Now showing items 1-20 of 24

• #### Vegetational Traits of Patch-grazed Rangeland in West-Central Kansas

Indices of vegetation abundance, composition, and grazing were monitored for the grazing seasons of 1980-81 at Hays, Kans., in 2 pastures. One pasture was moderately grazed with yearling steers season-long, while the other was triple-stocked for only the first half of the season. Some areas were grazed repeatedly throughout the grazing seasons, resulting in overgrazed patches, which increased in number as seasons progressed. By the end of each grazing period, more than 70% of each pasture was grazed, but only 23-56% of the areas consisted of overgrazed patches depending on the year and treatment. Grazing treatment also influenced whether the locations of patches remained the same from year to year. Species composition of overgrazed patches was different from the surrounding vegetation, but soil properties were not.
• #### Technical Notes: A Tool for Sampling Flat Jointed Opuntia

A section of automobile exhaust pipe was machined to produce a tool for sampling prickly pear. The tool provides a method to quickly and easily remove a section of the cladophyll. This method produces samples with a uniform surface area.
• #### Stand Age, Precipitation, and Temperature Effects on Forage Yield

The effects of seasonal distribution of precipitation on forage yield are often confounded by stand age. Forage yields of Russian wildrye (Psathyrostachys junceus), green needlegrass (Stipa viridula), crested wheatgrass (Agropyron desertorum), and intermediate-pubescent wheatgrass (Agropyron intermedium-trichophorum) were determined from 6 separate studies, each of 6 years duration, from 4 locations in the northern Great Plains. Stepwise multiple regression showed that forage yield of all 4 species was significantly (P<0.01) related with April and May precipitation and stand age. Forage yield of Russian wildrye was significantly (P<0.05) related with April mean monthly temperature and degree days (accumulation of daily mean air temperature above a given threshold temperature) accumulated until the end of May or June; however, yields of the other 3 species were not significantly related with April, May, or June mean monthly temperatures nor degree days accumulated until the end of May or June. The highest forage yield per centimeter of precipitation occurred either the second or third year after establishment; then yield decreased asymptotically and by year 5 or 6 was only 75% of maximum for green needlegrass and 40-50% for the other grasses. Economic evaluation of seeding forages must include the influence of stand age on forage yield.
• #### Some Growth Characteristics of Four Old World Bluestems

The growth dynamics of 4 Old World bluestem (Bothriochloa spp.) accessions were monitored in the field by periodic harvests of the aboveground biomass components (leaf blades, leaf sheaths plus enclosed stems, exerted stems plus inflorescences) during 2 growth cycles from April to September 1982. The first cycle extended from spring growth initiation (15 March) through flowering (6 July). The second cycle was initiated following the completion of the first by mowing the plants to a 50-mm stubble height and ended at flowering stage (20 September). Growth conditions during the first cycle were considered near optimum when precipitation was 1.71 of the long term mean and soil moisture averaged about 0.29 by volume. Temperatures during the second cycle were approximately 10 degrees C higher than during the first and precipitation was only 0.18 of normal. Soil moisture declined linearly throughout the second cycle and all accessions exhibited visual symptoms of drought stress. There were significant differences among accessions for most of the experimental parameters and accession ranking changed with the imposition of drought stress during the second cycle. Accessions with high relative growth rates were least tolerant of drought stress. Severe defoliation by clipping at the start of cycle 2 revealed 2 regrowth patterns which suggested potential differences in grazing tolerance. Two accessions tended to optimize canopy development by maximizing leaf area index while minimizing biomass and nitrogen investment per unit leaf area. The remaining 2 accessions produced fewer leaves with more investment per leaf. Lower relative growth rates of biomass and the ability to optimize canopy development following defoliation may result in a more stable forage source through time. Plants with these characteristics may not be top producers during periods of favorable growing conditions, but will likely maintain a level of performance under stress which compares more favorably with pre-stress performance.
• #### Response to Tebuthiuron by Utah Juniper and Mountain Big Sagebrush Communities

