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  Journal of Range Management, Volume 42, Number 5 (September 1989)

  Society for Range Management, 1989-09-01
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  Winter forb control for increased grass yield on sandy rangeland

  Dahl, B. E.; Mosley, J. C.; Cotter, P. F.; Dickerson, R. L. (Society for Range Management, 1989-09-01)

  Four separate studies evaluated several herbicides for reducing competition from overwintering weeds on sandy rangeland in west Texas. Air temperature was 10 degrees C with soil moisture adequate for plant growth at herbicide application (0.28 kg ae/ha) on 14 March 1985. Trichlopyr ([3,5,6-trichloro-2-pyridinyl)oxy]acetic acid); 2,4-D [(2,4-dichlorophenoxy)acetic acid]; and dicamba (3,6-dichloro-2-methoxybenzoic acid) plus 2,4-D were ineffective, while picloram 4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid); picloram plus 2,4-D; and dicamba alone adequately controlled western ragweed (Ambrosia psilostachya DC.), the major targeted weed. These treatments were repeated on 4 April 1986 when air temperature was 24 degrees C but with dry surface soils. Results were similar to those of 1985, except trichlopyr also controlled western ragweed under the warmer temperature. In another study, various rates of picloram and trichlopyr aerially applied 5 April 1986 showed that 0.07 kg ae/ha of picloram or 0.28 kg ae/ha of trichlopyr reduced (P < 0.05) western ragweed with a corresponding increase in grass production. Picloram more effectively controlled targeted forbs while trichlopyr suppressed sand shinnery oak (Quercus havardii Rydb.) more effectively. Two companion studies also evaluated picloram and picloram plus 2,4-D. In one study 0.28 kg ae/ha of picloram was applied to sand shinnery oak range on 11 March 1985. Grass yield increased from 359 kg/ha in untreated plots to 1,222 kg/ha in treated plots. Grass yield in treated areas remained greater (P < 0.05) for 3 growing seasons post-treatment. Sand shinnery oak plants at the bud burst stage were top-killed by picloram. On 14 March 1985 picloram (0.056 kg ae/ha) plus 2,4-D (0.224 kg ae/ha) was applied to sand shinnery oak rangeland. This treatment reduced forb production with a corresponding increase in grass production the year of application (P < 0.05), but effects did not persist into the second growing season. Picloram plus 2,4-D did not suppress sand shinnery oak.
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  Viewpoint: Do your digits betray you or does rounding raises your reputation?

  Wheeler, J. L.; Prasetyo, L. H.; Davies, H. I. (Society for Range Management, 1989-09-01)
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  Toxicological investigations on Toano, Wasatch, and stinking milkvetches

  Williams, M. C. (Society for Range Management, 1989-09-01)

  Toano milkvetch (Astragalus toanus Jones) synthesizes the beta-D-glucoside of 3-nitro-1-propanol (miserotoxin), a highly toxic aliphatic nitro compound, and also accumulates toxic levels of selenium. The toxicity of Toano milkvetch to 1-week-old chicks was compared with Wasatch milkvetch [Astragalus miser var. oblongifolius (Rydb.) Cronq.], which contains only miserotoxin but does not accumulate selenium; stinking milkvetch (Astragalus praelongus Sheld.), which accumulates selenium but does not contain miserotoxin; and a combination of Wasatch milkvetch and stinking milkvetch. The LD50 for chicks fed Toano milkvetch was 67.8 mg NO2/kg plus 2.7 mg Se/kg of body weight. The LD50 for Wasatch milkvetch was 105 mg NO2/kg and for stinking milkvetch 5.9 mg Se/kg. The LD50s of a combination of Wasatch milkvetch and stinking milkvetch were 66.1 mg NO2/kg and 2.7 mg Se/kg. When miserotoxin and selenium were fed together, either in Toano milkvetch or the Wasatch-stinking milkvetch combination, the LD50 for each compound was significantly lower than when they were fed separately. If seleniferous and nitro-bearing species grow sympatrically, livestock might be poisoned at lower concentrations of the individual toxic compounds if they grazed both species.
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  The effect of cattle grazing on the growth and miserotoxin content of Columbia milkvetch

