• Clipping Frequency and Fertilization Influence Herbage Yields and Crude Protein Content of 4 Grasses in South Texas

      Mutz, J. L.; Drawe, D. L. (Society for Range Management, 1983-09-01)
      Crude protein content of herbage produced by buffelgrass, blue panicgrass, and Bell rhodesgrass was improved with nitrogen and phosphorus fertilization and clipping every 4 or 8 weeks, compared to harvests only at the end of the growing season. Within a fertilization level, the 8-week clipping frequency generally increased dry matter production of the grasses over the 4-week clipping frequency or the end-of-season single harvest. Kleberg bluestem herbage generally contained less protein at all phenological stages than that of buffelgrass, blue panicgrass, or Bell rhodesgrass, and dry matter production was not increased by fertilization. Crude protein content of Kleberg bluestem herbage was only slightly increased with the highest level of fertilization, regardless of clipping frequency.
    • Correlation of Honey Mesquite Response to Herbicides with Three Plant Variables and Soil Water

      Meyer, R. E.; Hanson, J. D.; Dye, A. J. (Society for Range Management, 1983-09-01)
      Honey mesquite [Prosopis juliflora (Swartz) DC. var. glandulosa (Torr.) Cockerell] response to sprays of 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid) and picloram (4-amino-3,5,6-trichloropicolinic-acid) + 2,4,5-T was evaluated and correlated with maximum daily photosynthetic rate, upward movement of methylene dye, xylem pressure potential, and percent soil water. Picloram + 2,4,5-T was superior to 2,4,5-T alone for killing honey mesquite from May 15 through August 4. Time of day the herbicide was applied had no significant effect on control. Maximum daily photosynthetic rate varied from 32.9 to 10.1 mg ${\rm CO}_{2}\ {\rm dm}^{-2}$ leaf area hr-1 and was highly correlated (r = 0.89 to 0.92) with honey mesquite control with herbicides. Rate of upward movement of methylene blue dye in the xylom varied from 295 to 44 cm hr-1. (MPa) while soil water content varied from 11.5 to 18.6%. Upward movement of methylene blue dye, xylem pressure potential and percent soil water were not significantly correlated with honey mesquite control.
    • Herbage Dynamics and Forage Quality of Texas Cupgrass (Eriochloa sericea)

      Shaw, R. B.; Smeins, F. E. (Society for Range Management, 1983-09-01)
      Herbage dynamics and forage quality of Texas cupgrass (Eriochloa sericea) were monitored during the 1977 and 1978 growing seasons on the Edwards Plateau, Texas. This species was dominant on a shallow rocky range site which had been excluded from grazing for 30 years. Average herbage production was low (527 kg/ha), and mulch constituted 85% of the total biomass. Peak live standing crop was only 145 kg/ha during the study. Green herbage production reflected the ability of this taxon to adjust phenological stage in response to precipitation. Litterbag studies showed decomposition rates of herbage held flat on the soil surface to be twice as rapid as herbage held upright in clumps of Texas cupgrass. This difference in decomposition illustrated the necessity for herbage removal to prevent dead centers and degradation of the stand. Crude protein content of live material averaged 9.8 and 10.7% during 1977 and 1978, respectively. Digestible energy of live herbage averaged 2300 kcal/kg and never went below 2,100 kcal/kg during the study. Forage quality parameters also reflected phenological stage of development.
    • Low-energy Grubbing with Special Blade to Control Algerita

      Cross, B. T.; Wiedemann, H. T. (Society for Range Management, 1983-09-01)
      Algerita (Berberis trifoliolata Moric) infestations on low stony hill range sites in the Edwards Plateau vegetational area of Texas are a problem following primary brush control. Infestations appear well suited to control by low-energy grubbing. A feasibility study indicated the method was economical but plant kill was erratic. Sprouting of lateral roots near the periphery of the grubbed hole accounted for 56% of the regrowth while 13% was attributed to crown tissue attached to taproots. No sprouts originated directly from taproots. Remaining regrowth resulted from problems with blade penetration in the soil. To prevent sprouting, severing the taproot below the crown and uprooting of all lateral roots under the entire plant canopy to a depth of 10 to 15 cm was necessary. Grubber blade modification included an increase in width to 180 cm and an addition of small fins welded on top of the blade to increase plant uprooting. Grubbing with the modified blade resulted in a plant kill of 93% +/- 3.5 (x +/- S.D.) when tested in an algerita infestation of 42 to 195 plants/ha ranging in height from 1.0 to 1.5 m. The grubber averaged 2.13 ha/hr in a 110 plants/ha infestation and cost of $16.43/ha. The ha/hr grubbing rate (Y) plotted against trees/ha densities (X) followed the prediction equation log Y = 1.93 - 0.83 log X with a significant (P<0.01) correlation coefficient of r = 0.91. Low-energy grubbing using the modified grubbing blade is an effective and economical method of controlling algerita.
    • Seasonal Effects of Nitrogen Fertilization on Three Species of South Texas Browse Plants

      Everitt, J. H.; Gausman, H. W. (Society for Range Management, 1983-09-01)
      We conducted a study in Kenedy County of south Texas to determine nitrogen (N) fertilization effects on crude protein (CP), P, Ca, K, and Mg contents of 3 important deer browse plants (granjeno, Celtis pallida; lime pricklyash, Zanthoxylum fagara; and bluewood, Condalia hookeri). Four N fertilizer rates (56, 112, 168, and 224 kg N/ha) were applied in February 1980 to improved rangeland plots where brush was reinfesting. Control plots were nonfertilized. Vegetation samples were assayed for CP, P, Ca, K, and Mg contents on 5 dates: June, September, and December 1980, and April and July 1981. The CP content of plants fertilized with 112 kg N/ha or more was significantly higher (P = 0.05) than those fertilized with 56 kg N/ha or nonfertilized. Except for lime pricklyash plants fertilized with 224 kg N/ha, the CP content of plants fertilized with 168 and 224 kg N/ha was not significantly different from those fertilized with 112 kg N/ha. The addition of 56 kg N/ha had no effect on the species' CP content. Nitrogen fertilization had little effect on the P, Ca, K, and Mg contents of the species. The 3 species from both nontreated and treated plots had adequate CP, Ca, K, and Mg levels for deer nutritive requirements throughout the study, but P levels were generally deficient except in April 1981.
    • Yaupon and Associated Vegetation Response to Seasonal Tebuthiuron Applications

      Duncan, K. W.; Scifres, C. J. (Society for Range Management, 1983-09-01)
      Broadcast applications of tebuthiuron pellets (20% active ingredient [a.i.]) at 2 kg/ha (a.i.) in spring more effectively controlled yaupon than applications in summer, fall or winter on the Post Oak Savannah. Tebuthiuron applications in spring reduced the live canopy of yaupon by 80%. Tebuthiuron at 1 kg/ha did not effectively control yaupon, regardless of season of treatment. Herbaceous response to tebuthiuron was relatively slow because of lack of a seed source in the heavy yaupon covers. However, by December 1980 after applications of tebuthiuron at 2 or 4 kg/ha in spring or summer 1978, grass standing crops were significantly increased. Forb standing crops were highly variable, but there was no apparent forb reduction in 1980 of 1981 where herbicide was applied in 1978-1979.