The herbicide tebuthiuron was applied aerially in replicated parallel strips at rates of 0, 1.3, 2.0, and 2.7 kg/ha a.i. (active ingredient) in 40% pellets on a Utah juniper stand, and at rates of 0, 0.6, 1.0, and 1.3 kg/ha a.i. in 10% pellets on a mountain big sagebrush stand. Crown kill on Utah juniper was nearly 100% at application rates of 2.0 kg/ha or greater. Control of mountain big sagebrush was obtained at rates of 0.6 kg/ha and above. Antelope bitterbrush, hairy low rabbitbrush, and gray horsebrush responded to the herbicide similarly to Utah juniper. Rubber rabbitbrush was not controlled by tebuthiuron. Total understory production had changed little 3 years after application, although compensating decreases in production of perennial plants and increases in production of annual grasses occurred.
• #### Response of an Irrigated Cool- and Warm-Season Grass Mixture to Nitrogen and Harvest Scheme

Maintaining a mixture of cool-and warm-season grasses under intensive management for season-long production is difficult, due to species shifts, especially to a dominance of cool-season grasses when heavy amounts of nitrogen (N) fertilizer are used. The objective of this study was to determine if high forage yields could be produced season long while maintaining a desirable balance of warm-and cool-season grasses. The study was conducted near Mead, Nebraska on a Sharpsburg silty clay loam (Typic Argiudoll). An irrigated mixture of 3 warm-season grasses and 1 cool-season grass, big bluestem (Andropogon gerardii Vitman), switchgrass (Panicum virgatum L.), and indian-grass [Sorghastrum nutans (L.) Nash] and smooth brome (Bromus inermis Leyss.) was fertilized at low (150 kg/ha), medium (250 kg/ha) and high (350 kg/ha) rates of N in split applications. Three harvest schemes were designed to either produce high quality forage or to maximize yield. Herbage yields showed a quadratic response with N level. A late May/mid July harvest scheme for the first and second cuttings did not produce as much forage as late May/late August or early June/late August harvest schemes. Population of smooth brome and other cool-season grasses declined with the higher N rates. Populations of warm-season grasses were not greatly affected by N level. Density of smooth brome increased under all harvest scheme treatments and the highest increase for other cool-season grasses was with a May 24/July 13 harvest scheme. Warm-season grasses maintained a steady density over the 3 years. Forage was produced from early May until late summer with an irrigated cool- and warm-season mixture. Fall production of smooth brome was minimal, although stand was generally maintained. Nitrate N accumulated in the soil under the medium and high N treatments.
• #### Quality of Water for Livestock in Man-made Impoundments in the Northern High Plains

Twenty-seven water quality parameters were measured in coal surface mine impoundments, bentonite surface mine impoundments, and livestock ponds in the Northern High Plains. Most impoundments were safe for use as a source for livestock drinking water. Eight water quality parameters were different (alpha is lesser than or equal to 0.05) among the types of impoundments. Sulfate concentrations in some coal and bentonite surface mine impoundments were higher than recommended for safe livestock use. Total dissolved solids in bentonite surface mine impoundments may be higher than considered safe. Lead concentrations in some coal surface mine impoundments and livestock ponds exceeded the recommended safe levels for livestock drinking water.
• #### Proline Concentrations in Water Stressed Grasses

This study was conducted to screen several warm- and cool-season grasses for their proline-accumulating ability under water stressed conditions in the growth chamber. Plants of Old World bluestems (Bothriochloa spp.), tall fescue (Festuca arundinacea), western wheatgrass (Agropyron smithii) and weeping lovegrass (Eragrostis curvula) were subjected to water stress conditions at the vegetative stage. Water stressed plants exhibited a significantly greater (P<.05) increase in proline concentration than the non-stressed and the stress relieved plants. There was also a significant difference (P<.01) in the proline-accumulating ability of various species. An interdependency was observed between leaf water potential and proline concentration in all the species under water-stressed conditions.
• #### Prescribed Burning in the Loess Hills Mixed Prairie Southern Nebraska

