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Microhistological analysis of epidermal fragments in feces is often used to estimate the diet of herbivores but is not generally accepted as a consistently reliable method. Gross errors arise, especially when diets are composed of herbage components with widely different morphological and structural characteristics. The present study investigated the possibility of using such physical characteristics to improve the reliability of the method. Over a 7 day period, 4 rumen-fistulated beef cows were given a fixed diet composed of a shrub, a grass, and a forb component. On the last 2 days, samples of rumen content and feces were taken for analysis of epidermal fragment. Forbs were under-estimated, grasses over-estimated, and shrubs correctly estimated. Correction factors to estimate true diet composition were defined as the biomass represented by the specific epidermal fragments (epidermal weight index) and the degree of degradation to which the epidermis is subjected in the digestion process (epidermal erodibility factor). These factors account for characteristic physical features of the different dietary components and were measured directly or were derived from the calibration experiment. The utility of such factors depends on accurate determination of the component variables and may be overshadowed by sampling error and observer bias in the microhistological identification of epidermal fragments.

During 1981-83, we studied 19 grasses for potential improvement of dry tropical (1,001 mm annual rainfall) rangelands in Hainan Island, China. The productivity and persistence of the grasses were tested on sandy ( 5 plants/m2), but only 6 cultivars produced yields > 1.5 metric tonne (t)/ha. Melinis minutiflora Beauv., Brachiaria decumbens Stapf. and Chloris gayana Kunth. yielded more than 1.5 t/ha in 3-year-old swards on both soils, whereas Panicum maximum Jacq. and Setaria sphacelata (Schum.) Stapf. ex Massey only performed well on fertile loam soil. Grass establishment was superior on sandy soil, but plant density did not correlate well with production which was higher on red loam soil due to better waterholding capacity and nutrient status. Compatibility of these successful grasses with companion legumes was low with legumes contributing 4 t/ha. S. sphacelata was the only grass to form a stable mixture with companion legumes. [Macroptilium atropurpurem (D.C.) Urban and Stylosanthes guianensis (Aubl.) Sw.], which yielded more than 1.1 t/ha in 3-year-old swards on loam soil. This combination was recommended for improvement of loam soil rangelands. It is concluded from this study that range improvement with perennial grasses is confined to fertile soils, while direct broadcast of Stylosanthes legumes only into grazed native pastures is the practice recommended for improvement of infertile sandy soil until persistent low P tolerant grasses are found for the dry tropics.

Crude protein content of herbage produced by buffelgrass, blue panicgrass, and Bell rhodesgrass was improved with nitrogen and phosphorus fertilization and clipping every 4 orJ 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 bluestenm herbage was only slightly increased with the highest level of fertilization, regardless of clipping frequency. The South Texas Plains occupies nearly 9 million hectares of level to rolling terrain with elevations ranging from sea level to 95 m. Annual rainfall ranges from 45 to 75 cm with peaks occurring in May and September. Because of the long growing season and rainfall patterns, this area has a high potential for forage production. However, primarily as a result of continued excessive grazing of domestic livestock and cessation of fires, undesirable woody species have increase to the detriment of naturally occurring desirable vegetation (Scifres 1980). Brush management as a part of overall sound range management has proven its merit in restoring forage production (Scifres et al. 1976, 1980; Polk et al. 1976). Generally, natural revegetation through secondary succession is too slow for economical returns following high-cost mechanical control of undesirable woody species. Artificial revegetation with commercially available, adapted species is often considered the most feasible alternative for rapid restoration of these grazing lands. Major species that have been seeded successfully include buffelgrass (Cenchrus ciliaris), Bell rhodesgrass (Chloris gayana), Kleberg bluestem (Dicanthium annulatum), and blue panicgrass (Panicum antidotale). Although these grasses have been utilized in the overall range improvement program in south Texas for the past 4 decades, little is known about specific post-seeding management practices which could improve forage yield and quality. Brief descriptions, planting dates, seeding rates, and responses to irrigation and fertilization are found in experiment station leaflets (Novosad and Pratt n.d., Lancaster n.d., Lancaster 1949, and Anon. 1968). Since most of the livestock in this area are raised in yearlong cow-calf operations, high protein forage is required throughout the year to meet demands of growing calves and lactating cows. Waite At the time of this research, authors were graduate research assistant and associate professor, College of Agriculture,Texas Al and April 15 and 582 JOURNAL OF RANGE MANAGEMENT 36(5), September 1983 This content downloaded from 157.55.39.127 on Mon, 27 Jun 2016 05:36:06 UTC All use subject to http://about.jstor.org/terms Table 1. Fertility levels and pH of the soil of the study area where clipping frequency and fertilization was evaluated relatived to crude protein constants and herbage production of 4 grass species near Kingsville, Texas, during 1972-1973.' Nutrient availability

The influence of water stress on growth of four grasses was investigated. Panicum coloratum and Chloris gayana, the two C 4 species, were more adversely affected, while the two C 3 species (Poa pratensis and Lolium perenne) were found to tolerate the water stress conditions better as reflected by a comparatively smaller decline in their biomass.

