• The Use of a Portable Computer for Real-Time Recording of Observations of Grazing Behavior in the Field

      Demment, M. W.; Greenwood, G. B. (Society for Range Management, 1987-05-01)
      A real-time system for recording grazing behavior in the field is described. A NEC 8201a portable computer was programmed to allow the incidence, duration, and sequence of behaviors to be recorded. This system was used in the field to record bites, chews, steps, and swallows of grazing cattle. Data files were analyzed to determine biting, stepping, and swallowing rates as well as bites per feeding station. Durations of all activities can be summarized. This system permits the observer to record accurately feeding behavior and reduce significantly the time and cost of processing data.
    • The Influence of Grazing Pressure on Rooting Dynamics of Caucasian Bluestem

      Svejcar, T.; Christiansen, S. (Society for Range Management, 1987-05-01)
      Caucasian bluestem (Bothriochloa caucasica (Trin.) C.E. Hubb.) is a warm-season grass introduced from Eurasia that is currently used for reseeding farmland and depleted range in the Southern Great Plains. Although this species is thought to be grazing tolerant, little specific information is available concerning its response to grazing. Variable (put-and-take) stocking was used to maintain heavy (3 to 8 steers/ha) and light (2.5 to 4.5 steers/ha) grazing treatments during mid May to late September from 1983 to 1985. Seasonal changes in root mass and root length to a depth of 60 cm were measured the first 2 years, and end-of-season root length was measured the third year. Leaf area index (LAI) was measured during the first 2 years. Peak root mass was 27 and 46% less in heavily relative to lightly grazed swards in 1983 and 1984, respectively. Total root length for heavily grazed swards was 33 and 45% less than lengths of lightly grazed swards in 1983 and 1984, respectively. Heavy grazing resulted in a relatively larger reduction in LAI than in either root mass or length, and thus the ratio of absorbing root surface to transpiring leaf surface was greater for heavily grazed than lightly grazed plants. This increased ratio may explain our previous observation that heavy grazing resulted in an improved water status of leaf tissue. End-of-season total root length over the 3-year period (15 to 18 and 24 to 28 km/m2 for heavily and lightly grazed swards, respectively) was remarkably consistent given the variable climatic conditions over the study period.
    • Relationships Between Va Mycorrhizal Fungi and Plant Cover Following Surface Mining in Wyoming

      Waaland, M. E.; Allen, E. B. (Society for Range Management, 1987-05-01)
      Spoil spore counts of vesicular arbuscular mycorrhizal (VAM) fungi, VAM root infection, and percent cover of plants were assessed on reclaimed soil and spoil (1-6 years old), orphan spoil (10-31 years old), and undisturbed native sites. There was no relationship of site age with spore densities. Topsoiled sites almost always had significantly higher spore counts than spoil sites (reclaimed or orphan), indicating the importance of substrate on spore colonization and reproduction. Percent root infection of Agropyron smithii and A. dasystachyum showed no increasing trends with time in the mined sites (1-31 years), but the plants in the undisturbed site had greater infection than in any of the mined sites. There was also no correlation between percent cover of Agropyron and root infection or spore counts. These results suggest that time since disturbance is not an adequate explanation for the development of VAM infection and spore counts during the first 31 years, but that other factors such as the kind of substrate may be more important considerations.
    • Populations of Rhizobium Meliloti in Areas with Rangeland Alfalfa

      Lowther, W. L.; Rumbaugh, M. D.; Johnson, D. A. (Society for Range Management, 1987-05-01)
      The perpetuation of legumes in rangeland pasture plantings is dependent upon natural seeding and nodulation of the seedlings by naturalized soil rhizobia. This study determined the distribution and effectiveness of Rhizobium meliloti Dang. isolates in mature stands of rangeland alfalfa (Medicago sativa L.). Five sites in northern Utah and southern Idaho were studied. At each site, soil samples were taken from beneath the crown area of 10 plants and also at 50 and 100-cm intervals downslope and at right angles to the slope. Populations of R. meliloti ranged from 1.7 X 10^2 to more than 1.7× 105 per g of soil in all soil samples taken from within the crown area of established plants. The distribution of R. meliloti in soil adjacent to established plants differed with site and sampling position. R. meliloti were present in all the interplant spaces sampled on 1 site while the percentage of interplant samples with R. meliloti varied from 20% to almost 100% on the other 4 sites. Movement of R. meliloti downslope was detected only on 1 site. It was concluded that failure of R. meliloti to spread into the interplant spaces in rangeland alfalfa stands may limit natural reseeding.
    • Plot Numbers Required to Determine Infiltration Rates and Sediment Production on Rangelands in South Central New Mexico