Abused rangelands dominated by introduced cool-season grasses and warm-season shortgrasses are common over much of the Mixed Prairie. Native decreaser species are primarily warm-season grasses and are present at only insignificant levels on abused rangeland in the Loess Hills of southcentral Nebraska. A single, late-spring, prescribed fire was evaluated as a method of improvement. The study area consisted of 3 tracts of plots located on Holdrege silt loam soil (Typic Argiustall) with an average annual precipitation of 550 mm. The vegetation on the tracts was in low range condition, with cool- and warm-season components being present in varying proportions on all tracts. In general, the dominant cool-season species were Kentucky bluegrass (Poa pratensis) and annual bromes (Bromus spp.), and the dominant warm-season species were blue grama (Bouteloua gracilis) and buffalograss (Buchloe dactyloides). Burning reduced the basal cover and herbage yields of cool-season species. This favored the warm-season component. The increaser short grasses generally exhibited higher herbage yields and basal cover on burned as compared to unburned plots. These results indicate that a single, late-spring, prescribed burn may have a limited potential as a range improvement practice in the Loess Hills of south central Nebraska.
• #### Nutritive Value of Tree Leaves in the Kansas Flint Hills

Leaves from bur oak (Quercus macrocarpa Michx.), a bur oak hybrid (bur $\text{oak}_{{\rm H}}$), red elm (Ulmus rubra Muhl.), Osage orange (Maclura ponifera (Raf.) Schneid.), and cottonwood (Populus deltoides Marsh.) were analyzed for crude protein, in vitro dry matter digestibility (IVDMD), and tannic acid equivalents (TAE) from mid September through late October during 1979 and 1980. Samples were taken biweekly from the trees and from the ground after leaf fall. Cottonwood was significantly lower over the season in crude protein than all other species except bur oak. Crude protein content declined with advancing season in all species although not significantly. Leaves on the trees were considerably higher in crude protein than True Prairie understory vegetation or leaves on the ground although leaves on the ground had equal or greater crude protein levels than True Prairie understory vegetation. Sample date and species significantly affected digestiblity. Digestiblity generally increased during middle sample periods and returned to initial levels in late October. Averages over all dates showed digestibility of Osage orange > cottonwood > red elm > bur oak(H) > bur oak. Leaves on the tree were generally more highly digestible than those on the ground. Red elm, Osage orange and cottonwood leaves on the tree were more digestible than True Prairie understory vegetation. Osage orange and cottonwood leaves on the ground were more digestible than True Prairie understory vegetation. Tannic acid equivalents of bur oak(H) > oak > red elm and cottonwood > Osage orange. Tannic acid equivalents generally increased during the middle sample periods and returned to initial levels in late October. There were no TAE differences between leaves on the trees and those on the ground. Overall quality ranking based on the constituents measured showed Osage orange and red elm to be the highest quality leaves of the group, bur oak poorest, and cottonwood and bur oak(H) intermediate. On the basis of these limited tests, Osage orange and red elm would provide the best roughage source in times of severe drought or as a roughage substitute in cattle finishing rations.
• #### Nutritional and Physical Attributes of Seeds of Some Common Sagebrush-steppe Plants: Some Implications for Ecological Theory and Management

A study was conducted to identify seed attributes which might influence granivore preferences. Physical and chemical characteristics were estimated for seeds of 7 common sagebrush-steppe species (Artemisia tridentata, Bromus tectorum, Oryzopsis hymenoides, Pascopyrum smithii, Purshia tridentata, Stipa comata and Stipa viridula) and 1 sacrifice food species (Panicum miliaceum). Seed weights and caloric contents were determined, as well as % composition contributed by 5 organic, 3 inorganic and 5 synthetically defined fractions (including crude protein, solvent extract, structural and soluble carbohydrates and lignin). Results indicate that % soluble carbohydrate may be a good predictor of granivore seed preference. The generality of this or any other predictor is unknown, since sufficiently detailed seed attribute data are unavailable for most species. For management scenarios involving seeds subject to predation, such data would help effectively translate ecological understanding of granivory into more efficient management practices.
• #### Nutrient Removal Rates from Ruminoreticula of Cattle Grazing Kansas Flint Hills Range

