Now showing items 13949-13968 of 20709

    • Qanats in the Old World: Horizontal Wells in the New

      Pearse, C. K. (Society for Range Management, 1973-09-01)
      Horizontal wells make use of the principle of the qanat developed in Persia about 2,500 years ago and still widely used there and in other arid regions of the world. The driven horizontal well offers several important advantages over the hand dug qanat especially for livestock watering places.
    • Quaking Aspen in Utah: Integrating Recent Science with Management

      Rogers, Paul C.; St. Clair, Samuel B. (Society for Range Management, 2016-12-01)
      On the Ground • Quaking aspen is widely regarded as a key resource for humans, livestock, and wildlife with these values often competing with each other, leading to overuse of aspen in some locations and declines. • Wereview trends in aspen science and management, particularly in Utah. Historically, research conducted here holds a prestigious place in international aspen circles. • We highlight recent studies continuing the tradition to keep rangeland managers informed of important developments, focusing on aspen functional types, historical cover change and climate warming, ungulate herbivory, and disturbance interactions.
    • Qualified Men for Technicial Assistance

      Miles, W. (Society for Range Management, 1955-11-01)
    • Quality and botanical composition of cattle diets under rotational and continuous grazing treatments

      Walker, John W.; Heitschmidt, Rodney K.; D, Elino A.; Kothmann, Merwyn M.; Dowhower, Steve L. (Society for Range Management, 1989-05-01)
      Proponents of rotational grazing claim that individual animal performance in a properly managed rotational grazing (RG) treatment will be equal to or greater than that in other, less intensively managed treatments even when rate of stocking in the RG treatment is much greater. The objective of this study was to examine the effect of a heavily stocked RG treatment, at 2 stock densities, on quality and botanical composition of cattle diets. The control treatment was a moderately stocked, continuously grazed pasture. Diets were collected from all treatments on 8 dates over a 22-month period using esophageally fistulated steers. Only minor differences occurred among treatments in dietary crude protein (CP), organic matter digestibility (OMD), and botanical composition. Diet quality and species composition of diets were closely correlated with quality and availability of live herbage, which varied more among trials than among treatments. Quality and composition of diets collected during the first and last day of grazing in the RG paddocks were not different. These data support the hypothesis that installing rotational grazing at a high stocking rate does not lower diet quality and would not be expected to be a factor affecting individual animal performance.
    • Quality and persistence of forages in the Northern Great Plains

      Haferkamp, M. R.; Grings, E. E.; Heitschmidt, R. K.; MacNeil, M. D. (Society for Range Management, 2002-09-01)
      Integrating use of seedings of perennial cool-season grasses with native range is used to increase available forage and for maintaining a high plane of nutrition for grazing livestock. Our goal was to evaluate performance of yearling cattle and stand persistence of 3 released wheatgrass cultivars. Twice replicated 3-ha pastures were seeded to 'Rosana' western wheatgrass [Pascopyron smithii (Rydb.) A. Love], 'Luna' pubescent wheat-grass [Elytrigia intermedia (Host) Nevski], and 'Hycrest' crested wheatgrass ([Agropyron cristatum (L.) Gaertn.] ssp. desertorum (Fisch. ex Link) A. Love) in autumn 1994. Yearling steers (n = 8) grazed from 9 May to 12 June 1997 and 24 April to 15 June 1998. Yearling heifers grazed from 27 April to 18 June 1999. Hycrest produced the largest herbage standing crop in spring 1997 (912 kg ha(-1)) and 1998 (1,223 kg ha(-1)) (P < 0.05), but by spring 1999 standing crops averaged 656 kg ha(-1), and cultivars were not significantly different. Digestible organic matter standing crop did not differ among pastures of seeded species, but declined (P < 0.05) from May to June each year. Crude protein standing crop varied among cultivars (P < 0.05) in April and May 1998 and May 1999; however, no clear trends emerged. Crude protein standing crops consistently declined from April-May to June. Average daily gains were similar among cultivars in 1997, but greater (P < 0.05) on Hycrest (1.28 kg day(-1)) than Rosana (1.03 kg day(-1)) in 1998. Gains on Hycrest (0.74 kg day(-1)) and Rosana (0.78 kg day(-1)) were greater (P < 0.05) than on Luna (0.52 kg day(-1)) in 1999. These findings show in some years, Hycrest provided more forage in spring than Rosana, and will allow an increase in livestock numbers. Based on the encroachment of invading species, persistence of Luna is marginal of the 335-mm precipitation zone in the Northern Great Plains.
    • Quality and Yield of Forage as Affected By Chemical Removal of Blue Oak

