• 14- Vs. 42-Paddock Rotational Grazing: Aboveground Biomass Dynamics, Forage Production, and Harvest Efficiency

      Heitschmidt, R. K.; Dowhower, S. L.; Walker, J. W. (Society for Range Management, 1987-05-01)
      Research was initiated at the Texas Experimental Ranch in 1981 to quantify the effects of 2 stocking densities, equivalent to 14- and 42-paddock rotational grazing (RG) treatments, on aboveground biomass dynamics, aboveground net primary production (ANPP), and harvest efficiency of forage. Baseline data were collected in 1981 from 3 adjacent 30-ha paddocks in a 14-paddock, cell designed RG treatment. Near the beginning of the 1982 growing season the center paddock was subdivided into three, 10-ha paddocks to establish the RG-42 treatment. Stocking densities in the 14- and 42-paddock treatments were 4.2 and 12.5 AU/ha, respectively, from March 1982 to June 1984 and 3.0 and 9.1 AU/ha from June to November 1984. During 1981, estimated ANPP in the two RG-14 paddocks averaged 4,088 kg/ha as compared to 5,762 in the single RG-42 paddock. Following subdivision, ANPP in the RG-14 paddocks averaged 2,533 kg/ha as compared to 2,670 kg/ha in the RG-42 paddocks. Although ANPP varied significantly among the 4 years of the study it was not affected by density treatment. Likewise, harvest efficiency varied among years but was unaffected by density treatment. Average harvest efficiency over the 4 years was about 42%. Aboveground biomass dynamics were also generally unaffected by density treatments.
    • 14- Vs. 42-Paddock Rotational Grazing: Forage Quality

      Heitschmidt, R. K.; Dowhower, S. L.; Walker, J. W. (Society for Range Management, 1987-07-01)
      Research was initiated at the Texas Experimental Ranch in 1981 to quantify the effects of 2 livestock densities on forage quality in a rotational grazing (RG) treatment. Livestock densities evaluated were equivalent to 14 and 42-paddock RG treatments. Baseline data were collected in 1981 from 3 adjacent 30-ha paddocks in a 465-ha, 14-paddock, cell designed RG treatment stocked at a rate of 3.6 ha/cow/year. Near the beginning of the 1982 growing season the center paddock was subdivided into three, 10-ha paddocks to establish the RG-42 treatment. Herbage standing crop was harvested before and after each grazing event during the 40-month period, separated by species or species group into live and dead tissue, and each fraction analyzed for percentage crude protein (CP) and organic matter digestibility (OMD). Livestock density had minimial effect on forage quality. Live tissue was of higher quality than senesced tissue regardless of plant species. Increases and decreases in overall quality during grazing periods were positively associated with rates of plant growth. Number of periods when forage quality increased or decreased during grazing and magnitude of change were unaffected by treatment. Lack of significant treatment effects on forage quality is attributed to the general absence of significant treatment effects on forage production, species composition, and live/dead ratios.
    • 1990 President's Address: SRM Today and Tomorrow

      Bedell, Thomas E. (Society for Range Management, 1990-03-01)
    • A 3-Year Evaluation of Taste Aversion Coyote Control in Saskatchewan

      Gustavson, C. R.; Jowsey, J. R.; Milligan, D. N. (Society for Range Management, 1982-01-01)
      Taste aversion programs using lithium chloride (LiCl) in sheep baits and carcasses have been applied in Washington to one sheep herd for 2 years; applications have been made in California and in Saskatchewan on 46 herds over 3 years. Ten of these 46 herds were available for statistical analysis, indicating a significant reduction in the percent of sheep lost to coyotes. All applications have suggested reduced sheep losses to coyotes (Canis latrans). This method of predation control may cost less than traditional techniques, save sheep, and should allow coyotes to carry out positive functions in the ecosystem.
    • A Basis for Relative Growth Rate Differences Between Native and Invasive Forb Seedlings