  Quinton, D. A.; Majak, W.; Hall, J. W. (Society for Range Management, 1989-09-01)

  The growth and miserotoxin content of Columbia milkvetch (Astragalus miser Dougl. var. serotinus (Gray) Barneby) were examined following grazing of early growth by cows at a grassland site in southern British Columbia. Grazing behavior and forage consumption of cows were observed. Growth of Columbia milkvetch was determined by measuring the freeze-dried weight of each plant and miserotoxin levels were determined by a rapid screening method. Cows had a tendency to either avoid Columbia milkvetch or to consume it incidentally with other forage so long as there was adequate grass available. As grass became scarce the use of Columbia milkvetch increased. After being grazed, the rate of growth and the toxicity of Columbia milkvetch were substantially reduced. In comparison to ungrazed plants, the aboveground biomass of grazed plants was reduced by more than 50% and the average miserotoxin content per plant was reduced by more than 75% during a 6-week period of regrowth. While early grazing may reduce the potential hazard of Columbia milkvetch to livestock, the plant is not a preferred species and may not be consumed by cattle until other forage becomes scarce. Heavy grazing intensity may, in turn, result in low vigor of bunchgrasses and a deterioration of range condition which may result in more weeds in the plant community. Clearly these aspects of management require further study.
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  Technical Notes: A pocket computer program for collecting forage selection frequency data in the field

  Cincotta, R. P. (Society for Range Management, 1989-09-01)

  An algorithm was developed to conduct bite-count sampling employing a programmable pocket computer. The BASIC program was successfully employed to collect forage selection data on rangeland livestock at a remote field site in Tibet. The program features techniques that are applicable to developing programs for sustained frequency data collection using similar battery-powered computers. Pocket computers have been demonstrated to be powerful field tools, and their potential promise to increase as new units become available with larger memories and added features.
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  SMART: a Simple Model to Assess Range Technology

  Hart, R. H. (Society for Range Management, 1989-09-01)

  A model, more detailed than a set of stocking rate response curves but less detailed than large process models such as SPUR, was needed to evaluate the short-term effect of grazing management practices on range herbage growth and livestock production. SMART (Simple Model to Assess Range Technology) simulates the effects of stocking rate and rotation on herbage production and steer performance. Herbage growth rate is a quadratic function of herbage biomass and is adjusted for seasonal differences. Herbage intake increases with herbage biomass and digestibility and animal weight. Animal gain increases logarithmically with digestible dry matter intake and decreases with animal weight. Output of these simulations confirms that early removal of steers from pasture in autumn will increase net returns, and that short-duration rotation grazing will produce little increase in gains or returns over those achieved under season-long grazing. Development of the SMART model revealed deficiencies in our understanding of the factors controlling herbage intake.
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  Root-feeding insects of Senecio riddellii in eastern New Mexico and northwestern Texas

  Sites, R. W.; Phillips, S. A. (Society for Range Management, 1989-09-01)

  Five insect species were reared from roots of Riddle's groundsel (Senecio riddellii Torrey & Gray). Phaneta offectalis (Hulst) (Lepidoptera: Tortricidae), Cylindrocopturus armatus Champion (Coleoptera: Curculionidae), and Cochylis felix Walsingham (Lepidoptera: Cochylidae) were the most abundant, while only one individual each of the 2 other species, Smicronyx intricatus Casey (Coleoptera: Curculionidae) and an undescribed moth (Lepidoptera: Gelechiidae), was reared. A survey conducted in southeastern New Mexico and northwestern Texas indicated that infestation of Riddle's groundsel by P. offectalis is widespread. Riddle's groundsel is a new host record for these 5 insect species, and these insects are naturally occurring exploiters of this rangeland weed.
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  Observations on white-tailed deer and habitat response to livestock grazing in south Texas

  Cohen, W. E.; Drawe, D. L.; Bryant, F. C.; Bradley, L. C. (Society for Range Management, 1989-09-01)

