Articles by Author: Erin Johnson Williams

Search results for Erin Johnson Williams

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  1. A vacuum filtration and leaching method for the colorimetric determination of ammonium and nitrate nitrogen in soils

    A vacuum filtration and leaching method for the colorimetric determination of ammonium and nitrate nitrogen in soils

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    The extracting solution and soil were separated by using vacuum filtration, followed by continuous leaching. The procedure was evaluated by spiking five different topsoil samples (having a wide range of physical and chemical properties) with ammonium nitrate and determining the...
  2. Utilization of initially-applied labelled ammonium nitrate by three successive crops

    Utilization of initially-applied labelled ammonium nitrate by three successive crops

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    The aim of the study was to compare N uptake from initially-applied NH4 + and NO3- ions and to compile a balance sheet for applied fertilizer N. In a pot experiment, maize, sorghum and sunflower plants were grown in succession,...
  3. Effects of sodium sulphate, sodium chloride and manganese sulphate on kikuyu (<em>Pennisetum clandestinum)</em> growth and ion uptake

    Effects of sodium sulphate, sodium chloride and manganese sulphate on kikuyu (<em>Pennisetum clandestinum)</em> growth and ion uptake

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    Irrigation with saline water is increasingly practised yet an understanding of plant response to different salt types remains largely elusive. Our study investigated the effects of irrigation with simulated effluent containing three salts on the growth and composition of a...
  4. Effect of timing and concentration of rest breaking agents on budburst in ‘Bing’ sweet cherry under conditions of inadequate winter chilling in South Africa

    Effect of timing and concentration of rest breaking agents on budburst in ‘Bing’ sweet cherry under conditions of inadequate winter chilling in South Africa

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    The effect of timing of various rest breaking agents (RBAs) on vegetative and floral budburst, and production efficiency was investigated on 4-year-old ‘Bing’ sweet cherry trees on ‘Gisela® 5’ rootstock. Two experiments were conducted, near Clarens (28°28’S; 28°19’E, 1860 m.a.s.l)...
  5. SOME RESULTS ON BUDS, STEMS AND FAULT TOLERANCE IN HYPERCUBES OF DIMENSION ⋚ 5

    SOME RESULTS ON BUDS, STEMS AND FAULT TOLERANCE IN HYPERCUBES OF DIMENSION ⋚ 5

    Item type: Journal Article • Journal: Quaestiones Mathematicae
    We determine the minimum number of faulty links in a 5-dimensional hypercube so that no 2-dimensional subcube is fault free. The degree sequences of some related extremal graphs are also determined.