      James, Jeremy J.; Drenovsky, Rebecca E. (Society for Range Management, 2007-07-01)
      The ability of invasive plants to achieve higher relative growth rates (RGR) than their native counterparts has been widely documented. However, the mechanisms allowing invasives to achieve higher RGR are poorly understood. The objective of this study was to determine the basis for RGR differences between native and invasive forbs that have widely invaded nutrient-poor soils of the Intermountain West. Six native and 6 invasive forbs were seeded in pots in a greenhouse, and 4 harvests were conducted over a 2-month period. These 4 harvests were used to calculate RGR and the components of RGR, net assimilation rate (rate of dry matter production per unit leaf area), leaf area ratio (LAR, leaf area per unit total plant mass), leaf mass ratio (the proportion of biomass allocated to leaves), and specific leaf area (SLA, leaf area per unit leaf biomass). Mean RGR of the 12 study species ranged between 0.04 and 0.15 g g-1 d-1 but was significantly higher for invasive forbs compared to native forbs (P = 0.036). The higher RGR achieved by invasive forbs was due mainly to a greater SLA and LAR. This indicates that invasive forbs achieved higher RGR than natives primarily by creating more leaf area per unit leaf mass, not by allocating more biomass to leaf tissue or by having a higher net rate of dry matter production. A high degree of variation in RGR, SLA, and LAR was observed in native forbs, suggesting that the ability to design weed-resistant plant communities may be improved by managing for specific functional traits as opposed to functional groups. 
    • A Case Study Evaluating Economic Implications of Two Grazing Strategies for Cattle Ranches in Northwest Argentina

      Quiroga, R. Emiliano; Blanco, Lisandro J.; Ferrando, Carlos A. (Society for Range Management, 2009-09-01)
      In the Argentinean Chaco Arido region, cattle production based on cow-calf operations is the principal source of agricultural income, and rangeland is the main forage source for cattle. Traditional grazing strategy (TGS, high stocking rate and continuous grazing) is considered the main cause of current rangeland degradation. Research shows that rangeland and cattle production improvements are possible when using a conservative grazing strategy (CGS, moderate stocking rate and rest rotation grazing). The aim of this research was to compare the effects of TGS and CGS applications on economic results for a cattle ranch in the region. To achieve this objective we used an approach that included estimations of forage and cattle production, and economic results. The study period was 1972/73–1983/84. Results showed that during the study period forage production and herd size were almost doubled with CGS, but maintained with TGS. The difference in net income between CGS and TGS (in Argentinean pesos, ), increased linearly from negative (–2.88 ha-1) to positive (4.48 ha-1) in the first 4 yr, and then was maintained at positive values (averaging 4.48 ha-1). Data suggest that CGS leads to higher productivity and better economic results than TGS in the medium and long terms. 
    • A Case Study for Optimal Allocation of Range Resources

      D'Aquino, S. A. (Society for Range Management, 1974-05-01)
      A linear programming model was developed to help in the management of range resource systems. This analysis simultaneously considers per acre management costs and resulting per animal gross revenues. The management plan sets out a season-by-season use of land areas and associated forage resources with the objective of maximizing net dollar returns. Procedures developed in this study may also be applied to public resource management problems.
    • A chamber design for measuring net CO2 exchange on rangeland

      Angell, R.; Svejcar, T. (Society for Range Management, 1999-01-01)
      Net carbon exchange of terrestrial ecosystems will likely change as atmospheric CO2 concentration increases. Currently, little is known of the annual dynamics or magnitude of CO2 flux on many native and agricultural ecosystems. Remoteness of many ecosystems has limited our ability to measure CO2 flux on undisturbed vegetation. Today, many plant ecologists have portable photosynthesis systems with which they make single-leaf photosynthesis measurements. Utility of this equipment is enhanced when canopy-level CO2 flux is also measured. We designed a portable 1-m3 closed chamber for use in measuring CO2 exchange in short statured vegetation with widely varied canopy structure. The design includes external ductwork equipped with doors which are used to open the chamber for ventilation with outside air between measurements. The chamber was tested on a Wyoming big sagebrush (Artemisia tridentata ssp. Wyomingensis Nutt.)/Thurber's needlegrass (Stipa thurberiana Piper) community using 10 plots equally divided between shrub and interspace. The ductwork and doors provided adequate ventilation to allow consecutive measurements of CO2 flux without removing the chamber from the plot. The chamber could differentiate CO2 flux between plots with sagebrush and those with grass only, even at relatively low fluxes. Net CO2 uptake per unit ground area was greater (P = 0.04) on sagebrush-grass plots (7.6 +/- 1.4 micromoles m-2 s-1) than on interspace plots without sagebrush (3.1 +/- 1.0 micromole m-2 s-1). Chamber and leaf temperature increased by an average of 0.5 and 1.2 degrees C, respectively, during measurements.
    • A Common-Garden Study of Resource-Island Effects on a Native and an Exotic, Annual Grass After Fire