A Hereford steer and heifer were used to compare rumen removal rates of forage nutrients from Kansas Flint Hills range over a 2-year period. Rumens were emptied after an overnight fast and the contents sampled, weighed, and returned to the rumen. The cattle were then fed a known amount of range forage and fasted for 12 hours, at which time the rumen evacuation procedure was repeated. Removal rate calculations were based on change in rumen contents during the 12-hour fast. All nutrients studied passed the rumen more rapidly during spring and summer months than fall and winter months. Fibrous fractions were removed more rapidly than cell solubles and crude protein, which may indicate that optimum utilization of native Flint Hills range forage is not being achieved. Methods which increase microbial attack of plant cell wall contents may significantly improve livestock production on native rangeland.
• #### Navajo Use of Mixed-breed Dogs for Management of Predators

Seventy-two Navajo ranchers were questioned about the role of mixed-breed dogs with their flocks. Navajos call their dogs "sheep dogs" but, unlike sheep dogs used by other ranchers to assist in herding and moving the flocks, Navajo dogs function primarily as guardians of sheep and goats to whom they have developed social bonds. This attraction is a result of raising dogs essentially from birth in visual, olfactory, auditory, and tactile association with sheep and goats. A minimum of handling of pups reduces the likelihood that they will bond strongly to humans. Mixed-breed dogs of the Navajo appear to exhibit all behavioral traits believed to be important in protecting flocks from predators, especially coyotes: they are attentive, defensive, and trustworthy. If ranchers choose to employ dogs, the rather simple Navajo recipe for training may serve them well. Mixed-breed dogs could be quickly deployed in a variety of ranching situations to help reduce predation on livestock.
• #### Mechanical renovation of shortgrass prairie for increased herbage production

A study to determine the effects of single ripping, double ripping, and contour furrowing treatments was conducted on shortgrass rangeland in southeastern Wyoming from 1979-1982. The mechanical treatments changed species composition and increased total forage production over the control. Western wheatgrass (Agropyron smithii Rydb.) exhibited increased production on the treated areas compared to the control. Blue grama [Bouteloua gracilis (H.B.K.) Lag. ex Griffiths] production was significantly lower on the double ripping (1981 and 1982) and the contour furrow (1981) treatments than on the control. Needle-and-thread (Stipa comata Trin. & Rupr.) exhibited an increasing trend on the single and double ripping treatment over the control treatment all 4 years. Forbs also showed his trend in 1979, 1980 and 1981 on all renovation treatments, however little difference in forb production was evident in 1982. Total production differences were the greatest in the first year of renovation (1979) and in 1980 when the annual precipitation was below the long-term average. Increased livestock carrying capacities would result in payback of the renovation costs in 4 years.
• #### Investment Rationale for Range Improvement Practices in Eastern Montana

Evidence suggests that the range livestock industry in the Northern Great Plains is not as productive as it should be. Ranchers are not readily adopting the range improvement practices that researchers recommend. Therefore, an economic survey of eastern Montana ranchers was conducted to evaluate the current status of range improvement practices. Specific objectives were to determine: (1) if range improvement investments were influenced by ranch size; (2) the kinds of range improvements that were being implemented; (3) the areas where additional research was needed in range improvements; and (4) if stocking rates were influenced by ranch size. It was determined that a majority of the ranchers had purchased equipment and invested in additional water developments, fencing, and other structural improvements during the previous five-year period. A much smaller percentage had invested in seeded pastures, contour furrows, fertilizer, and other nonstructural improvements. Although small ranches had more range improvements developed per unit area, large ranches (401 animal units or more) were investing in range improvements more frequently than smaller ranches. Questionnaires returned from 568 ranchers indicated that research on range improvement practices should emphasize range seeding. Stocking rate on rangeland was not influenced by ranch size.
• #### Influence of Season and Intensity of Defoliation on Bluebunch Wheatgrass Survival and Vigor in Southern British Columbia