      Murphy, A. H.; Crampton, B. (Society for Range Management, 1964-05-01)
    • Quality Assurance of Ultrafiltered Bone Dating

      Brock, Fiona; Bronk Ramsey, Christopher; Higham, Thomas (Department of Geosciences, The University of Arizona, 2007-01-01)
      Ultrafiltration of bone collagen provides a method of purification that can be very effective in reducing environmental contamination from soil-derived amino acids as well as removing degraded collagen or other short-chain proteins. The Oxford Radiocarbon Accelerator Unit (ORAU) first implemented ultrafiltration in the pretreatment of bone material for accelerator mass spectrometry (AMS) radiocarbon dating in 2000. However, the filters themselves contain carbonaceous material, and thus stringent quality control is required to demonstrate that this does not affect the accuracy of the dating. Here, we present quality assurance data from the bone pretreatment and dating program at ORAU, including dates on known-age and background-age bones over a range of sample sizes, and measurements of residual carbon contamination present in the filters after cleaning.
    • Quality Controlled Radiocarbon Dating of Bones and Charcoal from the Early Pre-Pottery Neolithic B (PPNB) of Motza (Israel)

      Yizhaq, Meirav; Mintz, Genia; Cohen, Illit; Khalaily, Hamudi; Weiner, Steve; Boaretto, Elisabetta (Department of Geosciences, The University of Arizona, 2005-01-01)
      Radiocarbon dating of early Pre-Pottery Neolithic B (PPNB) deposits at the site of Motza, Israel, was achieved by first prescreening many charcoal and bone samples in order to identify those that are in the most suitable state of preservation for dating. For assessing bone preservation, we determined the collagen contents, and by infrared spectroscopy the collagen purity. The collagen samples of the best preserved bones were then further characterized by their C/N ratios and amino acid compositions. Prescreening of the charcoal samples involved monitoring the changes in infrared and Raman spectra during the acid-alkali-acid treatments. In some samples, we noted that the clay content increased with additional alkali treatments. These samples were rejected, as this could result in erroneous dates. No differences were observed in the 14C dates between charcoal and bone collagen samples. The dates range from 10,600-10,100 cal BP, which is consistent with dates for the early PPNB from other sites. This is of much interest in terms of better understanding where and when domestication of animals began in this period, and how agriculture spread throughout the Levant.
    • Quality Cotton

      Ray, Howard E.; Briggs, Robert E.; Agronomy Department (College of Agriculture, University of Arizona (Tucson, AZ), 1959)
    • Quality of Forage and Cattle Diets on the Wyoming High Plains

