• Use of stochastically generated weather records with rangeland simulation models

      Wight, J. R.; Hanson, C. L. (Society for Range Management, 1991-05-01)
      We compared long-term historical and stochastically generated weather records in terms of their statistical attributes and effects on herbage yield and runoff forecasts calculated from model simulations. The historical and synthetic air temperature and solar radiation records were in good agreement in terms of monthly means and extremes. The synthetic precipitation record failed to simulate extreme precipitation events which significantly reduced forecasted runoff values. Yield forecasts were similar using either historical or synthetic weather records.
    • The effect of hormone, dehulling and seedbed treatments on germination and adventitious root formation in blue grama

      Roohi, R.; Jameson, D. A. (Society for Range Management, 1991-05-01)
      Under usual range conditions, the time between blue grama (Bouteloua gracilis) germination and adventitious roots development is such that it is rare that both of these events occur with moist soil conditions, and seedling survival is infrequent. Establishment could be enhanced if the time between germination and adventitious root development were reduced. Dehulling followed by pretreatment of seeds with selected hormones such as indoleacetic acid reduced the time between these 2 events, and may increase the probability of successful seeding. These treatments also increased the length and number of adventitious roots during early stages of development. Water injection into the planting rows at seeding time added to the beneficial effects of seed treatment, while chemical mulching detracted from these responses.
    • Technical Notes: Evaluation of dietary preference with a multiple latin square design

      Borman, M. M.; Adams, D. C.; Knapp, B. W.; Haferkamp, M. R. (Society for Range Management, 1991-05-01)
      A sequential multiple latin square experimental design was evaluated as a tool for establishing dietary preference rankings. Dietary preference of 4 grasses was determined by a series of four 4 X 4 latin squares where rows were 4 days within a pen, columns were 4 locations of a grass within a pen, and treatments were 4 grasses. Each square (i.e., pen) utilized 1 lamb. Following the completion of trial 1, the most preferred grass was withdrawn and the 3 remaining grasses were further studied with a series of four 3 X 3 latin squares. This procedure was found to be a resource efficient and effective tool for preference ranking.
    • Selecting Atriplex canescens for greater tolerance to competition

      Ueckert, D. N.; Petersen, J. L. (Society for Range Management, 1991-05-01)
      Success in establishing fourwing saltbush [Atriplex canescens (Pursh) Nutt.] is often limited by competition from associated vegetation. Fourwing saltbush is reported to have abundant natural genetic variation, hence selection for plant vigor or competitiveness may be an effective tool for cultivar improvement. We observed distinctive within-accession variation in the apparent ability of fourwing saltbush seedlings to tolerate competition from sideoats grama [Bouteloua curtipendula (Michx.) Torr.] in a 1982 field planting. Superior and inferior parental saltbush phenotypes in the field planting were cloned in 1984 by rooting stem cuttings, and the cloned propagules were transplanted into plots with or without competition to test the hypothesis that the competitiveness trait was genetically controlled. Survival and canopy development of superior and inferior clones planted at the same time in competition regimens were similar, suggesting that the parental phenotypes were not genetically different in their ability to tolerate competition. Differences observed in the parental phenotypes may have been environmentally induced, or genetic differences in the clonal material may have been masked by using rooted cuttings rather than seedlings, by excessive competitive pressure in the competition regimens utilized, or both. Clones from the 2 parental phenotypes performed similarly when transplanted into competition-free regimens in November when growing conditions were favorable, but canopy development of clones from superior parental phenotypes exceeded that of those from inferior parental phenotypes when transplanted into competition-free regimens in April when growing conditions were poor.
    • Research Note: A survey of current range research activity

      Hardesty, L. H. (Society for Range Management, 1991-05-01)
      Range scientist members of the Society for Range Management were surveyed to evaluate where research efforts have been concentrated in the recent past relative to current and future allocation of efforts, how research is funded, where it is published, how well the scientists perceive that clientele needs are met, and what obstacles scientists face. Range ecology and range improvements are the topics that were, and continue to be seen as the most important for investigation. Plant improvement, range watershed, range wildlife, and ecophysiology are important future research topics. In-house funding was the most frequent source of funds for all groups of range researchers. University scientists were the most likely to have other sources of funds. There are funding sources that may be underutilized. The 4 most frequently listed clients are livestock producers (73 listings), state and federal agencies (71), other scientists (46), and the private sector (27). Forest Service scientists appear to have the least restricted view of their clientele. Over 25% of the respondents felt that there were no client groups not being adequately served by range research. Others felt that livestock producers and the public were not being adequately served. The Journal of Range Management was the most frequently listed publication outlet followed by conference papers and symposium proceedings. Limited funding was the most frequently listed obstacle to doing research, followed by poor communication between researchers and clients, and the need for more interdisciplinary interaction.
    • Rangeland experiments to parameterize the water erosion prediction project model: vegetation canopy cover effects

