• Evaluating breeding seasons for cows grazing winter range and bahiagrass

      Pate, F.; Kalmbacher, R.; Martin, F. (Society for Range Management, 2000-07-01)
      Florida native range is grazed in winter and cows are moved to bahiagrass (Paspalum notatum Flugge) pasture in March for breeding and calf rearing. Winter weight loss of cows is a major problem, and one possibility to reduce it is to alter the breeding season. This 4-year study evaluated October-February range grazing with movement of cows to bahiagrass in late February for breeding and calf rearing beginning in March (spring-bred cows) vs. December-April range grazing with movement of cows to bahiagrass in May (summer-bred cows). Spring-bred cows weighed less coming off range (439 kg) than summer-bred cows (459 kg), but spring-bred cows gained more weight on bahiagrass (38 kg) by the time calves were weaned than summer-bred cows (1 kg). At weaning, there were no differences in weights of cows. Weight loss of cows on range was related to weight going onto range in the fall (r = -0.62 and -0.49 for spring- and summer-bred cows). Declining nutritive value of bahiagrass and heavy rains in the late summer and early fall appeared to lead to the inability of summer-bred cows to regain weight on bahiagrass. In 2 years, rain interfered with range burning in October which was needed to improve the palatability and nutritive value of forages for spring-bred cows, but this appeared to have no effect on cow performance. Weaning weight of calves from the spring-bred cows (205 kg) tended to be higher than that of calves from summer-bred cows (181 kg). There were no differences in pregnancy rates (74.5%). A March-May breeding season is recommended over a May-July breeding season for cows using a combination of range and bahiagrass.
    • Fire and cattle grazing on wintering sparrows in Arizona grasslands

      Gordon, C. E. (Society for Range Management, 2000-07-01)
      This paper reports on the results of a 3-year field study of the effects of spring/summer burning and cattle grazing on wintering sparrows in the grasslands of southeastern Arizona. The effects of fire were studied with 1 year of pre-burn data and 1 year of post-burn data from 1 fire, plus limited sampling from a second fire at Buenos Aires National Wildlife Refuge in Pima County, Ariz. The effects of grazing were studied by comparing study plots at a site that has not been grazed by cattle since 1968 with a nearby grazed pasture in Santa Cruz County, Ariz. Sparrow abundance was measured as the number of captures from flush-netting sessions conducted by groups of 13-30 volunteers. Vesper (Pocecetes gramineus (Gmelin)) and Savannah (Passerculus sandwichensis (Gmelin)) Sparrows responded positively to fire, while Cassin's Sparrows (Aimophila cassinhi (Woodhouse)) responded negatively. The ecologically and geographically restricted Baird's (Ammodramus bairdil (Audubon)) and Grasshopper (A. savannarum (Gmelin)) Sparrows utilized burned areas during the first post-burn winter and did not significantly respond to fire. Both Ammodramus sparrows also utilized the grazed pasture; they were more abundant there than in the ungrazed study area in 1 year. While field observations and a prior study suggest that heavy grazing can have a strong detrimental effect on Ammodramus sparrows, the results of this study suggest that moderate cattle grazing may be compatible with the conservation of these species.
    • Grass response to seasonal burns in experimental plantings

      Howe, H. F. (Society for Range Management, 2000-07-01)
      A 6-year experiment examined the effects of spring and summer fires on grasses in southern Wisconsin. Synthetic communities of C3 and C4 grasses were seeded (100 seeds m-2 species-1) in 1992 and subjected to prescribed burns in May and August of 1995 and 1997, or left unburned. By 1994 all plots were virtual monocultures of the C3 reed canary grass (Phalaris arundinacea L.). By the second post-season sample in 1998, total productivity of plots burned in May was higher (781 +/- 212 se g m-2 year-1) than those burned in August (362 +/- 28 g m-2 year-1) or left unburned (262 +/- 43 g m-2 year-1) due to the incursions of either the C4 grasses big bluestem (Andropogon gerardii Vitman), switchgrass (Panicum virgatum L), or both. These large late-season grasses are much more productive per area covered than P. arundinacea or the other two C3 grasses present, Elymus virginicus L. and Poa pratensis L. Even at this early stage of succession, C4 production in plots burned in May was 5 to 6 times that in the other 2 treatments. August burns produced a mix of C3 and C4 grasses but did not strongly favor the pre-treatment C3 dominant P. arundinacea. Unburned plots most resembled those burned in August in species composition, but differed in having 4 times the accumulated litter, perhaps foretelling divergence in C3 and C4 composition as succession proceeds.
    • Herbage volume per animal: A tool for rotational grazing management