      Hart, R. H.; Abdalla, O. M.; Clark, D. H.; Marshall, M. B.; Hamid, M. H.; Waggoner, J. W. (Society for Range Management, 1983-01-01)
      Diets of cattle grazing crested wheatgrass [Agropyron desertorum (Fisch.) Schult.] or native range pastures and major forage species in these diets were analysed for crude protein (CP), acid and neutral detergent fiber (ADF and NDF), lignin, and in vitro dry matter disappearance (IVDMD) 1975-1978. Objectives were to determine (1) rate of change in forage quality, (2) effect of weather on rate of change, and (3) degree of selection for diet quality by cattle. CP of 6 forage species declined .03-.23 percentage points/day, while IVDMD declined .06-.90 points/day. CP and IVDMD of western wheatgrass (Agropyron smithii Rydb.), blue grama [Bouteloua gracilis (H.B.K.) Lag. ex Steud.], and scarlet globemallow [Spahaeralcea coccinea (Pursh.) Rydb.] were high in spring, while ADF, NDF, and lignin were low, but quality of grasses decreased much faster than that of the forb. Quality of needleandthread (Stipa comata Trin. & Rupr.) was lower than that of the other two grasses in spring, but CP declined more slowly then, while IVDMD declined at the same rates as that of blue grama and western wheatgrass. Quality of sedges (Carex spp.) was similar to that of western wheatgrass and blue grama in spring, but CP decreased faster while fiber components increased slower than those of grasses. CP of western wheatgrass and blue grama was increased by abundant spring rainfall, while that of blue grama increased after heavy summer rains. As the season progressed, cattle on range selected diets higher in crude protein and lower in cellulose than expected on the basis of botanical composition of the diet and composition of individual species. Quality of forage consumed increased markedly in mid-July when immature blue grama replaced needleandthread in the diet. Quality of crested wheatgrass declined faster than that of range grasses, although it was higher early in the spring. Diets of cattle on crested wheatgrass pasture in early spring were lower in quality than clipped crested wheatgrass, because of consumption of standing dead material, but diets were higher in quality than clipped grass in late spring.
    • Quality of forage stockpiled in Wisconsin

      Hedtcke, J. L.; Undersander, D. J.; Casler, M. D.; Combs, D. K. (Society for Range Management, 2002-01-01)
      Stockpiling forage is a commonly used method to extend the grazing season in the southern U.S.A. However, there is little data on stockpiled forage in the upper Midwest. This study was conducted to determine the quality changes of 7 stockpiled cool-season grasses [early and late maturing orchardgrass, Dactylis glomerata L., quackgrass, Elytrigia repens (L.) Desv. Ex. Nevski, reed canarygrass, Phalaris arundinacea L., smooth bromegrass, Bromus inermis Leyss., tall fescue, Festuca arundinacea Schreb., and timothy Phleum pratense L.], with and without N fertilizer, in Wisconsin. Forage was sampled at 3 offseason dates at 3 sites. To determine if N improved forage quality, 4 N-fertilizer treatments were imposed: 0 or 67 kg N ha(-1) applied at start of stockpiling and 2 treatments totaling 168 kg N ha(-1) applied in the fall and spring. Over winter, crude protein (CP) decreased from 116 to 107 g kg(-1), neutral detergent fiber (NDF) increased from 594 to 667 g kg(-1), acid detergent fiber (ADF) increased from 367 to 435 g kg(-1), and in vitro organic matter digestibility (IVOMD) fell from 734 to 655 g kg(-1). Nitrogen fertilizer improved CP in most environments but generally did not affect IVOMD, NDF, or ADF. Smooth bromegrass and quackgrass ranked highest in CP concentration and tall fescue ranked lowest. Timothy and late-maturing orchardgrass ranked highest in IVOMD while quackgrass and reed canarygrass consistently ranked lowest. Quality of all stockpiled forage studied can maintain livestock such as beef cattle or dry dairy cows over winter if the forage is accessible and adequate animal stocking density is maintained.
    • Quality of Hay from CRP Lands in North Dakota

      Sedivec, Kevin; Soiseth, Charlie (Society for Range Management, 1998-06-01)
    • Quality of Water for Livestock in Man-made Impoundments in the Northern High Plains

      Rumble, M. A. (Society for Range Management, 1985-01-01)
      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.
    • Quality Seed is Your Best Buy

      Dennis, R. E.; Department of Agronomy (College of Agriculture, University of Arizona (Tucson, AZ), 1962)
    • Quality, Yield, and Survival of Asiatic Bluestems and an Eastern Gamagrass in Southern Illinois