      Simanton, J. R.; Weltz, M. A.; Larsen, H. D. (Society for Range Management, 1991-05-01)
      The Water Erosion Prediction Project (WEPP) is a new water erosion prediction technology being developed by the USDA-Agricultural Research Service to replace the Universal Soil Loss Equation. Rangeland field experiments were designed to parameterize the WEPP rangeland erosion model. Included in the field experiments were plot treatments designed to separate direct from indirect effects of vegetation canopy on runoff and soil erosion. Nine rangeland sites from a wide range of soil and vegetation types were evaluated using rainfall simulation techniques. Natural versus clipped treatment surface characteristics and runoff and erosion responses were compared using regression analyses. These analyses showed that there were no significant differences between natural and clipped plot surface characteristics, runoff ratios, final infiltration rates, or initial rainfall abstractions. Erosion rates were different between treatments with the clipped plots having slightly less erosion than the natural plots. Results indicated that, under the rainfall conditions simulated, canopy cover was not directly contributing to initial abstractions through rainfall interception loss or significantly affecting runoff or erosion.
    • Monitoring roots of grazed rangeland vegetation with the root periscope/mini-rhizotron technique

      Karl, M. G.; Doescher, P. S. (Society for Range Management, 1991-05-01)
      The root periscope/mini-rhizotron technique has been used most commonly to monitor root growth of field crops in a nondestructive manner. This study introduces a successful application of the technique for monitoring root growth of grazed rangeland vegetation. The relative, root growth response of orchardgrass (Dactylis glomerata L. 'Potomac') to defoliation by cattle was monitored on a conifer plantation in southwest Oregon. Despite stocking densities of about 2.7-4.4 animal unit/ha and 19 days of grazing during 1988, trampling and breakage of mini-rhizotrons on the cattle-grazed area was minimal. Defoliation by cattle had a negative impact on the relative number of roots for grazed orchardgrass in June and July (P < 0.05). Cautions and limitations for the use of the technique on rangelands are presented. The root periscope/mini-rhizotron appears to be a suitable, nondestructive, and affordable (1,000-1,200 per root periscope; 8.50 per mini-rhizotron) technique for monitoring root growth of rangeland vegetation defoliated by livestock and/or native ungulates.
    • Managing range cattle for risk—the STEERISK spreadsheet

      Hart, R. H. (Society for Range Management, 1991-05-01)
      Variable weather, forage production, weed and pest problems, and livestock prices contribute to uncertainty in range livestock production. Because returns from livestock production, in which producers invest money and other resources, are uncertain, these variables are sources of risk. The STEERISK spreadsheet gives producers a tool to estimate the chances of different levels of forage production, test different management and marketing strategies, and estimate returns from them. Examples of STEERISK applications include selecting the most profitable stocking rate and evaluating the profitability of weed and insect control.
    • Long-term tebuthiuron content of grasses and shrubs on semiarid rangelands

      Johnsen, T. N.; Morton, H. L. (Society for Range Management, 1991-05-01)
      Perennial plants collected from 5 north-central Arizona semiarid locations were assayed for tebuthiuron [N-5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl-N,N'-dimethylurea] and its metabolites using gas chromatography with flame photometric detection. Tebuthiuron was applied at rates ranging from 0.9 to 6.7 kg active ingredient (a.i.)/ha in 1975 through 1979. Plants were harvested in 1980 through 1986, 2 to 11 years after applications. Tebuthiuron was detected in sideoats [Bouteloua curtipendula (Michx.) Torr.] and blue grama [B. gracilis (H.B.K.) Lag. ex Griffiths] 10 years after application of 6.7 kg/ha. Metabolites of tebuthiuron were detected in blue grama 11 years after applications of 2.2, 4.5, and 6.7 kg/ha. The ratios of tebuthiuron to metabolites varied widely. The highest concentrations of tebuthiuron plus metabolites were 25 microgram/g in blue grama 10 years after application of 4.5 kg/ha, and 21 and 23 microgram/g in sideoats grama 9 and 10 years, respectively, after application of 6.7 kg/ha. Only these 3 samples of 120 samples assayed exceeded the legal limit of 20 microgram/g of tebuthiuron plus metabolites in forage plants. No samples from plots treated with 4.0 or less kg/ha exceeded 10 microgram/g of tebuthiuron plus metabolites, and only 10% of them exceeded 5 microgram/g.
    • Long-term effects of rangeland disking on white-tailed deer browse in south Texas