      Hoover, Amber N.; Germino, Matthew J. (Society for Range Management, 2012-03-01)
      Plant-soil variation related to perennial-plant resource islands (coppices) interspersed with relatively bare interspaces is a major source of heterogeneity in desert rangelands. Our objective was to determine how native and exotic grasses vary on coppice mounds and interspaces (microsites) in unburned and burned sites and underlying factors that contribute to the variation in sagebrush-steppe rangelands of the Idaho National Lab, where interspaces typically have abiotic crusts.We asked how the exotic cheatgrass (Bromus tectorum L.) and native bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] A. Lo¨ ve) were distributed among the microsites and measured their abundances in three replicate wildfires and nearby unburned areas. We conducted a common-garden study in which soil cores from each burned microsite type were planted with seed of either species to determine microsite effects on establishment and growth of native and exotic grasses. We assessed soil physical properties in the common-garden study to determine the intrinsic properties of each microsite surface and the retention of microsite soil differences following transfer of soils to the garden, to plant growth, and to wetting/drying cycles. In the field study, only bluebunch wheatgrass density was greater on coppice mounds than interspaces, in both unburned and burned areas. In the common-garden experiment, there were microsite differences in soil physical properties, particularly in crust hardness and its relationship to moisture, but soil properties were unaffected by plant growth. Also in the experiment, both species had equal densities yet greater dry mass production on coppice-mound soils compared to interspace soils, suggesting microsite differences in growth but not establishment (likely related to crust weakening resulting from watering). Coppice interspace patterning and specifically native-herb recovery on coppices is likely important for postfire resistance of this rangeland to cheatgrass./La variación suelo-planta en relación con la isla de recursos de las plantas perennes y los montículos intercalados con la presencia de inter-espacios relativamente desnudos es la mayor fuente de heterogeneidad en pastizales áridos. Nuestro objetivo fue determinar cómo pastos nativos y exóticos varían con montículos y espacios intermedios (micro-sitios) en aéreas quemadas y no quemadas, y los factores principales que contribuyen a tal variación en los pastizales de Artemisia de Idaho National Lab. Donde los inter-espacios típicamente tienen capas abióticas. Nos preguntamos cómo el pasto exótico cheatgrass (Bromus tectorum L.) y el pasto nativo bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] A. Löve) se distribuyeron entre los micro-sitios, y medimos su abundancia en tres replicas de incendios forestales y áreas adyacentes no incendiadas. Se condujo un estudio común de jardín en el cual muestras de suelo de cada micro-sitio incendiado se sembró con semillas de cada especie para determinar el efecto de los micro-sitios en el establecimiento y crecimiento de los pastos nativos y exóticos. Las propiedades físicas del suelo se midieron como en un estudio típico de jardín para determinar las propiedades intrínsecas de la superficie de cada micro-sitio, y las diferencias en la retención de suelo en cada micro-sitio después de la transferencia de los suelos al jardín, para el desarrollo de las plantas, y para los ciclos de humectación/secado. En el primer estudio, sólo la densidad de bluebunch wheatgrass fue mayor en los montículos que en los inter-espacios en ambas áreas incendiadas y no incendiadas. En el experimento común de jardín, se presentaron diferencias en los micro-sitios relativos a las propiedades físicas del suelo, particularmente en la dureza de la corteza y su relación con la humedad, pero las propiedades del suelo no se afectaron por el crecimiento de las plantas. De igual manera en el experimento, ambas especies tuvieron iguales densidades pero mayor producción de materia seca en los suelos de los montículos comparado con los suelos de los inter-espacios, sugiriendo diferencias entre los micro-sitios en crecimiento pero no en establecimiento (probamente relacionado con el debilitamiento de la corteza como resultado del riego). Los patrones de los montículos e inter-espacios y específicamente la recuperación de herbáceas nativas en los montículos es probablemente importante para la resistencia de este pastizal a la invasión cheatgrass después de la presencia de incendios forestales.
    • A Comparison of Average Variable Costs of Private vs. Public Land Ranches in Southeastern Montana

