difficult. High salt concentrations both delay and decrease germination and emergence, which increases the time a soil must remain moist for germination and emergence to take place. Delayed germination can also affect a plant's capability to withstand summer drought because of limited root development. Cultural practices that encourage rapid growth at conditions suboptimal for germination should increase seedling emergence and reduce moisture requirements for emergence. We determined from greenhouse studies the effects of different levels of soil salinity and soil water on emergence and on root and shoot growth of 3 pregerminated cool-season grasses: 'Nordan' crested wheatgrass (Agropyron desertorum) (L.) Gaertn.), 'Flintlock' western wheatgrass (Pascopyrum smithii (Rydb.) A. Love), and 'Vinall' Russian wildrye (Psathyrostachys juncea (Fischer) Nevski). Seed pregerminated prior to sowing resulted in more rapid emergence than untreated seed for all species at all levels of soil salinity and soil water. Salinity and water stress delayed and/or reduced emergence more in the untreated than pregerminated seed of Russian wildrye and western wheatgrass. Pregerminating seed before planting also resulted in greater root biomass for all species and greater root lengths for the 2 wheatgrass species than did untreated seed.
    • Effects of stocking rate on quantity and quality of available forage in a southern mixed grass prairie

      Heitschmidt, Rodney K.; Dowhower, Steven L.; Pinchak, William E.; Canon, Stephen K. (Society for Range Management, 1989-11-01)
      The objective of this study was to quantify the long-term (25 years) effects of heavy (HC) and moderate (MC) rates of stocking on quantity and quality of forage available. Study design required frequent harvest of standing crop on 5 range sites in twice replicated, 244 ha treatment pastures. Results from the 20-month study showed aboveground standing crop dynamics were similar in both treatments, quantity of available forage was greater in the MC than HC treatment, quality of available forage was greater generally in the HC than MC treatment, and that heavy stocking favored a dominance of warm-season shortgrasses as opposed to a dominance of warm-season midgrasses. Averaged across dates and adjusted for differences among pastures in range site composition, aboveground herbaceous standing crop averaged 1,341 kg/ha in the HC pastures as compared to 1,816 kg/ha in the MC treatment pastures. Crude protein and organic matter digestibility averaged 8.6% and 49.3%, respectively, in the HC pastures and 7.7% and 46.7%, respectively, in the MC pastures. It is concluded that the greater variation among years in cow/calf production in the HC than in the MC treatment is primarily because forage availability in the HC treatment is less than in the MC treatment.
    • Diet and forage quality of intermediate wheatgrass managed under continuous and short-duration grazing

      Nelson, M. L.; Finley, J. W.; Scarnecchia, D. L.; Paris, S. M. (Society for Range Management, 1989-11-01)
      Diet quality and forage quality were determined under short-duration and continuous grazing of intermediate wheatgrass (Agropyron intermedium) in 72-day grazing trials in 1985 and 1986. The short-duration unit was divided into 8 subunits grazed sequentially for 3 days each. Six crossbred heifers and 2 esophageally fistulated steers were randomly assigned to each grazing treatment. Animals were weighed and fecal samples, pasture samples, and diet (esophageal masticate) samples were collected in each of the three 24-day periods. In vitro organic matter disappearance (IVOMD) of steer diets under short-duration grazing declined linearly across periods of both years and across days within periods in 1986. Crude protein content of steer diets under short-duration grazing declined quadratically across periods in 1986. Crude protein and IVOMD content of steer diets under continuous grazing declined linearly in 1985. The effects of 4 maturities of intermediate wheatgrass on digestibility and ruminal kinetics were compared in a 4 × 4 Latin square design with 4 ruminally and abomasally fistulated crossbred wethers. Organic matter intake and digestibility, in situ rate and extent of NDF digestion, liquid passage rate and particulate mass flowing from the rumen decreased linearly with increased forage maturity. These data suggested that effects of forage maturity or period of grazing had similar effects on diet quality and forage quality. However, diet quality under short-duration grazing also declined across days within subunits.
    • Association of relative food availabilities and locations by cattle

      Bailey, D. W.; Rittenhouse, L. R.; Hart, R. H.; Swift, D. M.; Richards, R. W. (Society for Range Management, 1989-11-01)
      Four yearling steers were trained and observed in a parallel-arm maze. The purpose was to determine if cattle had the ability to associate locations with relative food availabilities. The study consisted of 3 phases. In phase 1, all 5 arms contained 0.4 kg of grain. In phase 2, the amount of grain in each arm was systematically varied from 0.1 to 0.8 kg. In phase 3, placement of grain was reversed. Steers performed efficiently in all 3 phases of the study. The overall-mean number of correct choices in the first 5 entrances was 4.69 as compared to 3.73 by chance. Arms selected for choices 2, 3, and 4 during the last 5 trials of phase 2 were different (P<0.05) from those selected during the last 5 trials of phase 3. For the last 5 trials of phases of 2 and 3, arms selected in choices 1, 2, and 3 contained 0.4, 0.6 and 0.8 kg of grain on 85% of the trials. Steers appeared to order their choices from larger to smaller rewards. Steers apparently can remember not only where they have foraged, but also the amount of food found there.