      Wood, M. K. (Society for Range Management, 1987-05-01)
      Many studies have been made, and continue to be conducted, to determine infiltration rates and sediment production on rangelands. Most of these studies use small sample plots (<2 m2). This study determined the number of sample plots required to achieve confidence intervals of +/- 10, +/- 20 and +/- 30% of the sample mean at 80, 90, and 95% probability levels. For 80 and 90% probability levels, 20% of the mean could be achieved with 1 to 5 plots for infiltration rates, and as low as 1 or as many as 263 plots for sediment production. For dry soil moisture conditions, infiltration rates could be estimated with 4 or 5 plots, with 10 to 12 plots needed for field capacity conditions to achieve 10% of the mean with 95% confidence. Achieving 10% of the mean with 95% confidence was not considered practical for sediment production.
    • Persistence of a Lolium Perenne-Trifolium Subterraneum Pasture Under Differing Defoliation Treatments

      Motazedian, I.; Sharrow, S. H. (Society for Range Management, 1987-05-01)
      Effects of defoliation frequency and intensity on persistence of a perennial ryegrass (Lolium perenne)-subclover (Trifolium subterraneum) pasture were studied near Corvallis, Ore., during 1980 to 1983. While canopy cover of individual plant species did not differ between defoliation frequency or intensity treatments (P6.05) within years, all defoliated plots differed from the undefoliated control plots. Canopy cover of perennial ryegrass declined from its initial value of 43% in 1980 to an average of 30% and 1% in defoliated and undefoliated plots in 1983, respectively. Perennial ryegrass in defoliated plots was apparently replaced by subclover, whose canopy cover increased by 33% during the 3-year period. On undefoliated plots, however, both perennial ryegrass and subclover were replaced by annual grasses, whose canopy increased from approximately 2% in 1980 to 48% in 1983. Density of perennial ryegrass plants at the end of the trial in 1983 was highest when plots were defoliated once every 21 or 35 days compared to those defoliated every 7 days, 49 days, or the undefoliated control plots. Root biomass per plant, however, increased linearly as defoliation interval increased from 7 to 49 days between defoliation events. Viewed together, these data suggest that underutilization of grass-clover pastures may be potentially as damaging to pasture persistance as overutilization.
    • Nutrient Composition of Spotted Knapweed (Centaurea Maculosa)

      Kelsey, R. G.; Mihalovich, R. D. (Society for Range Management, 1987-05-01)
      Spotted knapweed (Centaurea maculosa Lam.) is a noxious plant that has invaded many native ranges and open woodlands of western Montana. Knapweed is generally considered to have a low palatability to domestic livestock and wildlife, but local ranchers have observed sheep, goats, and some cattle ingesting large quantities of fresh knapweed during the spring and knapweed silage and hay during the winter. Nutrient analysis of plants collected prior to flowering showed neutral detergent fiber at 24.2 to 53.0% (dry wt.), ether extract 3.1 to 9.0%, crude protein 6.2 to 18.2%, total nonstructural carbohydrates 11.0 to 27.5%, ash 4.9 to 9.3%, in vitro dry matter digestibility 53.2 to 61.8%, and gross energy 4,088 to 4,539 cal/g. Crude protein and nonstructural carbohydrates were most concentrated during the spring growth period when stems were developing. As the stems matured during summer they became more fibrous resulting in lower protein and carbohydrate levels. Just prior to flowering, tall plants with stems approaching 1 m had significantly higher fiber, but lower ether extract, carbohydrates, and in vitro dry matter digestibility than plants with stems less than 0.5 m. Crude protein, ash, and gross energy were the same for both groups. It was concluded that spotted knapweed does have some nutritional value as a livestock forage. Spring grazing of knapweed or harvesting for a winter forage may be useful in the control of this noxious plant.
    • Nondestructive Estimation of Shortgrass Aerial Biomass