  Since short duration grazing (SDG) was introduced to Texas, concern for white-tailed deer (Odocoileus virginianus) has magnified because they are a species of major economic importance to ranchers. The objective of this study was to observe the effects of SDG and continuous yearlong grazing (CG) on home ranges and movement indices of female deer, and on forage availability. The study was conducted on the Rob and Bessie Welder Wildlife Refuge, near Sinton, Texas. The study area included a 10-pasture SDG cell and a CG pasture, each stocked at 2.8 ha/auy. Cattle grazed each SDG paddock 2 to 8 days; paddocks were rested 32 to 47 days. A total of 3,961 radio-fixes from 11 does was collected over an 11-month study period in 1983. Monthly and annual home ranges of does were similar (P > 0.05) between SDG (207 ha) and CG (229 ha). However, white-tailed deer traveled 35% more (P < 0.05) between fixes in SDG (449 m) than in CG (332 m) from May to August, a time of greatest physiological and nutritional stress for female deer in south Texas. Also, does avoided (P < 0.05) cattle during 2 cycles of the SDG rotation. The primary trend observed was for the deer under SDG to avoid cattle concentrations by alternating between preferred habitats rather than a predictable paddock-to-paddock movement. In general, there were few differences in total grass and forb cover between SDG and CG. However, several forage species important to deer were less frequent (P < 0.05) under SDG than CG.
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  Mineral dynamics in beef cattle diets from a southern mixed-grass prairie

  Pinchak, W. E.; Greene, L. W.; Heitschmidt, R. K. (Society for Range Management, 1989-09-01)

  Acute and chronic dietary deficiencies in macro and micro minerals have significant impacts on production efficiency on rangelands throughout the world. However, limited information is available on the mineral quality of diets primarily because salivary and soil mineral contamination of esophageal extrusa precludes quantitative recovery of dietary minerals. Mineral profiles of diets can be estimated indirectly, however, if forage species composition of diets and mineral concentrations of selected forages are known. The objective of this study was to utilize this approach to estimate seasonal dynamics of phosphorus (P), calcium (Ca), potassium (K), and magnesium (Mg) in cattle diets' relative requirements. Two diet selection scenarios were developed: the first, maximum mineral intake, assumed cattle consumed only live plant tissue of a forage if it was available; the second, considered minimum mineral intake, assumed cattle consumed live and dead tissue in direct proportion to their availability. Calculated concentrations of P and Ca in diets showed P concentrations were below and Ca concentrations were above their respective requirements for spring calving cows regardless of selection scenario or season of the year. However, K and Mg concentrations varied as a function of selection scenario and season of year and ranged from adequate during periods of rapid vegetation growth to marginally inadequate during periods of water (drought) or temperature (winter) induced dormancy.
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  Matric potential of clay loam soils on arid rangelands in southern New Mexico

  Herbel, C. H.; Gibbens, R. P. (Society for Range Management, 1989-09-01)

  The matric potential of soil water is presented for 6 clay loam sites on floodplains of arid rangelands. Gypsum resistance blocks impregnated with plaster of paris were placed at 6 soil depths to 122 cm. At 4 locations, blocks were placed inside and outside a buried sheet metal cylinder so that estimates could be obtained of matric potential due to precipitation and due to precipitation plus run-in. The average annual precipitation during the approximate 20-year study period was 242 mm, slightly above the long-time average. Haplargids dominated by tobosa [Hilaria mutica (Buckl.) Benth.] had a greater probability of the matric potential greater than or equal to -1.5 MPa (wet soil) than the Calciorthids dominated by burrograss (Scleropogon brevifolius Phil.). The probability of matric potential greater than or equal to -1.5 MPa (wet soil) was as great or greater in winter as during the summer growing season. The factors affecting matric potential were amount and nature of precipitation, amount of run-in water, soil and vegetation type, position on the landscape, and microrelief.
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  Justification for grazing intensity experiments: economic analysis

  Bransby, D. I. (Society for Range Management, 1989-09-01)