      Duru, M.; Ducrocq, H.; Bossuet, L. (Society for Range Management, 2000-07-01)
      The objective of this study was to provide a tool for maintaining a high grazing efficiency. In a rotational grazing system, the residual sward height does not provide enough information in advance to make the recommendation. The grazing management of 4 commercial dairy farms which differed greatly in their stocking rate, was monitored over 3 spring seasons. Data were collected on the overall grazing area (sward height measurements, stocking rate, indoor feeding, nitrogen supply) and on 3 grazed fields (herbage mass, height, and nitrogen status). At the whole grazing area level, computed data were herbage volume per animal unit (HVAU). We show that the HVAU depends on the residual herbage height. Both criteria decreased when stocking rate increased. The HVAU reflects, at the whole grazing season and area levels, how the system works on grazed field over grazing cycle. The HVAU has 2 advantages: (i) It gives rough estimation of the size of the whole grazing area to achieve a high grazing efficiency; (ii) it is a means to assess a posteriori the efficiency of the grazing system regarding the consistency between stocking rate and nitrogen supply management.
    • Hydrologic responses of shortgrass prairie ecosystems

      Weltz, L.; Frasier, G.; Weltz, M. (Society for Range Management, 2000-07-01)
      Runoff hydrographs from 3 separate rainfall simulation runs at 11 different shortgrass prairie sites were evaluated to determine the hydrologic similarity within a single ecosystem at widely separated sites. There were no consistent patterns in the equilibrium runoff among sites and simulator runs. When the sites were stratified by soil type, there were differences in time-to-peak of the runoff event and the regression slope of the rising limb of the runoff ratios. Spearman's rank correlation showed no relation of the rising limb slope regression coefficient to measured vegetative characteristics across all sites. There was minimal correlation between the runoff regression coefficient and the percent cover and bare soil. Differences in the biotic components of the sites were not useful in predicting runoff characteristics. If equilibrium runoff was the measured hydrologic response, the sites were dissimilar. Using the time-to-peak and slope of the rising limb components of the runoff hydrograph, the sites were similar on the same soil type. The technique of comparing components of the runoff hydrograph, other than equilibrium runoff has promise to allow one to quickly compare responses among ecosystems to determine if they have similar hydrological functions. Our study on shortgrass prairie sites indicated that easily estimated factors such as biomass, cover and litter were not good indicators of hydrologic function. Also, it is necessary to identify which portion of the runoff event is most important in the assessment. Future hydrologic and erosion models need to develop nonlinear prediction equations to estimate infiltration rates as a function of cover, biomass, and soil properties and also to stratify soils into functional units to accurately estimate runoff rates.
    • Investigation of herbaceous species adapted to snowfence areas