      Williamson, S. C.; Detling, J. K.; Dodd, J. L.; Dyer, M. I. (Society for Range Management, 1987-05-01)
      A nondestructive technique for estimation of aboveground biomass of blue grama [Bouteloua gracilis (H.B.K) Griffiths] was designed for use on small sampling units (<1 m2). The technique combines measures of percent basal cover and mean total blade length per tiller and is recommended for experiments, such as small plot manipulations, that require an accurate and precise sampling method.
    • Leafy Spurge Control and Herbicide Residue from Annual Picloram and 2,4-D Application

      Lym, R. G.; Messersmith, C. G. (Society for Range Management, 1987-05-01)
      Annual application of picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid) and picloram plus 2,4-D [(2,4-dichlorophenoxy)acetic acid] and biannual application of 2,4-D for 5 consecutive years was evaluated for leafy spurge (Euphorbia esula L.) control. The picloram treatments were evaluated for soil residue. The experiment was located at 2 sites in eastern North Dakota and 1 site in western North Dakota on various soil types. Picloram at 0.28, 0.42, and 0.56 kg/ha provided 48, 75, and 90% leafy spurge control after 4 annual treatments, respectively. Control increased to 85 and 91% when 2,4-D at 1.1 kg/ha was added to the annual treatment of picloram at 0.28 and 0.42 kg/ha, respectively. However, 2,4-D with picloram at 0.56 kg/ha did not increase leafy spurge control compared to picloram alone. Picloram did not accumulate in the upper 15 cm of the soil profile and generally was not detected above the 2 ppbw level 12 months following each annual application. Greater picloram residue was found deeper in sandy than clay soil and in soil with high compared to low organic matter. Picloram at 500 and 250 ppbw was required to reduce leafy spurge seedling emergence and subsequent survival by 50%, respectively. However, picloram at 125 ppbw reduced leafy spurge regrowth from root segments of 4 lengths to near zero. Picloram at 8 to 32 ppbw stimulated leafy spurge seedling emergence compared to the control. Annual application of picloram at low rates gradually controlled leafy spurge, but picloram soil residues were not high enough to control subsequent seed germination and shoot regrowth from roots.
    • Leaf Water Potential Trends in Three Grasses Native to Semiarid Argentina

      Distel, R. A.; Fernández, O. A. (Society for Range Management, 1987-05-01)
      The natural grazing land of the semiarid region of central Argentina is subject to long and intense periods of drought during the hot season. The aim of the present study was to analyze the pattern of leaf water status for the cool-season grasses Piptochaetium napostaense and Stipa tenuis and the warm-season grass Pappophorum subbulbosum, which are important forage species in this grazing area. Leaf water potential, soil water potential, and relative humidity were measured during 1983 and 1984. At soil water potentials above -0.5 MPa, the leaf water potential of the 3 species showed high values at 0800, after nocturnal rehydratation, and minimum values at 1400, coincident with maximum atmospheric water demand. P. subbulbosum showed a greater capacity to withstand the drop in water potential at 1400 than did the cool-season species. During periods of low soil water potential the range of daily variation in leaf water potential was reduced in the 3 species because of marked decreases in the maximum and minimum values. Leaf water potential in the cool-season species correlated better with the deficit of atmospheric vapor pressure than with soil water potential. Leaf water potential of P. subbulbosum on the other hand showed a higher correlation with soil water potential than with atmospheric vapor pressure deficit.
    • Integration of Cattle Production and Marketing Strategies with Improved Pastures and Native Range

      Ethridge, D. E.; Nance, J. D.; Dahl, B. E. (Society for Range Management, 1987-05-01)
      Forty-eight stocker cattle enterprises on tobosagrass, bluestem, and lovegrass pastures being bought and sold at different points in the seasonal cattle price cycle were evaluated to determine the set of enterprises which maximize ranch profits. All optimal plans for the 397-ha (980 ac) ranch included enterprises which showed ranch profit gains from forfeiture of some physical weight gains for the price advantages of off-season buying/selling.
    • Infiltration Rates and Sediment Production as Influenced by Grazing Systems in the Texas Rolling Plains

