Tiller defoliation of <i>Hilaria mutica</i> (Buckl.) Benth. under seasonal high-density rotation and continuous stocking

TitleTiller defoliation of Hilaria mutica (Buckl.) Benth. under seasonal high-density rotation and continuous stocking
Publication TypeThesis
Year of Publication1989
AuthorsKone D
Number of Pages68
Date Published1989
UniversityNew Mexico State University
CityLas Cruces, New Mexico
Thesis TypeM.S. Thesispp
Call Number00161
Keywordscattle grazing, tiller defoliation, cattle, stocking strategies, dissertation, dissertations, grass, tiller defoliation, Hilaria, tiller defoliation, range management, theses, thesis
AbstractHilaria mutica (Buckl.) Benth. commonly called tobosa, is a warm-season, native perennial grass. Spread of this grass under arid conditions occurs mainly from rhizomes. Tobosa was seasonally grazed with cattle under high-density (4.83 AU/ha) rotation and low-density (0.35 AU/ha) continuous management strategies in 1986 and 1987 to evaluate patterns of utilization. Each year 80 tillers were monitored under each grazing strategy to evaluate frequency and intensity of defoliation. Under high-density rotational grazing, 92% of the tillers were grazed at least once with a mean height reduction of 31% or 53 mm and an average of 2 leaves removed per tiller. Under low-density continuous grazing only 29% of the tillers were grazed at least once. This resulted in a 14% mean reduction in tiller height or 25 mm mean height reduction and one leaf removed per grazing event. There were a similar number of tillers defoliated at least once in 1986 (51%) compared to 1987 (65%), averaged over both treatments within years. These defoliations contributed to a mean height reduction of 41% or 3 leaves/tiller removed in 1986 compared to a height reduction of 12% or 2 leaves/tiller removed in 1987. During the first grazing cycle, 55% of the tillers averaged over grazing strategies and years were grazed more than once. This contributed to a mean plant height reduction of 27% or 49 mm compared to 61% of the tillers being grazed more than once (36% reduction or 53 mm) during the second grazing cycle. The overall correlation coefficient (r = 0.26) indicated height removed did not affect number of leaves removed. Nevertheless, high-density rotation stocking increased frequency and intensity of defoliation. Between grazing cycles in 1987, mean plant height decreased 29 mm under low-density stocking compared to a mean increase in plant height of 68 mm under high-density stocking. The mean number of green leaves decreased by 1 under low-density stocking compared to high-density stocking in which there was a mean increase of 1. The mean number of brown leaves per culm was greater under high-density stocking (1) compared to low-density stocking (