      Lacey, J. R.; Workman, J. P. (Society for Range Management, 1986-07-01)
      A study was conducted in southeastern Montana to determine the effects of federal range grazing on cattle ranch average variable operating costs per animal unit. Data were obtained through personal interviews in 1980 with 68 ranches in six southeastern Montana counties. T-tests were used to determine if the average variable costs per animal unit were less on ranches that rely on federal ranges than on ranches that do not. Annual variable costs per animal unit averaged $158 and $144, respectively, for ranches obtaining 0-4% and 5-51% of total forage from federal lands. However, this difference was not statistically significant. Regression analysis did indicate that variable costs per animal unit were significantly affected by the percentage of total ranch income from crop sales.
    • A Comparison of Continuous and Rotational Grazing

      Walton, P. D.; Martinez, R.; Bailey, A. W. (Society for Range Management, 1981-01-01)
      Continuous and rotational grazing of a brome-alfalfa-creeping red fescue pasture was compared at the University of Alberta Ranch in 1975, 1976, 1977, and 1978. Productivity, in terms of animal weight gain and dry-matter consumption, was studied together with changes in the sward composition. In 1977 and 1978 the weight gains from the rotationally grazed areas were nearly double those obtained from continuous grazing (218 vs 119 kg/ha). The percentage by weight of alfalfa in the sward increased under rotational grazing from 23 to 47%. The herbage in the rotationally grazed field was more digestible and contained more calcium, magnesium, copper, and crude protein than did that in the continuously grazed area. Animals in the continuously grazed fields spent 2.4 hours longer per day grazing than did the animals which were rotationally grazed.
    • A comparison of drills for direct seeding alfalfa into established grasslands

      Waddington, J. (Society for Range Management, 1992-09-01)
      Information is presented on the suitability of various drills for direct seeding into permanent pastures and rangelands in Saskatchewan. Strips of sod 30 to 100-cm wide were killed during the growing season by glyphosate (N-[phosphonomethyl] glycine) in grazing lands at several sites in Saskatchewan. Six drills: 1 with a powered disk furrow opener, 2 with hoe openers, and 3 with rolling disk openers were used to seed measured amounts of alfalfa (Medicago sativa L.) seed in the killed strips in late fall of the same year or early the subsequent spring. Drill performance was assessed during the seeding operation, and emerged seedlings were counted early the following growing season. Seedling emergence ranged from near 0 to 48% of seed sown. Soil moisture conditions in early spring, which in turn were a function of winter precipitation, were a major limitation on seed germination. All of the furrow-opening mechanisms were capable of placing seed at a suitable depth for successful establishment in some situations. The best seedling emergence was obtained with drills having each opener suspended independently with sufficient weight to penetrate dead thatch and hard ground, and with mechanisms to control seeding depth and pack the soil around the seeds.
    • A Comparison of Esophageal Fistula and Fecal Material to Determine Steer Diets

