Articles by Author: Clw Jones

Search results for Clw Jones

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  1. The Use of Roots to Test N, P and K Deficiencies in <em>Eucalyptus</em> Nutrition

    Item type: Journal Article • Journal: South African Forestry Journal
    Bioassays have been developed which can provide diagnostics of the nutritional status of trees. They measure the flux of N, P or Rb for K into roots from standard solutions where the rate of influx is inversely related to nutrient...
  2. Stimulation of Bud Production in <em>Eucalyptus globulus</em> by Paclobutrazol Application

    Item type: Journal Article • Journal: South African Forestry Journal
    Trunk injection of paclobutrazol (Clipper) significantly increased the bud crop on 7-year-old Eucalyptus globulus (Labill.) seed orchard trees, within one year of application. This is the first reported stimulation of reproduction to occur, with eucalypts, in the season of application...
  3. Outline of a new approach to the study of competition

    Outline of a new approach to the study of competition

    Differential coefficients of five time‐dependent functions are proposed to quantify and define the following: the effect of competition on each of two competing populations, the relative aggressiveness of the populations, the competitive ability of each population with respect to the...
  4. A way to measure the spread of plants from a focus

    A way to measure the spread of plants from a focus

    The relative frequency of occurrence of plants (or plant parts) is determined at increasing distances from a focus, where the relative frequency is unity. The area under the resulting frequency/distance curve is determined, as a measure of spread. Effect of...
  5. Production curves for pastures and veld

    Production curves for pastures and veld

    The Gompertz curve applied to forage cumulative yields can be specified with three or more data points (yields at known times, including a possible zero yield at the start). Good correlations between pasture experimental data and the Gompertz curve, fitted...
  6. Effect of selective defoliation on species in mixed swards

    Effect of selective defoliation on species in mixed swards

    Sown pastures of Paspalum dilatatum (and other species) in Natal are subject to degradation by Eragrostis plana (mshiki) invasion. The ratio between these two grasses, growing together in small plots, was governed primarily by the relative heights, and secondarily by...
  7. A theoretical analysis of foraging efficiency of grazing animals

    A theoretical analysis of foraging efficiency of grazing animals

    A mathematical model of the change in quantity of forage during grazing is constructed, assuming (1) that forage requirement by grazing animals is constant, and (2) that intake is equal to requirement when forage is in free supply but (3)...
  8. Notes on the value of <em>paspalum vaginatum</em> sw. As a pasture grass for saline and structureless soils

    Notes on the value of <em>paspalum vaginatum</em> sw. As a pasture grass for saline and structureless soils

    Paspalum vaginatum Sw. pastures were established on soils which had been denuded and physically degraded by over‐irrigation with an industrial effluent containing a high concentration of Na2SO4. The grass not only colonized the saline areas, but was able to tolerate...
  9. Simulation modelling in agriculture: General considerations

    Simulation modelling in agriculture: General considerations

    A computer simulation model is a detailed working hypothesis about a given system. The computer does all the necessary arithmetic when the hypothesis is invoked to predict the future behaviour of the simulated system under given conditions.