      Perryman, B. L.; Laycock, W. A.; Koch, D. W. (Society for Range Management, 2000-07-01)
      Decreases in biomass and cover, as well as changes in species composition have occurred on rangelands affected by snowdrifts behind 3.8 meter tall "Wyoming" type snowfences along Interstate 80 in southeast Wyoming. Within the state of Wyoming, government agencies are responsible for the mitigation of any adverse effects associated with snowfences. These agencies need information which may aid mitigation efforts. In this study, 13 grass species and 2 tillage treatments (till and no-till) were evaluated in the field on both drift and non-drift areas, to determine the potential of each for the revegetation of snowfence sites. Evaluation was based on foliar cover at the end of the first growing season and aboveground biomass production after the second growing season. The project included plantings on 2 different soil depth sites (< 50 cm and > 50 cm) that were treated as 2 separate experiments. Results indicate that pubescent wheatgrass 'Luna' (Elytrigia intermedia [Host] Nevski), thick-spike wheatgrass 'Critana' (Elymus lanceolatus [Scribn. J.G. Smith] Gould), and 2 varieties of slender wheatgrass 'Pryor' and 'San Luis' (Elymus trachycaulus [Link] Gould ex Shinners), were superior in cover and aboveground biomass production when planted in combination with tilled plots. Tufted hairgrass (Deschampsia caespitosa [L.] Beauv.) exhibited the least potential for cover and aboveground biomass production.
    • N and P fertilization on rangeland production in Midwest Argentina

      Guevara, J. C.; Stasi, C. R.; Estevez, O. R.; Le Houérou, H. N. (Society for Range Management, 2000-07-01)
      Low soil nutrient status may be the major limiting factor to forage production in rangelands of the Mendoza plains 4 years out of 10. We studied vegetation responses to annual applications of N and P on such rangelands. Fertilizer application rates were 0 or 25 N and 0 or 11 P (kg ha-1) in a factorial arrangement. Dry matter production of grasses and palatable shrubs and crude protein (CP) content of grasses were determined annually from 1996 to 1998. Experimental plots received rains of 189, 278, and 346 mm during the 3 study years compared to mean growing season rainfall of 258 mm. Forage production was increased by N+P fertilization only in 1998 (1,390 vs 980 kg ha-1, P 0.05), producing 16.5 kg forage kg-1 N applied. Crude protein concentration was increased by N fertilization in 1997 (6.3 vs 5.3%, P < 0.05) and N+P application increased in 1998 (6.8 vs 5.7%, P < 0.05). Nitrogen and P application increased seasonal rain-use efficiency when the rainfall exceeded 300 mm. In 1998, the increase of grass production per kg N applied with and without P was 18.4 and 12.4 kg, respectively. The break-even point between rain and nutrients as the main primary production determinant on sandy soils in the central Mendoza plains is around 400 mm year-1 instead of 300 mm in other arid lands of the world. The value of meat increment derived from the N fertilization, with and without P application (US 0.07 ha-1 year-1 kg-1 N) was lower than the fertilizer cost (US 0.87 kg-1 N). A 5-fold increase in forage yields would be required to offset the cost of fertilizer. Fertilizer application did not increase forage production enough to be profitable for cattle production at present fertilizer and meat prices.
    • Perceptions and economic losses from locoweed in north-eastern New Mexico

      Torell, L. A.; Owen, L. P.; McDaniel, K. C.; Graham, D. (Society for Range Management, 2000-07-01)
      Livestock producers and others knowledgeable about the locoweed problem in northeastern New Mexico were surveyed to obtain the production information needed to estimate economic losses from locoweed (Oxytropis/Astragalus) poisoning. A partial budgeting approach was used to estimate economic losses based on animal performance differences with increasing levels of poisoning. With current production costs and 1990-96 average beef prices, annual locoweed poisoning losses were estimated to be 75 head-1 for moderately poisoned animals, and 282 head-1 for severely poisoned animals. The most common locoweed management strategy used by northeastern New Mexico ranchers was to move animals observed eating locoweed into locoweed-free areas. Rehabilitation of these animals for an extended period before sale was found to decrease economic loss relative to immediate sale. Moderately and severely poisoned animals that are rehabilitated were estimated to gain 14% and 29% less than non-intoxicated animals. Other management options including chemical locoweed control, fencing, and locoweed aversion were found to be economically justified when relatively high locoweed infestations are anticipated.
    • Plant Establishment on Angle of Repose Mine Waste Dumps