      Pluhar, J. J.; Knight, R. W.; Heitschmidt, R. K. (Society for Range Management, 1987-05-01)
      Research was initiated in August 1982 at the Texas Experimental Ranch to evaluate effect of selected grazing treatments on watershed condition. Two production scale grazing treatments were sampled on 4 dates over a period of 15 months. Treatments were yearlong continuous grazing stocked at a moderate rate (MC) and a 16-paddock rotational grazing treatment stocked at a heavy rate (RG). In addition, hydrologic conditions in an ungrazed exclosure (EX) and a moderately stocked 4-pasture, 3-herd deferred rotation treatment (DR) were examined during the summer of 1982. Regression analyses indicated infiltration rates increased and sediment production declined as vegetation standing crop and cover increased, soil bulk density decreased, and soil organic matter and aggregate stability increased. Averaged across the 4 sample dates, sediment production was least (33 kg/ha) and infiltration rate greatest (89 mm/hr) in the MC treatment as compared to the RG treatment (63 kg/ha and 82 mm/hr). Infiltration rates and sediment production in the RG and DR treatments before grazing were not significantly different from those in the MC treatment; however, grazing caused a significant decline in infiltration rates and a significant increase in sediment production in both treatments. Sediment production was least in the exclosure (23 kg/ha) while infiltration rates were generally greater and sediment production less in the midgrass communities as compared to the shortgrass communities. All effects were closely related to the effect of the various treatments on vegetation standing crop and cover.
    • Herbage Standing Crop Around Eastern Redcedar Trees

      Engle, D. M.; Stritzke, J. F.; Claypool, P. L. (Society for Range Management, 1987-05-01)
      The effect of eastern redcedar (Juniperus virginiana) on understory herbage standing crop was investigated in northcentral Oklahoma tallgrass prairies. Herbage standing crop was measured under and at distances radiating away from individual trees of 2 height classes (2 m and 6 m) in 1984 and 1985. Soil water content at 2 distances from eastern redcedar trees and tree leaf water content were examined from 1982 to 1984. There was marked reduction in herbage production beneath the tree canopy, only slight reduction at the dripline, and little herbage reduction beyond the dripline. Tree height did not significantly influence herbage standing crop. Thus, herbage reduction is directly related to tree canopy area. Therefore, herbage reduction would be minimal in the early stages of tree encroachment when canopy is small. Soil water content at the tree dripline was sometimes lower than that 3 m outside the dripline, but the differences were small. Leaf water content generally followed the seasonal trend of soil water content. Burning in late spring is an appropriate prescription for eastern redcedar control since leaf water content is relatively low in late spring.
    • Effect of Hydroelutriation on Nonstructural Carbohydrates in Fibrous Roots

      Svejcar, T.; Christiansen, S. (Society for Range Management, 1987-05-01)
      Hydroelutriation can reduce the time required to remove roots from soil cores relative to conventional washing methods. However, method of washing may affect subsequent chemical analysis. We compared a hydroelutriation method to dry, hand cleaning of roots for subsequent carbohydrate content of root tissue. Fibrous roots of winter wheat (Triticum aestivum L.), johnsongrass (Sorghum halepense (L.) Pers.), Caucasian bluestem (Bothriochloa caucasica (Trin.) C.E. Hubb.), and little bluestem (Schizachyrium scoparium (Michx.) Nash) were collected on 8 March and 25 May 1985. Roots were analyzed for both soluble carbohydrates and total nonstructural carbohydrates (TNC). Soluble carbohydrates were extracted using 2.5 mM H2 SO4; the TNC extraction included a 24-h incubation with amyloglucosidase at 50 degrees C in addition to weak acid hydrolysis. There were no significant differences (P>.05) between cleaning procedures for any of the species on the first sampling date, and only Caucasian bluestem roots were significantly affected (P<.05) by cleaning procedure the second date. Hydroelutriation washing resulted in a 15% reduction in both soluble carbohydrates and TNC in Caucasian bluestem roots relative to dry, hand cleaning. In general, loss of nonstructural carbohydrates from washed fibrous roots was not a major concern in the 4 species we tested. However, in specific instances it may be necessary to use a correction factor to account for loss of chemical constituents when using hydroelutriation methods.
    • Distribution and Symbiotic Effectiveness of Rhizobium Meliloti in Rangeland Soils of the Intermountain West