      Vavra, M.; Rice, R. W.; Hansen, R. M. (Society for Range Management, 1978-01-01)
      Cattle diets were determined by esophageal fistula and fecal material collection procedures from yearling cattle grazing shortgrass range in northeastern Colorado. Diets were quantified by microhistological procedures from samples collected in June, July, August, and December of 1969; and June, July, and August of 1970. Total grasses occurred significantly less in esophageal samples, while total forbs were significantly lower in fecal samples. Individual grass species did not appear to follow a set pattern of variation from esophageal to fecal sampling; some were greater in fecal samples while others were greater in fistula samples. Forbs occurred at greater percentages in fistula samples, with the exception of burning bush (Kochia scoparia) in 1969. Correlation and regression analysis revealed little relationship in botanical composition determined on fecal and esophageal samples. However, an importance value ranking revealed esophageal and fecal samples were similar when individual species were ranked from the most common to the least common in the diet.
    • A Comparison of Four Distance Sampling Techniques in South Texas Live Oak Mottes

      Beasom, S. L.; Haucke, H. H. (Society for Range Management, 1975-03-01)
      Four distance sampling techniques; point-center-quarter (PCQ), random pairs (RP), nearest neighbor (NN), and closest individual (CI) were compared to total counts to determine accuracy of density and relative frequency approximations in a live oak (Quercus virginiana) motte vegetative type in South Texas. The PCQ method was the most accurate for estimating density, followed in decreasing order by RP, CI, and NN. Only the NN approximation was significantly different from the actual density. The PCQ method also provided the most accurate relative frequency approximations, followed in decreasing order by RP, NN, and CI.
    • A Comparison of Four Methods Used to Determine the Diets of Large Herbivores

      McInnis, M. L.; Vavra, M.; Krueger, W. C. (Society for Range Management, 1983-05-01)
      Esophageal fistulation, stomach content analysis, fecal analysis, and forage utilization were compared as techniques for determining food habits of large herbivores. Each technique was evaluated based upon information collected using bi-fistulated (esophageal and rumen) sheep during 2 study phases. In the first study phase, microscope slide mounts were made of plant fragments collected from the esophagus, rumen, and feces of 10 confined sheep fed a hand-composited mixture of forage. Dietary composition as determined by each technique was compared to the original feed. Stomach content analysis and fecal analysis produced dietary estimates higher in grasses and lower in forbs than the known feed values. Esophageal fistulation results were not significantly different from the known feed values. In the second study phase, esophageal, rumen, and fecal collections were gathered from 16 sheep grazing a common plant community. Ocular estimates of forage utilization were made concurrently. All data were converted to percent composition on a dry weight basis for comparisons. Significant differences in percent diet composition among techniques occurred for 18 of the 31 plant species consumed. Diets determined by stomach content analysis and fecal analysis were significantly higher in grasses and lower in forbs than those determined by esophageal fistulation and ocular estimates of utilization.
    • A comparison of frontal, continuous, and rotation grazing systems

      Volesky, J. D.; O'Farrell, F. De Achaval; Ellis, W. C.; Kothmann, M. M.; Horn, F. P.; Phillips, W. A.; Coleman, S. W. (Society for Range Management, 1994-05-01)
      Two 2-year trials were conducted to evaluate and compare frontal, continuous, and 2-paddock rotation grazing systems on 'Plains' Old World bluestem (Bothriochloa ischaemum (L.) Keng.). Frontal grazing allows livestock a continuous opportunity to graze fresh forage via a livestock-pushed, sliding fence which allocates and controls grazing within a pasture. Trial 1 treatments included frontal grazing at a very high stocking density of 13.3 head ha-1 and continuous grazing at 4 stocking densities described as low, moderate, high, and very high. The mechanical design and components of our frontal grazing system were quite adequate in terms of the system's operation and interaction with the livestock herd. Significant (P < 0.05) linear relationships were found for regressions of daily gain on stocking rate and grazing pressure index, and for gain ha-1 on stocking rate and grazing pressure index. Year effects were evident in all regressions. Trial 2 treatments included frontal, continuous, and rotation grazing systems initially stocked at 6.7 head ha-1. Mid-season reductions in stocking density were made in continuous and rotation grazing to ensure that these treatments would have adequate forage to continue until frontal grazing completed its second cycle and to achieve an end-of-season standing crop which was similar in all 3 treatments. Season-long daily gains under frontal grazing were not significantly different compared to continuous grazing (P > 0.05); however, they were less than those under rotation grazing (P < 0.05). Frontal grazing provided about 100 more steer-days per hectare of grazing than either continuous or rotation grazing. However, steer production was not significantly different among treatments and averaged 296 kg ha-1 (P > 0.05).
    • A Comparison of In Vitro and In Vivo Feed Digestibility by White-tailed Deer