      Faix, J. J.; Kaiser, C. J.; Hinds, F. C. (Society for Range Management, 1980-09-01)
      Six Asiatic bluestems (Bothriochloa spp.) B. caucasica, cv. Caucasian, B. ischaemum var. ischaemum cv. Plains, and 4 experimental strains of B. Intermedia × B. ischaemum (B,L,LL, and T), and an Eastern gamagrass (Tripsacum dactyloides cv. PM-K-24) were grown in southern Illinois on a Typic Fragiudalf soil common to the Central U.S. Transitional Zone. The grasses were evaluated from 1975 through 1977 for yield, crude protein (CP), and in vitro digestibility (IVD) to determine their potential as alternatives to "summer dormant" tall fescue (Festuca arundinaceae) in southern Illinois. Average seasonal dry matter yields ranged from 10 to 15 metric tons per hectare. Eastern gamagrass was slower to establish than the bluestems, but after the first production year it was higher yielding than the bluestems. Forage CP and IVD averaged near 11 and 50%, respectively, over the 3-year period. There was little difference between the grasses for CP, but IVD of Caucasian bluestem was significantly lower than that of the other bluestems and Eastern gamagrass. All the grasses survived the three winters that yield and quality data were taken, but in two subsequent severe winters only Caucasian bluestem and the Eastern gamagrass were winter hardy.
    • Quantification and simulation of soil water on grazed fescue watersheds

      Chanasyk, David S.; Mapfumo, Emmanuel; Willms, Walter D.; Naeth, M. Anne (Society for Range Management, 2004-03-01)
      A 2-year study was conducted at the Agriculture and Agri-Food Canada Stavely Range Substation, Alberta. The objective was to quantify and simulate the soil water status of small grassland watersheds under 3 grazing intensities and 4 topographic positions. The grazing treatments were ungrazed (or control), heavy (2.4 AUM ha-1) and very heavy (4.8 AUM ha-1) grazing and the topographic positions were upperslope, midslope, lowerslope and 5 m away from the collector drain. Moisture readings were taken every 2 weeks between spring and fall using a CPN 503 moisture neutron probe. Readings were taken at the soil surface and at 15-, 25-, 35-, 45- and 55-cm depths. Total annual precipitation in 1998 and 1999 was 648 and 399 mm, respectively. In both years grazing treatments did not affect total soil water in the 0-50 cm (TSW50) depth interval for the upper, middle and lower slope positions, but TSW50 close to the collector drain was significantly (P ≤ 0.05) greater for the heavy grazed compared to the very heavy grazed treatment. Within each grazing treatment, TSW50 differences among slope positions occurred mainly under the heavy grazed treatment. Simulation of soil water at each soil depth and watershed was conducted using the Versatile Soil Moisture Budget Model (VB2000). Statistical and graphical evaluations of the model results were conducted using the volumetric soil water data collected for 1998 and 1999. The statistics determined included average error (AE), root mean square (RMS), coefficient of residual mass (CRM), modeling efficiency (EF) and coefficient of determination (CD). All statistics varied with each soil depth and watershed, indicating the transient nature of the data. This is reflected in the mostly negative CRM values, which ranged between -1.0 and 0.16. Overall model fitting to the whole data for all depths, watersheds and years gave values of CRM = -0.08 and EF = 0.19, indicating a slight over-prediction by the model. Spatial variation due to presence of rocks or cracks and averaging across slopes may have partly contributed to the discrepancies between model results and observed data.
    • Quantifying Background Components of Low-Level Gas Proportional Counters

      Theodórsson, Páll (Department of Geosciences, The University of Arizona, 1992-01-01)
      I discuss background components of low-level gas proportional counters and show how each component can be estimated based on available data. For more reliable background analysis, further studies are suggested. Based on new information, a generation of low-level gas proportional counting systems for radiocarbon dating may emerge with lower and more predictable background.
    • Quantifying Declines in Livestock Due to Land Subdivision