Bluebunch wheatgrass (Agropyron spicatum Pursh) Scribn. & Smith) response to various clipping regimes which incorporated different times, frequencies, and intensities of defoliation was examined in southern British Columbia. The experiment was repeated for 3 consecutive years at a low (296 m) and a high (1,112 m) elevation site. Plant survival and vigor was evaluated the summer following defoliation. Greatest injury was incurred by treatments involving defoliation to a 5-cm stubble height from mid April to the end of May or from early May to mid June at the low and high elevation sites, respectively. Reduced injury occurred from treatments which left 10 or 15-cm stubble heights or which ceased defoliation earlier in the season. No appreciable damage was incurred by fall clipping to 5 cm or by season-long defoliation to 20 cm. Injury resulting from spring plus fall as compared to spring only defoliation was inconsistent. Greatly reduced injury for many treatments at the low elevation site in one year was attributed to unusually warm spring temperatures and attendant rapid spring growth.
• #### Impact of SO2 Exposure on the Response of Agropyron smithii to Defoliation

Agropyron smithii populations exposed to 3 controlled SO2 concentrations were defoliated either once or twice during the growing season at a light and a heavy intensity. The intensity and frequency of defoliation were most influential in determining growth and tillering responses. Defoliating twice, at either intensity, had a large negative impact on plant growth whereas compensatory growth occurred after defoliating once at either intensity. Sulfur dioxide alone had no significant effect on biomass or the number of tillers, even though sulfur accumulated approximately in proportion to exposure concentration. Sulfur dioxide exposure with the additional influence of defoliation affected both the regrowth of A. smithii in terms of biomass and tiller numbers and forage sulfur concentration. Decreased plant growth in response to SO2 plus defoliation was dependent on defoliation frequency, whereas the effect of SO2 plus defoliation on plant sulfur concentration was positive and negative and depended on a complex interaction of SO2 concentration and defoliation frequency and intensity. The results are discussed in relation to the short- and long-term compensatory growth potential of a system simultaneously exposed to grazing and air pollution and the potential effect on consumers.
• #### Factors Influencing Patterns of Cattle Grazing Behavior on Shortgrass Steepe

Factors influencing distribution of free-roaming cattle were studied on shortgrass steppe in northeastern Colorado. Spatial units selected for grazing were plant communities (soil-plant associations) and a stock-watering area. Regression models of grazing patterns were derived for growing- and dormant-season grazing patterns. Seasonal-grazing distribution was correlated with proximity to water (1/distance) and site-quality indicators. Internal validation of seasonal-grazing models indicated a good fit of predicted to observed patterns. Because ad hoc regression models lack wide applicability, relationships between spatial preference and vegetation properties were investigated. Combined relative measures of forage quality and quantity were good predictors of community preference. Measures of relative biomass or frequencies of forage species were poor predictors of spatial preference. The high correlation between preference and properties of plants composing the bulk of the diet suggests an interaction between diet selection and selection of grazing areas. The highest correlation occurred between relative community preference and relative aboveground standing nitrogen (crude protein).
• #### Evaluation of Pedometers for Measuring Distance Traveled by Cattle on Two Grazing Systems

The precision and accuracy of pedometers for measuring distance traveled by cattle on production size grazing systems were studied. Pedometer calibration factors were similar among cattle, but varied because of differences in the sensitivity of pedometers to movement and/or the tightness of the case around the animal's leg. Adjusting pedometer readings by their individual calibration factor provided a precise and accurate measure of travel distance. Cattle on a short duration grazing system tended to walk farther, and travel distance was more variable than with animals on a continuous grazing system.