      Nowak, Robert S. (Society for Range Management, 2000-07-01)
      Angle of repose slopes associated with mine waste dumps are difficult to revegetate due to steep slope angle, poor soil properties, and potential for extensive soil erosion. We examined the extent that seed movement, seedling establishment, soil characteristics, nutrient availability, and water availability were responsible for limiting plant establishment or survival on steep (average slope ~80%), south-facing angle of repose slopes at a gold mine north of Elko, Nev. Four treatments were established: 1) unaltered mine waste soil; 2) mine waste soil with fertilizer; 3) mine waste soil draped with at least 0.3 m of a fine-textured coversoil; and 4) treatments 2 and 3 combined. All treatments had study plots that received either broadcast seeds or containerized transplants. Seedlings from broadcast seeds only emerged on plots that were coversoiled, but transplants survived in all treatments. Thus, coversoiling was necessary at this site for seedling germination and establishment, but survival of transplants in unaltered mine waste soil indicated that nutrient availability, soil-root contact, and water availability were sufficient for plant survival. In addition, long distance transport of seeds down stable, angle of repose slopes was not detected during the first growing season after seeding, indicating that the lack of seedlings on angle of repose slopes was not due to movement of seeds down-slope. However, coversoiling resulted in unstable slope surfaces; both erosion and soil mass wastage were observed on coversoiled treatments. Thus, although coversoiling increased establishment and survival of plants on angle of repose slopes, slope stabilization is necessary to ensure the success of revegetation efforts and to prevent the coversoil from eroding and moving downslope.
    • Rearing conditions for lambs may increase tansy ragwort grazing

      Sutherland, R. D.; Betteridge, K.; Fordham, R. A.; Stafford, K. J.; Costall, D. A. (Society for Range Management, 2000-07-01)
      Grazing by sheep is an accepted method of controlling tansy ragwort (Senecio jacobaea L.), but some flock members seldom eat it. Our objectives were to determine if pre-weaning exposure to tansy ragwort increases later consumption of the plant by lambs, and if confinement with ragwort-eating ewes after weaning facilitates ragwort eating. The sampling periods were Weeks 1, 3, and 12 following weaning. During each period grazing behavior was observed for 1-hour each day and the 24-hour reduction in ragwort volume measured on each of 4 or 5 consecutive days. Lambs exposed to ragwort before weaning removed more ragwort than ragwort-naive lambs during the first 2 sampling periods (P < 0.05). Lambs that grazed with ewes for 11 weeks following weaning ate ragwort more frequently during direct observation, than lambs without ewes during Weeks 3 and 12 (P < 0.05). The ragwort-eating of all lamb groups increased markedly between Weeks 1 and 12 (P < 0.05). This may indicate an increased ability of lambs to consume ragwort with increasing age or an acclimation period during which most lambs come to accept ragwort. Behavioral interventions aimed at increasing the consumption of weeds by lambs may need to take into account age-related differences in toxin tolerances. Exposing lambs to ragwort before weaning and grazing newly-weaned lambs with older ragwort-eating sheep after weaning may increase later ragwort-eating by lambs.
    • Supplemental barley and charcoal increase intake of sagebrush by lambs