      Montemayor, E.; Fulbright, T. E.; Brothers, L. W.; Schat, B. J.; Cassels, D. (Society for Range Management, 1991-05-01)
      Brush is an important component of white-tailed deer (Odocoileus virginianus Raf.) habitat. We determined the long-term effects of offset disking on canopy cover, density, and diversity of brush species browsed by white-tailed deer. In 1989, we sampled vegetation in untreated strips and strips disked in 1973 in Jim Hogg County, Texas. Strips disked in 1974-1975 were sampled in Duval County, Texas, in 1985. Brush density was used to calculate species richness, evenness, and Shannon's index. In Jim Hogg County, Texas pricklypear (Opuntia lindheimeri Engelm.) density and canopy cover was greater in disked than in untreated strips. Density of other brush species was similar in disked and untreated strips. In Duval County, agarito (Berberis trifoliata Moric.) was the only brush species with lower density on disked (56 plants/ha) than on untreated (222 plants/ha) strips. Brush species richness and diversity were similar in the untreated and disked strips in both study areas. Landowners should consider disking for managing brush if they want to maintain brush diversity and browse for white-tailed deer.
    • Influence of seedbed microsite characteristics on grass seedling emergence

      Winkel, V. K.; Roundy, B. A.; Cox, J. R. (Society for Range Management, 1991-05-01)
      Successful germination and establishment of grass seedlings from surface-sown seeds requires a microsite which provides adequate soil water and temperature conditions, among other species-specific requirements. The microsite where these requirements are met has been termed a "safesite". Safesites may occur naturally as cracks and depressions in the soil surface, gravel, and plant litter, or be prepared by seedbed equipment and livestock trampling. A greenhouse study was conducted to determine the influence of seedbed microsite characteristics and soil water treatments on seedling emergence of 'Vaughn' sideoats grama (Bouteloua curtipendula (Michx.) Torr.), 'A-130' blue panic (Panicum antidotale Retz.), and 'Cochise' Atherstone lovegrass (Eragrostis lehmanniana Nees X E. tricophera Coss and Dur.). Although there were several interactions, in general, emergence of all 3 species was highest from gravel, followed by litter, cracks, and finally the bare soil surface. Bare surface sites decreased in water content more quickly than the other sites. Cochise lovegrass had high emergence in gravel under all water treatments. Small-seeded species such as Cochise lovegrass broadcast on coarse-textured surface soils may establish with minimal seedbed preparation, provided summer precipitation is adequate.
    • Grazing systems, stocking rates, and cattle behavior in southeastern Wyoming

      Hepworth, K. W.; Test, P. S.; Hart, R. H.; Waggoner, J. W.; Smith, M. A. (Society for Range Management, 1991-05-01)
      Grazing systems and stocking rates are used to influence livestock grazing behavior with the intent of improving livestock and vegetation performance. In 1982, a study was initiated to determine effects of continuous, rotationally deferred, and short-duration rotation grazing and moderate and heavy stocking rates on steer gains, range vegetation, and distance traveled by and activity patterns of steers. Steers were observed from dawn to dark on 12 dates during 1983, 1984, and 1985, and activity recorded every 15 minutes. Eight steers per treatment (system X stocking rate combination) per date were observed in 1983 and 1984, and 10 per treatment in 1985. In 1984 and 1985, map locations of all steers were recorded at the same times as activity, and distance traveled summed from distances between successive map locations. In 1984, activity of 3 steers per treatment was electronically monitored during darkness. Steers grazed approximately 8.6 hr per day during daylight and 1.6 hr during darkness. Steers grazed an average of 8.9 hr/day during daylight under moderate vs 8.1 hr under heavy stocking, but stocking rate interacted with date in 1984 and grazing system in 1985. Steers traveled farther under continuous than under short-duration rotation grazing at both stocking rates in 1984, but only at the high stocking rate in 1985. Steers had to travel farther to water in the continuous pastures, and may have had to cover a greater area in an effort to select a more desirable diet, particularly under heavy stocking. These differences were not reflected in differences in gain among stocking rates or grazing systems.
    • Grazing behavior and forage preference of sheep with chronic locoweed toxicosis suggest no addiction

