• Applicability of the Kostiakov equation to mixed prairie and fescue grasslands of Alberta

      Naeth, M. A.; Chanasyk, D. S.; Bailey, A. W. (Society for Range Management, 1991-01-01)
      The Kostiakov equation is of interest in rangeland hydrology because it is a simple 2 parameter equation with values of constants easy to determine from measured infiltration data, and because of its reasonable fit to infiltration data for many soils over short time periods. There is, however, some controversy in the literature regarding its applicability to rangelands. The Kostiakov infiltration equation was examined to determine its suitability to characterize infiltration on mixed prairie and fescue grassland ecosystems in Alberta, Canada. The infiltration data from double ring infiltrometers fit the Kostiakov equation very well. Of 26 regressions, 10 had an R2 over 0.95 while another 8 had an R2 over 0.90. The average R2 for all data at a site was 0.931 for mixed prairie, 0.857 for parkland fescue, and 0.938 for foothills fescue grassland. Changes in antecedent soil water and different grazing regimes altered the 2 equation parameters. Intercepts consistently declined with intensity and earliness in the growing season of grazing, although there were no consistent treatment trends with grazing. The Kostiakov equation is considered a good equation for infiltration in the 3 grassland ecosystems studied. Although parameter m had a narrow range of values for all 3 ecosystems and an average value from this study could be used, parameter a limits the equation and field testing is required for its determination.
    • Cutting frequency and cutting height effects on rough fescue and parry oat grass yields

      Willms, W. D. (Society for Range Management, 1991-01-01)
      A study was made in the Rough Fescue Grasslands of southwestern Alberta to determine the yield response of rough fescue (Festuca scabrella var campestris Rydb.) and Parry oat grass (Danthonia parryi Scribn.) to 5 cutting frequencies and 3 heights over a 1-year period. The same plants were cut either 1, 2, 4, 8, or 16 times over a 16-week period beginning in mid-May, at 16-, 8-, 4-, 2-, or 1-week intervals, respectively, and at heights of either 5, 10, or 15 cm above ground level. Yield response to cutting treatments differed significantly from the flrst to the third treatment year. In the first year, rough fescue and Parry oat grass produced most forage when cut at a height of 5 cm with 1, 2, or 4 cuts. By the third year, rough fescue produced the greatest yields with a single cut after 16 weeks and Parry oat grass produced the greatest yields when cut at 10 or 15 cm at 1-week intervals. The data confirm the high sensitivity of rough fescue to grazing while the plant is growing and suggest that the greatest benefit from the Rough Fescue Grasslands may be derived by grazing in fall or winter. Summer grazing favors Parry oatgrass, which is more tolerant than rough fescue, but forage production on the grassland is reduced.
    • Economically optimal private land grazing strategies for the Blue Mountains of eastern Oregon

      Quigley, T. M.; Tanaka, J. A.; Sanderson, H. R.; Tiedemann, A. R. (Society for Range Management, 1991-01-01)
      The Oregon Range Evaluation Project implemented 3 levels of grazing management intensities (strategies) on private land pastures in the Blue Mountains of northeastern Oregon. Prior to implementing each management strategy, a coordinated resource plan was prepared and a benefit-cost analysis on each practice and pasture was performed. The goal was to achieve the largest economic return from grazing for each strategy implemented. Returns above variable costs were used to select the optimal grazing strategy for the ecosystems represented. The commodity production strategy was found to be optimal in all ecosystems over a wide range of interest rates, management costs, and beef prices.
    • Grazing impacts on litter and soil organic matter in mixed prairie and fescue grassland ecosystems of Alberta

      Naeth, M. A.; Bailey, A. W.; Pluth, D. J.; Chanasyk, D. S.; Hardin, R. T. (Society for Range Management, 1991-01-01)
      Impacts of long-term cattle grazing on litter and soil organic matter were assessed in mixed prairie, parkland fescue, and foothills fescue grasslands of Alberta, Canada. Grazing regimes were of light to very heavy intensities, grazed early, late, and continuously during the growing season. Litter and soil organic matter were sampled in 0.1-m2 quadrats and removed as live vegetation, standing litter, fallen litter, and soil organic matter. Litter and organic matter samples were air dried and sorted by size using sieves and an automatic sieve shaker. Organic carbon content was determined by thermal oxidation. Ground cover was determined using point frames, and heights of standing litter and fallen litter were measured. Heavy intensity and/or early season grazing had greater negative impacts on litter and soil organic matter than did light intensity and/or late season grazing. Under the former regimes there were significant reductions in heights of standing and fallen litter, decreases in live vegetative cover and organic matter mass, and increases in bare ground. More large particle-sized organic matter, particularly standing litter, occurred in controls than in grazed treatments since it would not be removed or trampled by grazing animals. More medium and small particle-sized organic matter occurred in grazed treatments than in ungrazed controls since vegetation likely decomposed more rapidly when it was trampled and broken down as animals grazed.
    • Response of tap- and creeping-rooted alfalfas to defoliation patterns

