• New Mexico Blue Grama Rangeland Response to Dairy Manure Application

      Stavast, Lanson J.; Baker, Terrell T.; Ulery, April L.; Flynn, Robert P.; Wood, M. Karl; Cram, Douglas S. (Society for Range Management, 2005-07-01)
      New Mexico supports over 290 000 dairy cattle. These cattle produce large quantities of manure. It has been suggested excess dairy manure could be applied to rangelands as an organic fertilizer to increase soil fertility and herbaceous production. Manure was applied June 2000 to a rangeland in New Mexico dominated by blue grama (Bouteloua gracilis (Willd. ex Kunth) Lag. ex Griffiths) according to phosphorus (P) content: a recommended (light) rate (54 kg P ha-1) to enhance blue grama growth and a gross overapplication (heavy) rate (493 kg P ha-1) to determine their effects on vegetation. The actual application rate of manure on a dry weight basis was 0, 11 739, and 107 174 kg ha-1. Four replications of control, light, and heavy rates were established. Herbaceous standing crop (kg ha-1) was similar 1 growing season after manure application, and greater 2 and 3 growing seasons after application on the light treatment compared with the control. Initially the heavy treatment suppressed herbaceous standing crop; thereafter, standing crop responded in a linear fashion to rainfall. Three growing seasons after manure application, basal cover was similar between light and control treatments, whereas the heavy treatment continued to be characterized principally by manure/litter cover. Heavy disposal-oriented treatments are not suitable for blue grama rangelands because of persistent declines in herbaceous cover and changes in soil salinity. A light manure application rate that is based on P content can increase forb and in particular grass standing crop on arid blue grama rangelands. Successful rangeland manure applications will depend on proper management to insure objectives are met while minimizing any hazards to the environment.  
    • One-Seed Juniper Sapling Use by Goats in Relation to Stocking Density and Mixed Grazing With Sheep

      Utsumi, Santiago A.; Cibils, Andres F.; Estell, Richard E.; Baker, Terrell T.; Walker, John W. (Society for Range Management, 2010-05-01)
      Suppression of one-seed juniper (Juniper monosperma [Englem.] Sarg.) reinvasion with goats requires achieving levels of defoliation of newly established saplings that eventually kill or suppress plant growth. We tested the effects of stocking density and mixed grazing with sheep on the level of use of one-seed juniper saplings by goats. In summer and spring, groups of 10 does (goats alone, GA) or 5 does and 4 ewes (mixed grazing, MG), grazed 20 X 30 m cells infested with saplings (500-533 ha-1; mean: 0.8 m tall), either continuously for 6 d (low stocking density, LD) or with daily rotation through 10 X 10 m cells during the 6-d period (high stocking density, HD) in a block design. Feeding activity; juniper in feces; utilization of herbaceous vegetation; frequency of saplings with light, moderate, and heavy foliage and bark use; and branch utilization were determined. Goats in HD spent more time feeding on saplings, less time feeding on herbaceous forages, and tended to consume more juniper than goats in LD. Utilization of herbaceous vegetation ranged from 52% to 73% and was higher for MG than GA and for LD than HD. The MG-HD treatment resulted in the highest frequency of short saplings (< 0.5 m) with heavy defoliation in summer and spring, and lowest frequency of saplings with light debarking in spring. Heavy defoliation was more frequent in short saplings, whereas heavy debarking was more frequent in tall (> 1 m) saplings. Sapling mortality was not affected by treatments (P > 0.05) and averaged 5% across treatments. Branch debarking was greater in spring (P = 0.02) and explained approximately 80% of branch mortality and 62% and 52% of the reduction in sapling live crown height and volume. Branch utilization (percent length) was not affected by grazing treatments (range: 45-48%), but was influenced by the length and diameter of branches. This study suggests that high stocking density and mixed grazing stimulate feeding behaviors that increase utilization of juniper saplings by goats. Susceptibility of saplings to defoliation and debarking varies with sapling size, branch structure, and season. Targeted grazing in spring appears to have a greater impact on sapling suppression and branch mortality due to higher debarking frequency. 
    • Riparian vegetation response to different intensities and seasons of grazing

      Lucas, Richard W.; Baker, Terrell T.; Wood, M. Karl; Allison, Christopher D.; Vanleeuwen, Dawn M. (Society for Range Management, 2004-09-01)
      Sustainable management of riparian ecosystems depends on our understanding of these complex systems. Thus far, the scientific literature has not adequately addressed the effects of livestock grazing on riparian areas in the American southwest. Most available information is observational, anecdotal, based on unreplicated experiments, or compares heavily grazed areas to areas from which livestock have been completely excluded. This study, in the Black Range of western New Mexico, compared effects of different seasons of use (cool season, warm season, and dormant season) and grazing intensities (light, moderate, and none) of cattle on young narrowleaf cottonwood (Populus angustifolia James) populations, and herbaceous vegetation in 2 adjacent southwestern riparian areas. Cottonwoods in lightly grazed and moderately grazed plots received significantly greater use than cottonwoods in ungrazed plots which experienced negligible grazing pressure. Increased grazing pressure did not have significant impacts on cottonwood populations. Effects of season of use were significant on both herbaceous species richness and diversity. We conclude that no single riparian area management approach is best in all situations, but the grazing treatments used in this study appear to have been successful at maintaining riparian communities.