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Plantspesievoorkeure van vleisbeeste in die Ho"eveldstreek onder 'n stelsel van beheerde selektiewe beweiding

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dc.contributor.advisor Theron GK, Prof en
dc.contributor.advisor Bredenkamp GJ, Prof en
dc.contributor.author De Beer AS en
dc.date.accessioned 2016-09-26T06:26:35Z
dc.date.available 2016-09-26T06:26:35Z
dc.date.submitted 1988 en
dc.identifier.uri http://hdl.handle.net/20.500.11892/173886
dc.description.abstract The purpose of this study was to identify species composition differences between different veld ecotopes as well as to monitor grass species preferences, by cattle, under a system of controlled selective grazing. The study was carried out on the Departmental Experimental Farm of the Highveld region in Potchefstroom, which covers a total area of 3 951 ha. The predominant rock types in the study area are andesite, diabase and quartzite. The experimental farm is situated in land types Fb 13 and Be 25. The soil types consist of a number of soil series with a relatively high clay content, although exceptions do occur. The experimental farm is located in climatic zone H with a mean annual rainfall of 650 mm which falls mainly during the summer months. The area is also characterised by extreme daily and seasonal temperature fluctuations. Eighteen camps, representing six different veld ecotopes of the "Cymbopogon" - "Themeda" Veld Type were investigated. A survey of herbaceous species, using the wheel-point method, was done in each camp at the commencement of the study period. The utilisation of the different grass species was monitored after each grazing period. The chemical analyses of the different grass species included the in vitro digestibility and crude protein determinations. Meteorological data collected included:rainfall, temperature, evapotranspiration and soil moisture. Species composition of the different camps was analysed using Detrended Correspondence Analysis (DCA) and multi-variate regression analysis. For the species utilisation data only the latter analysis was used. Veld ecotopes were identified in the DCA ordination and could be related to differences in soil form, serie and terrain unit. This study indicates that aspect, clay percentage and soil depth are the most important environmental factors influencing species abundance. Since these factors vary on different ecotopes, it follows that species composition will also vary between different ecotopes thus supporting the principle of fencing off veld ecotopes to minimise area selection. The availability of plant material had the greatest influence on utilisation of grass species while clay percentage and the season of utilisation played a minor role. A higher clay percentage of the soil will therefore cause moisture stress in a plant sooner than a lower clay percentage in the same rainfall region. Seasonal variation of utilisation was especially prominent in the case of "Heteropogon contortus". The cumulative contribution of availability expressed as a percentage of the total R<sup>2</sup> (%) illustrates the preference of a specific species, The preference rating of the fourteen most abundant species can be grouped as follows: Group 1 (Low preference) "Elionurus mutlcus" "Heteropogon contortus" "Hyparrhenia hirta" Group 2 (Average preference) "Aristida congesta" "Cymbopogon plurinodis" "Digitaria eriantha" "Eragrostis curvula" "Panicum coloratum" "Setaria sphacelata" "Themeda triandra" Group 3 (High preference) "Cynodon dactylon" "Eragrostis chloromelas" "Eustachys paspaloides" "Sporobolus fimbriatus" Species preference is one of the most important factors for the determination of species desirability. This study supports the principles of controlled selective grazing (CSG) namely, the fencing of veld on the basis of veld ecotopes as well as the grazing of a specific group of grass species. The results could also be used to determine a species desirability index. en
dc.language Afrikaans en
dc.subject Agriculture en
dc.subject Plant production en
dc.title Plantspesievoorkeure van vleisbeeste in die Ho"eveldstreek onder 'n stelsel van beheerde selektiewe beweiding en
dc.type Masters degree en
dc.description.degree MSc(Agric) en


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