SUMMARY (1) To describe the regulation of genet density of Rhodesgrass (Chloris gayana Kunth.) and variations in this process, seven cultivars were sown at four densities and the changes of genet densities were recorded during the year of sowing. (2) Genet density generally decreased nearly exponentially with half lives of 0 8-1 8 months. (3) During the sward establishment phase, genet mortality was positively correlated with the surviving genet density. The 8 0-fold range of sowing density converged into a 2 5fold range of genet density at 58 days after sowing. (4) Significant differences in mortality among cultivars were observed after the sward established. Genet mortality did not then correlate with the surviving genet density. (5) While there were appreciable variations in surviving genet density and genet weight, attributable to both sowing density and cultivars at the end of the year, there was nearly complete compensation between the two traits in both sources of variation, which regulated the stand yield of Rhodesgrass sward to within a narrow range.

(1) In grasslands in Uganda dominated by Hyparrheniafilipendula and Themeda triandra, biomass of shoots increases to about 0-5-0 7 kg m2 in the rainy season without grazing, and to about half this value with grazing. Maximum leaf-area index in ungrazed grassland generally does not exceed 3-0. Biomass of roots varies seasonally from 0 5 to 2 0 kg m2 (2) In this grassland, and in grassland dominated by Sporobolus pyramidalis and Chloris gayana, the quantities of dry matter which can be harvested by successive monthly cuts at 5 or 20 cm above the ground vary from almost nothing in dry seasons to the equivalent of 4 or 2 g m2 per day dry matter production respectively in rainy seasons. (3) These values are for grassland not grazed by large animals; with grazing the rates are approximately halved, and the differences provide estimates of the rates of natural grazing. (4) The mean values for the rate of grazing throughout the year are of the same order of magnitude as values calculated from estimates of the energy requirements of the biomass of large mammals on the sites. (5) Monthly production of dry matter and protein are significantly correlated with rainfall, giving regression constants of 6 8 g m2 dry matter and 0 56 g m2 protein per month per cm of rain.

Many of the reseeded pastures of the better known grasses when planted at Frankenwald Field Research Station have proved unsuitable. This lack of success was in certain cases due to poor germination and establishment, e.g. Panicum coloratum. In other cases, e.g. Chloris gayana, good stands were established in the first year, but these deteriorated rapidly in succeeding years, being soon replaced by other volunteer grasses, chiefly Eragrostis curvula,* E. plana, Cynodon dactylon, Sporoboluspyramidalis and Hyparrhenica hirta. Eragrostis occurs in the second grass stage of secondary succession as is found on the sandy soils of the Transvaal Highveld, being later replaced by Hyparrhenia hirta (RoseInnes 1939). The increase of Eragrostis in veld where heavy applications of nitrogenous fertilizer have been applied has clearly been shown by Meredith (1947). Further, the effect of fertilizer in maintaining succession at the Eragrostis stage has been demonstrated by Davidson (1955) and Leigh (1958). It is desirable to maintain a pure stand of the selected variety of grass planted. Volunteer grasses, besides often lowering production per area, frequently give rise to difficulties associated with management. With this in view, the following experiment was carried out to determine whether certain types of E. curvula were more persistent and less susceptible to invasion by Hyparrhenia hirta and dicotyledonous weeds than other types. Certain varieties of Eragrostis curvula, which is a perennial bunch grass, are widely used as ley grasses in certain areas of South Africa. PROCEDURE The experiment was carried out at Frankenwald Field Research Station which is situated on latitude 260 41' S. and long. 280 06' E. at 4950 ft (1509 m) above sea level. The soils, derived from pre-Witwatersrand old granites, are acid, sandy, laterized and shallow. The annual rainfall is 30 in. (76 cm). The experimental layout consisted of a randomized block with three replicates. In each block there were twenty varieties of E. curvula and one variety each of E. plana, Digitaria smutsii and Chloris gayana. The experiment was planted in broadcast stands in February 1956. After a careful study of the varieties known collectively under the name of Eragrostis curvula, it was found possible to group the varieties under five main types to which the names 'Curvula', 'Chloromelas', 'Robusta blue', 'Robusta intermediate' and 'Robusta green' were assigned. This classification was based primarily on such morphological characters as leaf colour, leaf structure, inflorescence size and general growth habit. It was, however, realized that such characters are influenced by growth and fertilizer treatment. Nevertheless the results of further studies of such characters as anatomy