      Banner, R. E.; Rogosic, J.; Burritt, E. A.; Provenza, F. D. (Society for Range Management, 2000-07-01)
      We evaluated the influence of supplemental barley and activated charcoal on the intake of sagebrush by lambs in individual pens. In 3 experiments, lambs were fed sagebrush (harvested and chopped to 2-3 cm) during the morning; they were fed a basal diet of alfalfa pellets in the afternoon. In the first experiment, lambs supplemented with activated charcoal + barley ate more A. tridentata ssp. vaseyana than lambs supplemented with barley (304 vs. 248 g; P = .071). A second set of experiments, which consisted of 3 trials, determined the effects of activated charcoal, barley, and subspecies of sagebrush on intake of sagebrush. Lambs supplemented with activated charcoal + barley ate more A. tridentata ssp. vaseyana (Trial 1; 292 vs. 225 g; P = .086), and more A. tridentata ssp. tridentata (Trial 2; 371 vs. 255 g; P = .031) than lambs supplemented with barley. In Trial 3, lambs supplemented with barley ate more sagebrush than lambs that were not supplemented (480 vs. 318 g; P = .0002). A third set of experiments compared activated charcoal + barley, barley, and no supplement in 2 trials. In Trial 1, lambs supplemented with activated charcoal + barley or barley generally ate more A. tridentata ssp. vaseyana than lambs not supplemented (P = .017). In Trial 2, lambs supplemented with activated charcoal + barley ate slightly more A. tridentata ssp. vaseyana than lambs supplemented with barley, and they ate substantially more than lambs not supplemented (P = .032). Collectively, the results suggest that energy from supplemental barley increased intake of sagebrush by lambs fed a basal ration of alfalfa pellets which are high in protein, and that activated charcoal played a minor role in further increasing intake of sagebrush.
    • To ranch or not to ranch: Home on the urban range?

      Liffmann, R. H.; Huntsinger, L.; Forero, L. C. (Society for Range Management, 2000-07-01)
      California ranchers in urban Alameda and Contra Costa Counties, and in rural Tehama County, were surveyed to examine effects of increasing development, land use change, and attrition of the ranching community on their commitment to ranching, and to assess land conservation program acceptability. Questions were about practices, reasons for ranching, and what influences ranching's future. Ranchers share much in common. Most enjoy ranching, "feeling close to the earth," living in a "good place for family life," and the camaraderie in the ranching community. They regularly carry out range improvements. Most believe that society is becoming "hostile to ranching." A dislike for outsider intervention and land use control prevails. Urban ranchers cared significantly less about the fate of their ranch if sold, and feared local land use planning much more. Rural ranchers overwhelmingly wanted their ranch to remain a productive ranch even if sold. No new ranchers appeared in the urban sample for the last 10 years. As urbanization proceeds, we suggest that a point is reached where ranchers recognize the social, ecological, and economic landscape as urban and see it as no longer suitable for ranching. Expecting to sell for development, and/or expecting zoning to change to allow it, becomes the rational view. Land conservation efforts, including relatively acceptable though as yet not widespread conservation easement programs, should begin before that happens.
    • Vegetation response to late growing-season wildfire on Nebraska Sandhills rangeland

      Volesky, J. D.; Connot, S. B. (Society for Range Management, 2000-07-01)
      This study examined the effects of late growing-season (September) wildfire on the subsequent production and species composition of upland Nebraska Sandhills prairie vegetation. Three paired-plots (burn and control), 0.5 ha in size were established in 1995 on sands range sites on each of 3 replications in west-central Nebraska. Soil temperature data were collected the following growing season and herbage standing crop and species composition data were collected for 3 growing seasons following the burn. During March through May of the 1996 growing season, soil temperature in the burn treatment was an average of 1.6 degrees C higher at both 15 and 30 cm depths compared to the control (P < 0.05). This small increase in spring soil temperature under the burn treatment did not appear to result in earlier growth or to increase herbage standing crop in May. Total herbage standing crop in August averaged 143, 142, and 185 g m-2 in 1996, 1997, and 1998, respectively, and did not differ between the burn treatment and control (P > 0.05). Little bluestem [Schizchyrium scoparium (Michx.) Nash] was the species most adversely affected by burning. Percentage composition by weight of little bluestem in August 1996 averaged 8% under the burn treatment compared to 47% in the control. Other species and species groups, however, were more abundant in burned plots, thus offsetting the lesser amounts of little bluestem. Little bluestem exhibited a marked recovery during the second and third growing seasons after the burn. During the third growing season, percent composition of little bluestem averaged 46% and was not different between treatments (P > 0.05). Forbs were more abundant under the burn treatment compared to the control only during the first growing season following the burn (P < 0.05).