      Ralphs, M. H.; Panter, K. E.; James, L. F. (Society for Range Management, 1991-05-01)
      Addiction is commonly cited as a clinical sign of locoweed (Astragalus spp. and Oxytropis spp.) poisoning. In a previous study, ewes progressively poisoned on locoweed ("locoed") in cafeteria trials did not become addicted to locoweed. Following a year of recovery, these ewes were allowed to graze locoweed-infested rangeland to determine if there was any residual preference for, or addiction to, locoweed. Neither the locoed nor control ewes consumed appreciable amounts of locoweed on rangeland where associated forage was succulent and actively growing, and where grazing pressure was sufficiently low to allow selective grazing. There was no residual preference for locoweed in previously locoed ewes. However, locoed ewes often exhibited sudden involuntary seizures when attempting to take a bite of forage. The head would tremble and tuck up under the brisket in a bobbing motion, and eye lids fluttered for a few seconds before the animal was able to proceed in feeding. Biting rate of locoed ewes was about a third less than that of the control ewes (P<.05) , and locoed ewes took fewer bites of grass than the control ewes (P<.01). Physical inhibitiion of feeding caused by the sudden seizures and reduced consumption of coarse forage, which may be more difficult to prehend, may contribute to the persistent emaciated condition and reduced productivity of some locoed animals.
    • Germination of mechanically scarified neoteric switchgrass seed

      Jensen, N. K.; Boe, A. (Society for Range Management, 1991-05-01)
      Stand establishment from neoteric switchgrass (Panicum virgatum L.) seed can be hindered due to dormancy. The objective of this study was to evaluate the effect of mechanical scarification on germination and seedling emergence of neoteric (1- to 19-month-old) switchgrass seed. Scarification for 15 or 30 seconds in a Forsberg cylinder scarifier significantly increased 14-day germination percentage for 1- to 5-month-old seed of 5 cultivars. The magnitude of increase in seedling emergence due to scarification varied across cultivars. Four-month- and 18-month-old seed lots of 'Sunburst' and a North Dakota ecotype (NDE) exhibited significant increases in germination and seedling emergence after scarification. Scarification increased overall mean germination percentage for 3 lots of Sunburst and 2 lots of NDE by 73%. Field studies are needed to determine the usefulness of mechanical scarification as a preplant treatment for neoteric seed.
    • Factors affecting weeping lovegrass seedling vigor on shinnery oak range

      Matizha, W.; Dahl, B. E. (Society for Range Management, 1991-05-01)
      Low vigor of seedlings and stand failures plague many revegetation efforts in semiarid and arid rangelands. Phototoxicity, sandbur (Cenchrus incertus M.A. Curtis) competition, seedbed preparation (plowing vs. disking), and nitrogen (N) fertilization were studied as reasons for low vigor of Ermelo weeping lovegrass [Eragrostis curvula Schrad.) Nees] seedlings on sand shinnery oak (Quercus havardii Rydb.) range in west Texas. Oak leaf residue and sandbur-dominated grass residue extracts did not affect seed germination and initial shoot growth of lovegrass seedlings. However, these residue extracts reduced root length 92% and 21%, respectively. Survival of weeping lovegrass seedlings was not affected by even 65 sandbur plants/m2. But, herbage yield was reduced 65, 72, and 79% with 30, 45, and 65 sandbur plants/m2. Early in the growing season, unfertilized plowed (P) plots had 5.6 ppm N in the 10-20 cm soil layer compared to a maximum of 3.9 ppm on other seedbed treatments. In the surface 10 cm, the P plots had less N than the disked plots. Surface-applied N fertilizer accumulated in the upper 10 cm of soil and promoted weed growth without improving weeping lovegrass stands or seedling vigor. Weeping lovegrass seedling vigor was greatest on P and least on disked plots. Thus, plowing buried weed seeds better, put resident N more deeply into the soil for better root uptake, removed allelopathic residues from seedling contact better, and provided for much higher seedling vigor than the disked seedbeds.
    • Estimation of fecal output with an intra-ruminal continuous release marker device

