• Effects of Planting Depth and Soil Texture on the Emergence of Four Lovegrasses

      Cox, J. R.; Martin, M. H. (Society for Range Management, 1984-05-01)
      We studied the emergence of 4 lovegrass accessions planted at 0.0, 0.5, 1.0, 1.5, and 2.0 cm depths in Pima silty clay loam, Sonoita silty clay loam, and Comoro sandy loam soils in a greenhouse. Catalina boer lovegrass (Eragrostis curvula var. conferta Nees) emergence was superior to A-84 boer lovegrass, A-68 Lehmann lovegrass (Eragrostis lehmanniana Nees) and Cochise lovegrass (Eragrostis lehmanniana Nees X E. trichophera Coss & Dur.) in all soils and at all depths. Approximately 75% of the radicles of germinating Lehmann and A-84 boer lovegrass seeds failed to penetrate the surface of the 3 soils when surface sown. Lehmann lovegrass seed planted below the surface failed to emerge in the 3 soils.
    • Effects of Livestock Grazing on Infiltration Rates, Edwards Plateau of Texas

      McCalla, G. R.; Blackburn, W. H.; Merrill, L. B. (Society for Range Management, 1984-05-01)
      The influence of short duration grazing (SDG), moderate continuous grazing (MCG), heavy continuous grazing (HCG), and grazing exclusion on infiltration rates of midgrass and shortgrass-dominated communities was evaluated over a 20-month period on the Texas Agricultural Research Station, located near Sonora in the Edwards Plateau, Texas. A combination of cattle, sheep, and goats were used in each grazing treatment. Infiltration rates were consistently less in the midgrass (bunchgrass) than in the shortgrass (sodgrass) community. The HCG pasture was severely overgrazed and infiltration rates were reduced to about one-half those in the MCG pasture. The midgrasses in this pasture were destroyed after 26 months of overgrazing. Infiltration rates in the SDG pasture, stocked at double the recommended rate, decreased during the study period. Infiltration rates in the SDG pasture shortgrass community, near the end of the study, approached those in the HCG pasture. The greatest infiltration rates for both communities were maintained in the MCG pasture. Infiltration rates for the midgrass community remained relatively stable during the study when the general trend in the SDG and HCG pastures was toward reduced infiltration rates. The nongrazed pasture subsequent to the 1980 drought had a general increase in infiltration rates.
    • Ecophysiological Studies of Eleusine indica (L.) Gaertn. and Sporobolus pyramidalis P. Beauv. at Ibadan, Nigeria

      Sharma, B. M. (Society for Range Management, 1984-05-01)
      Eleusine indica and Sporobolus pyramidalis are common grasses in the tropics, including Ibadan, Nigeria. The former is considered a good fodder when young, but the latter has low grazing quality. The objective of this study was to describe some of the morphological characteristics of these 2 prominent species. S. pyramidalis is a taller grass having more roots per culm and a longer inflorescence. Seeds of the 2 grasses germinated between 20 degrees C and 35 degrees C and emergence declined with increasing depth until it was zero at and 4 cm for E. indica and S. pyramidalis, respectively. S. pyramidalis had a higher rate of germination. The 2 species have stomata on both leaf surfaces, but the number is greater on the adaxial surface. Experiments indicate that E. indica is more tolerant and adaptable to biotic disturbances. The biomass contribution by E. indica and S. pyramidalis is estimated at 1,100 kg/ha 300 kg/ha, respectively.
    • Change in Bacterial Populations Downstream in a Wyoming Mountain Drainage Basin

      Skinner, Q. D.; Adams, J. C.; Beetle, A. A.; Roehrkasse, G. P. (Society for Range Management, 1984-05-01)
      Ten bacteriological tests were utilized to monitor different bacterial populations found in water samples taken from streams draining high mountain rangeland. Livestock grazing and recreation constituted the major uses of the study area. Vegetation types were typical of those found in other sub-alpine and alpine zones in the central Rocky Mountains. Results show differences in counts of bacteria between sampling sites along individual streams sampled with the exception of those organisms capable of reducing nitrate were not significant. A seasonal variation in the numbers of bacteria were found between streams. This variation is not fully explained by drainage basin areas or related to runoff. In contrast, within each stream counts varied with season and could be related to runoff. Bacterial populations which indicate fecal pollution were low and probably derived from animals not man. Wet meadows and bog areas under snow may be possible sources for sulfate reducing bacteria and those organisms capable of reducing nitrate.
    • Cattle Behavior on a South Florida Range

      Tanner, G. W.; Sandoval, L. D.; Martin, F. G. (Society for Range Management, 1984-05-01)
      Grazing, resting, defecating, and urinating behaviors of cattle (Zebu-European cross breeds) were monitored seasonally on a south Florida range from November 1980 through August 1981. Individual animals were continuously during daylight hours in a pasture containing 4 plant communities. Distributions of time spent grazing and resting and counted occurrences of excretion were significantly different among the 4 seasons. Grazing time in the 4 plant communities was not in proportion to their size. Cattle grazed more in those communities that had the best quality of forage available. Cattle grazed more in the freshwater marsh during fall but spent more time in the ecotone during spring and summer. Shade was not a requisite for resting sites, even during the warmest days. Excretion activities were more closely associated with grazing than resting.
    • A Method for Estimating Economic Injury Levels for Control of Rangeland Grasshoppers with Malathion and Carbaryl

      Onsager, J. A. (Society for Range Management, 1984-05-01)
      A theoretical "average" rangeland grasshopper weighs 81.6 mg (dry weight) in the adult stage and consumes 9, 22, and 53 mg of forage/day in the 4th instar, 5th instar, and adult stages, respectively. Criteria for a computer program are presented whereby grazing pressure from grasshopper infestations can be predicted as a function of initial density and normal daily rate of survival. The benefits of a contemplated control measure may then be estimated through appropriate adjustment of the survival rate. By assigning dollar values to the worth of forage and cost of treatment, the lowest infestation that will justify control measures can be determined. The technique is demonstrated for 2 effective but dissimilar insecticides, malathion and carbaryl. By using actual treatment costs for 1981 control programs and by assuming that an AUM (364 kg of forage) saved from destruction by grasshoppers has a marginal value product of $14, it was calculated that grazing by grasshoppers must approach 0.25 AUM/ha before treatment becomes economical. If treatments are not applied before carrying capacity has been depleted by grasshoppers, then the forage that is saved cannot be harvested. Thus, early treatments with both chemicals are much more economical than late treatments.