  Economic arguments in favor of grazing intensity trials are provided by economic analysis of grazing intensity results from Coastal, Callie and experimental hybrid S-16 bermudagrass (Cynodon dactylon L. Pers), and by emphasizing the biological and economic differences among cultivars. Cattle buying prices of 1.20, 1.30, and 1.40/kg and price margins (selling price minus buying price) from -0.20 to 0.20 were considered on a return/ha and /animal basis, assuming land or capital to buy animals to be limiting, respectively. When price margin was -0.20, the stocking rate at which profit/ha was maximized ranged from 4.19 to 5.85 animals/ha, while profit/animal was maximized between 4.77 and 6.89 animals/ha. Corresponding ranges in average weight of herbage present/ha which maximized profit/ha and /animal were 2.83 to 3.60 Mg and 2.34 to 3.72 Mg. For a price margin of 0.20, profit/ha and /animal were maximized at stocking rates of 7.36 to 9.86 and 4.14 to 5.93 animals/ha respectively, with corresponding levels of herbage present/ha in the ranges 0.33 to 1.79 Mg and 2.73 to 4.06 Mg. Relative differences in profit/ha and /animal among cultivars did not correspond to differences in gain/ha and /animal. Economic comparison of the cultivars considered in this study would have had little relevance if only one grazing intensity had been used in the field trial. Only grazing trials with several grazing intensities per treatment can allow for the determination of economic optimum grazing intensities in respect of a wide range in economic conditions.
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  Infiltration and sediment production as affected by soil surface conditions in a shrubland of Patagonia, Argentina

  Rostagno, C. M. (Society for Range Management, 1989-09-01)

  Infiltration and sediment production of eroded and uneroded shrub interspace soils were evaluated in December 1986 in a severely grazed, arid range site in northeastern Patagonia. A rainfall simulator and small plots were used to collect the data. A desert pavement embedded in a vesicular crust characterized the surface soil of the eroded areas that occupy the lowest position in the microtopographic pattern. A granular, fine, and weak structured A horizon characterized the soil of uneroded areas. Slopes were similar for the eroded and uneroded areas. Surface soil bulk density, electrical conductivity, clay and organic matter content were significantly greater for the eroded than for the uneroded soils. Litter cover was significantly higher for the uneroded soils. Plant cover, although higher for the uneroded areas, was low (< 5%) for both eroded and uneroded areas. Mean infiltration rate at the end of 35 min, with the soil initially dry, was 0.8 and 6.1 cm/hr for the eroded and uneroded soils. respectively. For the soil initially at field capacity, infiltration decreased to 0.6 cm/hr and 4.1 cm/hr. Soil losses were higher from the eroded areas (606 kg/ha and 687 kg/ha) than for the uneroded areas (291 kg/ha and 556 kg/ha) when the soils were initially dry and at field capacity, respectively. Regression analysis indicated infiltration rate was positively related to litter cover and negatively related to gravel cover, whereas sediment production was negatively related to bulk density, plant, and gravel cover characteristics of the site.
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  Infiltration and runoff water quality response to silvicultural and grazing treatments on a longleaf pine forest

  Wood, J. C.; Blackburn, W. H.; Pearson, H. A.; Hunter, T. K. (Society for Range Management, 1989-09-01)

  The impacts of intensive vs. extensive silviculture, and moderate continuous livestock grazing vs. no livestock grazing as they relate to infiltration and runoff water quality were evaluated using rainfall simulation. Study sites were located in the Vernon District of the Kisatchie National Forest, Louisiana. Infiltration was greater, and interrill erosion, suspension-solution phase total nitrogen concentrations, and suspension-solution phase total phosphate concentrations were less from areas under extensive silviculture and no livestock grazing than from areas under intensive silviculture and livestock grazing, respectively. Intensive silviculture exposed more bare soil than extensive treatments. Litter cover and litter biomass were significantly reduced by the intensive silvicultural treatment. Livestock grazing also exposed more bare soil mainly resulting from a removal of grass cover and biomass.
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  Growth patterns of yearling steers determined from daily live weights

  Currie, P. O.; Volesky, J. D.; Adams, D. C.; Knapp, B. W. (Society for Range Management, 1989-09-01)