      Gdara, A. O.; Hart, R. H.; Dean, J. G. (Society for Range Management, 1991-01-01)
      Under grazing, creeping-rooted alfalfa (Medicago sativa L.) cultivars have been reported to be more productive and have higher survival than tap-rooted cultivars. To determine if differences in persistence could be related to response to defoliation patterns, we clipped 3 tap- and 3 creeping-rooted alfalfa cultivars. Different fractions of the total number of stems were clipped to different stubble heights every 21 days. Both tap- and creeping- rooted cultivars responded similarly to defoliation. Maximum forage production was obtained when one-third of the stems on a plant were cut back to 5 cm above the ground at each harvest. The lowest forage production was obtained when all stems on a plant were cut back to 5 cm. The most lenient defoliation (one-third of the height of one-third of the stems removed at each harvest) maximized total herbage production (forage plus stubble) but only 32% of the herbage was harvested as forage, leaving 68% as unharvested stubble. Severe defoliation every 21 days decreased the concentration of total nonstructural carbohydrate in the roots and reduced total root biomass. Thirteen alfalfa cultivars responded similarly to grazing when seeded in dense stands. The greater persistence of creeping-rooted alfalfa cultivars under grazing does not appear to be a result of greater intrinsic productivity or more rapid recovery from defoliation. The lateral spread of individual creeping-rooted plants in open stands may increase the probability that some stems will escape defoliation at each grazing; these stems then contribute to rapid recovery from grazing and to plant survival.
    • Water holding capacity of litter and soil organic matter in mixed prairie and fescue grassland ecosystems of Alberta

      Naeth, M. A.; Bailey, A. W.; Chanasyk, D. S.; Pluth, D. J. (Society for Range Management, 1991-01-01)
      Litter and organic matter accumulations can reduce soil water through interception of precipitation and subsequent evaporation of absorbed water. Interception varies with mass and water holding capacity (WHC) of litter and organic matter, and is highest from small precipitation events. WHC varies with vegetation type, which is affected by grazing regime. Thus long-term grazing could affect WHC of litter and organic matter and would be important in the hydrologic assessment of rangelands subjected to many small precipitation events throughout the growing season. The study was conducted in mixed prairie, parkland fescue, and foothills fescue grasslands in Alberta, Canada. Grazing regimes were of light to very heavy intensities, grazed early, late, and continuously during the growing season. Litter and organic matter were sorted by sieving into various sized categories. Litter-soil cores were also evaluated. WHC of litter and organic matter was lower in mixed prairie than in fescue grasslands. WHC increased with increazed particle size, being higher for roots and standing and fallen litter than for organic matter. WHC of large particle-sized material decreased with heavy intensity and/or early season grazing. WHC was affected more by intensity than season of grazing. Grazing affected WHC through species composition changes, since species have different WHC, and through trampling which affected particle size. It was concluded that litter and organic matter WHC were important in rangeland hydrologic assessments.
    • Willow planting success as influenced by site factors and cattle grazing in northeastern California

      Conroy, S. D.; Svejcar, T. J. (Society for Range Management, 1991-01-01)
      In recent years there has been an increasing emphasis on reestablishment of woody vegetation in degraded riparian zones. In this study we evaluated the influence of grazing and selected site factors on survival and leader growth of planted Geyer willow (Salix geyeriana Anderss.) cuttings. Three grazing treatments (early summer, late summer, and non-use) were evaluated on each of 3 streams in broad, low-gradient meadows with silt loam soils in the northern Sierra Nevada. The streams were perennial with terraces often 1.0 to 1.5 m above streambottom. Unrooted Geyer willow cuttings were planted to 30-cm soil depth in early May 1987 at 3 streamchannel locations (streambottom, streambank, and stream terrace) within each of the grazing treatments. Survival, associated community type, and cover class were determined for 2,700 plantings. Leader length and grazing intensity were measured for 694 surviving cuttings in 1988. Percent soil moisture and water table depth were determined for a subset of the willow cuttings. There was no significant (P>0.05) effect of grazing treatment on either willow survival or growth despite 3.5 to 5 times more defoliation use of the willow cuttings in the grazed pastures. Streamchannel location did significantly (P lesser than or equl to 0.05) affect willow survival (streambottom = 83%, streambank = 34%, and stream terrace = 3%) but not individual plant leader length. Survival of willow cuttings for Carex nebrascensis/Jancas nevadensis, bareground, Des- champsia caespitosa/Carex nebrascensis, and Artemisia sp. dominated sites was 76, 60, 44, and 2%, respectively. However, leader length was significantly (P lesser than or equal to 0.05) greater for bareground sites than for sites supporting vegetation. Cover class was not a good indicator of survival, but as might be expected from the results on the bareground sites, leader length for the 0-5% class was 1.8 times the length of the next class. There was a clear relationship between water table depth, soil moisture, and willow planting survival but not between moisture measurements and leader length. Once the water table has declined to the point that Artemisia sp. can survive on a site, the chances of successfully replanting willows are minimal. However, even during the drought years of this study (<50% of average annual precipitation) a survival rate of 60% or greater was achieved by planting into Carex nebrascensis communities or bareground in the streamchannel.