• Grazing influences on watering point vegetation in the Chihuahuan desert

      Fusco, M.; Holechek, J.; Tembo, A.; Daniel, A.; Cardenas, M. (Society for Range Management, 1995-01-01)
      Long-term influences of livestock grazing on vegetation around watering points was studied on 2 upland Chihuahuan desert ranges in southcentral New Mexico using regression analysis. One range had been conservatives stocked since the 1950's while the other was more heavily stocked. About 45% of the climax vegetation occurred on the heavily stocked range compared to 70% on the conservatively stocked range. During 3 years of study, both ranges were stocked conservatively so annual utilization of the key forage grasses was 30-35%. Regression analyses showed black grama (Boueteloua eriopoda Torr.), mesa dropseed (Sporobolus flexuosus Thurb, Rybd.), threeawn (Aristida sp.), and total perennial grass standing crop increased as distance from water increased on the good condition range (P < 0.05). However, black grama and threeawn standing crop showed no association with distance from water on the fair condition range. Broom snakeweed (Xanthocephalum sarothrae Pursh.), the primary poisonous plant found on both ranges, was associated (r2 = 0.35) with distance from water only on the good condition range in April. Poisonous plants other than broom snakeweed decreased as distance from water increased with the exception of the fair condition range in October. No livestock losses from poisonous plants were noted on either range over the 3 years. We attribute this to the present conservative stocking rates. Our study supports the recommendation that downward stocking rate adjustments be made for the zone more than 1,600 m from water.
    • Response of a mixed native warm-season grass planting to nitrogen fertilization

      Berg, W. A. (Society for Range Management, 1995-01-01)
      Plant available nitrogen limits production of native warm-season grasses on marginal farmland in the Southern Plains. In this western Oklahoma study, N was applied at 0, 35, 70, or 105 kg N ha-1 yr-1 to a mixed stand of blue grama (Bouteloua gracilis (H.B.K.) Lag. ex Griffiths), sideoats grama (B. curtipendula (Michx.) Torr.), little bluestem (Schizachyrium scoparium (Michx.) Nash), sand bluestem (Andropogon hallii Hack.), switchgrass (Panicum virgatum L.) and indian grass (Sorghastrum nutans (L.) Nash). The grass was established on sandy loam soil farmed an estimated 90 years. With near-normal precipitation the first year, production of perennial grasses increased linearly with 26 kg herbage produced kg-1 N applied. In drouth conditions, the second and third years, production averaged 10 kg herbage kg-1 N applied. The fourth and fifth year the stand was not fertilized and residual effects measured. Herbage production increased 10 kg for each kg N applied over the previous 3 years. Blue Grama made up much of this increased herbage production along with warm-season annuals (Panicum capillare L. and Amaranthus retroflexus L.). With increasing N rates the residual N effect increased the proportion of blue grama and decreased the proportion of taller perennial grasses. Thus, N fertilization of mixed native warm-season grass stands established on marginal farmland, typical of stands established on sandier soils under the USDA Conservation Reserve Program, can result in substantial herbage yield increases, however, some of the increased yield may be from weedy species.