  Growth patterns for free-ranging yearling steers were quantified from daily live weights obtained with automatic scales which animals entered to obtain drinking water. Forty steers were monitored during each summer grazing period of 1986 and 1987. Frequency of watering and, thus, weighing on the automatic scales averaged 2.4 times/day. Significant (P < 0.01) quadratic relationships between live weight and Julian date were obtained. In 1986, predicted live weight of the steers peaked in late July to early August and then decreased through to the end of the grazing period in September. Live weight of the steers in 1987 followed a similar pattern although the late summer decrease was not as great as in 1986. When animals were periodically weighed using manual procedures, a lower rate of gain was measured in the second half than in the first half of the summer grazing period every year from 1983 through 1987. However, we were unable to specifically identify when these weight changes occurred until the automatic scales were used in 1996 and 1987. The automatic weighing equipment documented substantial within-day live weight variability among steers. This variability changed over the grazing period on a day-to-day basis. Within-day variability must be considered when establishing manual weighing schedules with conventional equipment. Live weight data in conjunction with other measurements will permit development of a more comprehensive animal-plant-climate model.
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  Effects of short-duration on winter annuals in the Texas Rolling Plains

  Weigel, J. R.; McPherson, G. R.; Britton, C. M. (Society for Range Management, 1989-09-01)

  A study was conducted in the Texas Rolling Plains to test the hypotheses that short-duration grazing increases plant density and diversity in grasslands. Densities of 9 species of winter annual forbs and 2 species of annual grass were compared in short-duration grazed and ungrazed areas for 2 years. Livestock grazing in spring and early summer affected density of 8 winter annuals the following winter. Densities of 2 grasses [little barley (Hordeum pusillum Nutt.) and six-weeks fescue (Vulpia octoflora [Walt.] Rydb.)] and 3 forbs [common broomweed (Xanthocephalum dracunculoides [DC.]), Gordon's bladderpod (Lesquerella Gordonii [Gray] Wats.), and Texas filaree (Erodium texanum Gray.)] were higher in grazed areas; 3 forbs [bitterweed (Hymenoxys odorata DC.), spurge (Euphorbia sp.), and woolly plaintain (Plantago patagonica Jacq.) were more abundant in exclosures. Richness and diversity of winter annuals generally were not affected by grazing. Increased precipitation during germination and establishment greatly increased the density of winter annuals.
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  Effects of goat browsing on gambel oak communities in northern Utah

  Riggs, R. A.; Urness, P. J. (Society for Range Management, 1989-09-01)

  Replicated populations of 5 shrub species were monitored over a 3-year period to assess community responses to intensive browsing by Spanish-type goats. Response variables included stem density, stem-size distribution skewness, stem diameter-stem production relations, and sprout abundance and weight. No species exhibited a density change. Size distribution skewness increased only in browsed oak (Quercus gambelii Nutt.) populations. Sprout weights also increased in browsed oak populations, but declined in comparably browsed serviceberry (Amelanchier alnifolia Nutt.) populations. The only other significant sprouting response was an increase in sprout numbers in browsed snowberry (Symphoricarpos oreophilus Gray) populations. Relationships between basal stem diameter and stem production of 4 species were altered by goat use. The slopes of these relations were consistently lower in browsed populations of oak and serviceberry than in adjacent control populations, indicating that browsing reduced productivity, especially of large stems. Conversely, slopes of rabbit-brush (Chrysothamnus viscidiflorus lanceolatus (Hook.) Nutt.) relations increased in goat-browsed pastures relative to those of control populations; rabbitbrush was avoided by goats. Similarly, big sagebrush (Artemisia tridentata wyomingensis Nutt.) was avoided and its stem production responded positively in communities subjected to goat browsing. Important cumulative effects of goat browsing included declines in productivity of serviceberry and oak, and an increase in that of sagebrush.
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  Effect of fertilization date and litter removal on grassland forage production

  Wikeem, B. M.; Newman, R. F.; Ryswyk, A. L. Van. (Society for Range Management, 1989-09-01)