      Lowther, W. L.; Johnson, D. A.; Rumbaugh, M. D. (Society for Range Management, 1987-05-01)
      Although the interaction between the host plant and its associated Rhizobium is a major factor in determining biological nitrogen fixation, competitive interactions among naturally occurring rhizobial populations can also greatly influence the success of nodulation and subsequent nitrogen fixation. To determine the influence of naturally occurring rhizobial populations on the symbiotic relationship between alfalfa (Medicago sativa L.) and Rhizobium meliloti, the distribution of naturalized populations of R. meliloti forming effective nodules on alfalfa was determined in representative rangeland soils of the Intermountain West of the United States. A total of 256 sites were sampled within 10 vegetation types where alfalfa is a potential legume for farming, wildlife, or revegetation use. R. meliloti capable of forming effective nodules on alfalfa were detected in 4 of the vegetation types (juniper-pinyon woodland, mountain mahogany-oak scrub, sagebrush steppe, and wheatgrass-needlegrass shrubsteppe). However, these rhizobia were detected in only 30% or less of those sites having a natural vegetative cover. Only where the sagebrush steppe vegetation type had been converted to wheat or alfalfa-grass mixtures were rhizobia detected in the majority of sites (81 and 100%, respectively). Populations of R. meliloti within the individual vegetation types ranged from 6 to greater than 1.7× 105 per g of soil. Isolates of these naturally occurring R. meliloti exhibited a wide range of symbiotic N-fixation effectiveness on alfalfa (cv Spredor 2) with the mean value for the 360 isolates tested being 69% of the check inoculant strains. Of the isolates tested, 48% were classified as inferior N-fixers with significantly lower plant yields than control plants inoculated with check rhizobia strains. The relatively limited distribution of detectable populations of R. meliloti in the majority of Intermountain West rangeland soils and the high percentage of these that were inferior in N-fixing capability underscores the need to inoculate alfalfa with highly effective and competitive strains of R. meliloti.
    • Defoliation of Intermediate Wheatgrass Under Seasonal and Short-Duration Grazing

      Pierson, F. B.; Scarnecchia, D. L. (Society for Range Management, 1987-05-01)
      Defoliation of intermediate wheatgrass (Agropyron intermedium by cattle was examined under seasonal and short-duration grazing. Tiller height, number of green leaves per tiller, phenological status, and defoliation frequency were measured on individually marked tillers during 2 grazing seasons. Defoliations at high and low stocking densities (5.2 and 2.6 animal-units/ha) were examined during the 1983 growing season. At equal stocking rates, standing crop decreased more rapidly under low stocking density. Mean tiller height and mean number of leaves per tiller decreased linearly over time in both treatments. In 1984, 14 heifers were moved through 3 rotations of an 8 subunit short-duration grazing system in 72 days. A larger fraction of tiller height and a higher number of green leaves per tiller were defoliated during rotation one than during rotation three. Animals grazed the greatest number of tillers during rotation one. Biting rate varied logarithmically with the mean number of green leaves per tiller. Time spent grazing was significantly and inversely related to the mean number of green leaves per tiller. This result suggests that animals were selectively grazing green leaves over coarse stem, and spent more time searching for them as their numbers decreased.
    • Crude Terpenoid Influence on In Vitro Digestibility of Sagebrush