      Boone, Randall B.; BurnSilver, Shauna B.; Thornton, Philip K.; Worden, Jeffrey S.; Galvin, Kathleen A. (Society for Range Management, 2005-09-01)
      In Kajiado District, Kenya, ranches held communally by Maasai are being subdivided into individually owned parcels. Livestock owners know that herds on parcels that are too small cannot be viable, but the decline in the capacity of parcels to support livestock has not been quantified. We used ecosystem modeling to represent the effects of subdivision as Maasai group ranches were divided into 196, 10, 5, 3, and 1 km2 parcels. Within the spatially explicit, process-based SAVANNA ecosystem model, we used maps that constrained the movements of livestock to be within parcels. We also modeled cooperative grazing associations, giving groups of herders access to parcels composed of dispersed or contiguous 1 km2 parcels. Vegetatively productive areas had higher carrying capacities when isolated because resident animals did not compete with animals moving in seasonally from other areas. In a ranch of low but heterogeneous productivity, we saw a steady decline in capacity under subdivision, until 25% fewer livestock could be supported on the ranch of 1 km2 parcels relative to the intact ranch. On a ranch with both low productivity and heterogeneity, 20% fewer livestock were supported when parcels were still 10 km2. The most productive ranch studied saw small population changes with subdivision. Participation in grazing associations was helpful in the ranch intermediate in productivity and heterogeneity, but not other ranches. Subdivision of Kajiado lands might be inevitable, but our results show the relative benefits to stakeholders if land owners and policy makers act to maintain open or flexible access to individually held parcels.  
    • Quantifying hydrogen-deuterium exchange of meteoritic dicarboxylic acids during aqueous extraction

      Fuller, M.; Huang, Y. (The Meteoritical Society, 2003-01-01)
      Hydrogen isotope ratios of organic compounds in carbonaceous chondrites provide critical information about their origins and evolutionary history. However, because many of these compounds are obtained by aqueous extraction, the degree of hydrogen-deuterium (H/D) exchange that occurs during the process needs to be quantitatively evaluated. This study uses compound- specific hydrogen isotopic analysis to quantify the H/D exchange during aqueous extraction. Three common meteoritic dicarboxylic acids (succinic, glutaric, and 2-methyl glutaric acids) were refluxed under conditions simulating the extraction process. Changes in delta-D values of the dicarboxylic acids were measured following the reflux experiments. A pseudo-first order rate law was used to model the H/D exchange rates which were then used to calculate the isotope exchange resulting from aqueous extraction. The degree of H/D exchange varies as a result of differences in molecular structure, the alkalinity of the extraction solution and presence/absence of meteorite powder. However, our model indicates that succinic, glutaric, and 2-methyl glutaric acids with a delta-D of 1800 would experience isotope changes of 38 ppm, 10 ppm, and 6 ppm, respectively during the extraction process. Therefore, the overall change in delta-D values of the dicarboxylic acids during the aqueous extraction process is negligible. We also demonstrate that H/D exchange occurs on the chiral alpha-carbon in 2-methyl glutaric acid. The results suggest that the racemic mixture of 2-methyl glutaric acid in the Tagish Lake meteorite could result from post-synthesis aqueous alteration. The approach employed in this study can also be used to quantify H/D exchange for other important meteoritic compounds such as amino acids.
    • Quantifying spatial heterogeneity in herbage mass and consumption in pastures

      Hirata, M. (Society for Range Management, 2000-05-01)
      A sward-based technique for quantifying the spatial heterogeneity in herbage mass and consumption was developed and tested in a bahia grass (Paspalum notatum Flügge) pasture grazed by cattle. For five, 2-day grazing periods from May to October, pre- and post-grazing herbage masses were nondestructively estimated with an electronic capacitance probe at 182, 50x50 cm locations along 2 permanent line transects. At the same time, undisturbed herbage accumulation during grazing was measured inside exclosures and the results used to estimate accumulation under grazing at each location. Estimation of herbage mass was relatively good; R2= 0.88 to 0.98. Spatial heterogeneity in herbage mass and the stability of the spatial pattern were well quantified. The pattern of spatial heterogeneity observed early in the grazing season remained quite stable for 5 months until the late grazing season. Spatial heterogeneity in the rate of defoliation was also well quantified in spite of some negative values. The technique is of potential value for quantifying the spatial hetero-geneity in herbage mass and consumption by animals in grazed pastures, though further studies are necessary for testing the applicability of the technique to pastures of other plant species or of multiple species.