  The effects of application dates of urea fertilizer and dormant-season removal of litter were examined on a bluebunch wheatgrass (Pseudoroegneria spicatum [Pursh] A. Love subsp. spicata)- Sandberg's bluegrass (Poa sandbergii Vasey) site in southern British Columbia. Forest grade urea, applied at 100 kg N/ha, increased the yield of both spring (53%) and summer (73%) forage compared to the unfertilized control. Spring forage production was not affected by the application date of urea. Summer forage yields, however, were 20% higher when urea was applied on snow-free (October and March) compared to snow-covered ground (November, January, and February). Dormant-season removal of litter reduced spring forage yields by different amounts (P<0.05) in 1984 (29%) and 1981 (25%). Albiet a small difference, this suggests that removal of litter may interact with annual weather conditions and confound measurements of absolute spring herbage yields in a long-term study. In contrast, dormant-season removal of litter reduced summer forage production consistently by 23% in both 1981 and 1984. This technique might therefore be used to reduce clipping time for summer plots in fertilizer trials. If absolute estimates of above ground herbage production are required, control plots should be clipped each year to account for the losses in yields induced by dormant-season removal of litter.
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  Cues cattle use to avoid stepping on crested wheatgrass tussocks

  Balph, D. F.; Balph, M. H.; Malechek, J. C. (Society for Range Management, 1989-09-01)

  This paper tests 2 hypotheses regarding the cues cattle use to avoid stepping on crested wheatgrass (Agropyron cristatum (L.) Gaertner) tussocks. The first hypothesis is that cattle are attentive to shade and avoid tussocks by stepping on light areas (soil interstices) and avoiding dark areas (tussocks). In an experiment with 90 Angus heifers placed in a short-duration grazing paddock of 8.5 ha, the animals stepped with equal relative frequency on 28 patches of bare ground, 37 disks painted the shade and color of bare ground, and 37 disks painted to match vegetation over a 24-h period. We therefore reject the shade-cue hypothesis. The second hypothesis is that cattle are attentive to the vegetation itself in their avoidance behavior, and that as they crop the vegetation the frequency of trampling increases. In experiments similar to the first, cattle stepped on 85 intact tussocks 9 times, on 85 clipped (3 to 4 cm above litter) tussocks 28 times, on 85 vegetation-free tussock mounds 107 times and on 35 patches of bare ground 130 times. These differences are statistically significant. The data are consistent with the vegetation-cue hypothesis, except that the cattle also were attentive to the elevated substrate upon which the tussock grew. We conclude that, under the test conditions, hoof action does not have an important impact on crested wheatgrass pastures used for short-duration grazing. The impact could approach importance, however, if the pasture was grazed more heavily and if the vegetation was dry and dusty.
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  Correlation of steer average daily gain with diet quality and forage phenology in an improved annual grassland

  Raguse, C. A.; Morris, J. G.; Landry, V. N. (Society for Range Management, 1989-09-01)

  Management of legume-improved annual range forage is made difficult by the rapid declines in nutritive quality and animal gains as the plants mature. An improved ability to predict occurrence of the critical spring grazing period (CSGP) when these declines begin would help in making livestock management decisions. Objectives of this study were to construct a model to describe seasonal changes in steer average daily gain (ADG); to observe changes in nitrogen concentration ([N]) and in vitro organic matter digestibility (IVOMD) related to time of season and ADG; and to relate the phenological progress of maturation of rose clover (Trifolium hirtum L.) to ADG, [N], and IVOMD. Data from 5 years of a grazing experiment were used to construct the ADG model, which consisted of 3 season-related zones which were described by a series of linear and quadratic function. Data for [N] md IVOMD from 2 spring seasons of sampling with esophageally fistulated steers, and from 1 season of hand-cut sampling of rose clover and other plant species from annual range were related to the CSGP. Nitrogen content of the forage was a more useful predictor of rapid ADG change during the CSGP than was IVOMD. The CSGP midpoint coincided with an approximately 0.5:0.5 mixture of 2 well-defined maturation stages of rose clover.

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