      Striby, K. D.; Wambolt, C. L.; Kelsey, R. G.; Havstad, K. M. (Society for Range Management, 1987-05-01)
      The influence of crude terpenoid content on in vitro organic matter digestibility (IVOMD) was determined for basin big sagebrush (Artemisia tridentata Nutt. ssp. tridentata), Wyoming big sagebrush (A.t. ssp. wyomingensis Beetle and Young), mountain big sagebrush (A.t. ssp. vaseyana [Rydb.] Beetle), and black sagebrush (A. nova Nels.). IVOMD was determined using mule deer (Odocoileus hemionus hemionus), sheep (Ovis ammon aries), and steer (Bos taurus) rumen inocula with current year's growth collected from the 4 taxa at a common site on 1 Jan., 15 Feb., and 1 Apr. 1981. All inocula had similar digestive efficiency. Extracting crude terpenoids from foliage increased IVOMD by an average of 12.3% overall. Few differences in IVOMD among taxa and dates were evident in foliage after crude terpenoids had been extracted. Order of increasing digestibility among taxa without crude terpenoids extracted was black sagebrush, mountain, Wyoming, and basin big sagebrushes, respectively. IVOMD generally increased from January to April as crude terpenoids decreased. Crude terpenoid concentrations were lowest in mountain big sagebrush, intermediate in black sagebrush and Wyoming big sagebrush, and greatest in basin big sagebrush.
    • Caryopsis Weight and Planting Depth of Blue Grama. II. Emergence in Marginal Soil Moisture

      Carren, C. J.; Wilson, A. M.; Cuany, R. L. (Society for Range Management, 1987-05-01)
      Blue grama [Bouteloua gracilis (H.B.K.) Lag. ex Steud.] has not been able to establish itself, or to be successfully planted, from seed on abandoned croplands of the Central Plains. The objectives of this study were to test blue grama plant material under limited moisture and develop methods for improving emergence and establishment of blue grama seedlings. Experiments were conducted in the greenhouse and at the Central Plains Experimental Range near Nunn, Colorado, with 3 accessions. Under limited moisture conditions in the greenhouse, seedlings emerged better from planting depths of 2.0 and 2.5 cm than from depths of 0.5, 1.0 or 1.5 cm. Higher caryopsis weight was associated with a significant increase in percentage emergence at all planting depths. Accession PM-K-1483 had greatest emergence, followed by 'Hachita' and 'Lovington'. Under favorable soil moisture conditions in the field (2 cm of water applied at planting dates in June and July 1981), deep planting resulted in decreased emergence. Averaged over all planting depths, percentage emergence increased nearly 2-fold with an increase in caryopsis weight from 39 to 59 mg/100. When soil moisture conditions were marginal (only 1 cm water added), satisfactory emergence was obtained only when high-weight seeds were planted at a depth of 2 cm. Soil at a planting depth of 1 cm dried quickly and prevented emergence. Genetic improvement of caryopsis weight combined with planting at depths of about 2.0 cm should improve the emergence and establishment of blue grama seedlings.
    • Caryopsis Weight and Planting Depth of Blue Grama. I. Morphology, Emergence, and Seedling Growth

      Carren, C. J.; Wilson, A. M.; Cuany, R. L.; Thor, G. L. (Society for Range Management, 1987-05-01)
      Blue grama [Bouteloua gracilis (H.B.K.) Lag. ex Steud.] has been difficult to establish from seed on disturbed areas of the Central Plains. The objective of this study was to investigate the relationship of caryopsis weight, planting depth, and genetic variability on seedling emergence of blue grama. Two experiments were conducted in the greenhouse under favorable moisture conditions with 3 accessions and various combinations of caryopsis weight and planting depth. Measurements included rate of germination and emergence as an index, percentage emergence, shoot length, shoot weight, seminal root length, coleoptile length, subcoleoptile internode length and weight, adventitious root weight, and longest adventitious root length. The length of the subcoleoptile internode increased in response to greater planting depth but weight per unit length decreased. If this indicates a decrease in internode diameter it could decrease the rate of water transport through the internode. Deep plantings were not advantageous to emergence or seedling growth under favorable soil moisture conditions and caused a delay in emergence and decreased percentage emergence, shoot weight, and adventitious root weight. High caryopsis weight was associated with an increase in emergence, weight per unit length of the subcoleoptile internode, coleoptile length, shoot weight, and adventitious root weight. Therefore, high caryopsis weight is advantageous in the deep planting of blue grama seeds and allows seeds to be planted deeper to take advantage of moisture for germination and emergence.