      Adams, D. C.; Short, R. E.; Borman, M. M.; MacNeil, M. D. (Society for Range Management, 1991-05-01)
      Efficacy of a continuous release marker device (CRD) containing chromium oxide to estimate fecal output was evaluated in two 12-day grazing trials with beef steers (n = 10, trial 1; n = 7, trial 2). Trial 1 was conducted on mature green irrigated tall wheatgrass (Elytrigia pontica [Podp.] Holub) pasture during September. Trial 2 was conducted on dormant native range during December. Fecal output was determined by total fecal collection (TFC) and the CRD for each steer. Fecal output estimates from the CRD were based on a chromium release rate (980 mg/day) provided by the manufacturer. Estimates of daily fecal dry matter output (kg) in trial 1 were 2.70 and 2.69, and in trial 2 were 3.19 and 2.89 from the TFC and CRD, respectively. Differences between TFC and CRD were not significant in trial 1 (P = 0.59) but were significant in trial 2 (P < 0.01). When averaged over days and animals, estimates of daily fecal dry matter from CRD were within 1% of TFC in trial 1 and 10% of TFC in trial 2. Estimates of daily fecal dry matter from CRD were influenced by sampling day and steer (P < 0.01); however, there was no consistent pattern to day or animal variation. Multiple days and animals are required for both TFC and CRD. We conclude that CRD provides an acceptable estimate of daily fecal output. However, to improve accuracy, TFC can be used on a subsample of animals as a double sampling technique to adjust estimates derived from CRD.
    • Effects of tree canopies on soil characteristics of annual rangeland

      Frost, W. E.; Edinger, S. B. (Society for Range Management, 1991-05-01)
      In the central California region of annual rangeland, herbage production beneath blue oak (Quercus douglasii Hook & Arn.) canopies is greater and production beneath the canopies of interior live oak (Quercus wislizenii DC) and digger pine (Pinus sabiniana Dougl.) is less than that in adjacent open grassland. The objective of this investigation was to assess the impact of these major overstory species on soil-associated characteristics in an effort to explain this tree-herbage production relationship. Greater amounts of organic carbon (OC), greater cation exchange capacity (CEC), lower bulk density, and greater concentrations of some nutrients were found beneath blue oak canopies than in open grassland. This explains, at least in part, the increased herbage production beneath blue oak canopy.
    • Effects of revegetation on surficial soil salinity in panspot soils

      Hopkins, D. G.; Sweeney, M. D.; Kirby, D. R.; Richardson, J. L. (Society for Range Management, 1991-05-01)
      Panspots and transition zone panspots (slickspots) from a Leptic/Typic Natriboroll soil complex in western North Dakota were compared to determine the effects of secondary plant succession upon soil properties. Herbage and rooting characteristics were evaluated among panspot, transition zone, and adjacent well-vegetated Belfield soils using point frame data and a modified dry ashing technique. The effects of vegetation upon soil electrical conductivity (EC) were tested using gradient transects aligned perpendicular to boundaries between panspots and transition zones. Transition zones had 40% more total forage and twice the litter found in panspot areas. Thirteen of 17 gradient transects showed an inverse relationship between soil EC and distance into transition zones at the 0 to 5 cm depth. Significantly higher root-mass was obtained in the 0 to 5 cm depth in transition zones compared to panspots. A conceptual model based on subsurface water flow is presented to explain the polygonal cracking that was observed only in transition zone surfaces initiating a series of interactions resulting in natural reclamation of the transition zone soil.
    • Economics of broom snakeweed control on the Southern Plains

      Carpenter, B. D.; Ethridge, D. E.; Sosebee, R. E. (Society for Range Management, 1991-05-01)
      Revenues associated with controlling broom snakeweed (Xanthocephalum sarothrae) on 6 soils with heavy, moderate, and light infestations of snakeweed were estimated. The analysis considered economic returns associated with grass yield response and those from livestock efficiency gains. Results indicate that control of moderate and heavy infestations is generally economically feasible, but treatment of light infestations does not pay. The economic benefits from livestock efficiency gains are generally greater than the value of increased grass production.