      Ruggiero, L. F.; Whelan, J. B. (Society for Range Management, 1976-01-01)
      Two captive, rumen-fistulated, white-tailed deer (Odocoileus virginianus) were used to evaluate the two-stage in vitro microdigestion technique as an estimator of in vivo dry-matter digestibility. The technique provided digestibility percentages that departed only slightly from in vivo values for the artificial ration tested.
    • A comparison of methods to determine plant successional stages

      Winslow, S. R.; Sowell, B. F. (Society for Range Management, 2000-03-01)
      Twenty-six, 0.04 ha macroplots were sampled on 9 range sites in southwestern Montana to compare successional scores and condition classifications of range condition analysis and United States Forest Service (USFS) Ecodata and Ecopac (Strata) analysis methods. Range condition scores (0-100%) and range condition classes (poor, fair, good, excellent) were derived from the traditional Soil Conservation Service range condition analysis method, with the exception that only major decreaser and increaser graminoids and shrubs were individually clipped and bagged. Ecological status scores (1-100%) and ecological condition classes (low, mid, high, very high) were determined with United States Forest Service Ecodata methods. Range condition score means were greater (p < 0.02) than ecological status score means (48% vs 41%). Standing crop biomass affected differences (p < 0.001) between range condition scores and ecological status scores. Lower producing sites had greater range condition scores than ecological status scores and higher producing sites had greater ecological status scores than range condition scores. Range condition classes and ecological condition classes were not independent (p < 0.02). Differences between the 2 methods were attributable to the use of species composition by weight for the range condition analysis and the use of percent canopy cover by Ecodata methods. Rangeland managers trying to determine successional status should realize that range condition analysis and Ecodata methods produce similar condition classes but different condition scores.
    • A Comparison of Rhizobium Strains for Effective Nodulation in Kenya Clover (Trifolium semipilosum)

      Moore, Duane G.; Britten, E. J. (Society for Range Management, 1964-11-01)
    • A comparison of soil chemical characteristics in modified rangeland communities

      Dormaar, J. F.; Willms, W. D. (Society for Range Management, 2000-07-01)
      The effects of converting native prairie to simplified agronomic communities on primary production and soil quality are expected to differ over the short-term. A study was initiated at 4 locations: a Mixed Prairie with Stipa comata Trin. Rupr. dominant in the Brown Soil Zone (1994), a Mixed Prairie with S. comata and S. viridula Trin. dominant in the Dark Brown Soil Zone (1993), and 2 in the Fescue Prairie with Festuca campestris Rydb. dominant in the Black Soil Zone (1993). At each of the 4 sites, 5 treatments representing common production systems were seeded as monocultures [2 grass species, alfalfa (Medicago sativa L. 'Beaver'), and 2 spring wheat (Triticum aestivum L. 'Katepwa) seeded as either continuous or as wheat-fallow], and 1 treatment consisting of abandoned cultivation were compared with a native community in a randomized complete block design with 4 replicates. One site in the Black Soil Zone was an overgrazed prairie (2.4 animal unit month ha-1 since 1949) and a second was mostly ungrazed for the previous 50 years with occasional light fall-grazing. Soils of the modified communities were different (P < 0.05) than of the native community with respect to percent carbon and nitrogen, concentration of monosaccharides, and concentration of most phosphorus constituents. Modifying the community through cultivation and seeding usually caused a reduction in the measured variable except for NaHCO3 inorganic phosphorus that increased. Cultivation rather than the plants of the new community was believed responsible for most of the observed changes in C, N, and various P fractions and the loss of water-stable aggregates remaining on the 2.0 and 1.0 mm sieves. Although the contribution of seeded species on the chemical and physical characteristics would not have been significantly expressed in 2 to 3 years and many more years would be required to reach a steady state, monosaccharide distribution had nevertheless started to shift to one that was plant-affected.