Articles by Author: Roelof Burger

Search results for Roelof Burger

We found 46 results for you
  1. Bird species richness and densities in relation to sulphur dioxide gradients and environmental variables

    Bird species richness and densities in relation to sulphur dioxide gradients and environmental variables

    Item type: Journal Article • Journal: Ostrich: Journal of African Ornithology
    The expansion of coal-fired power stations in South Africa has resulted in growing environmental concerns as they are the largest emitters of sulphur dioxide (SO2). Sulphur dioxide emissions from power plants pose a potential threat to avian populations. However, the...
  2. Die reaksie van <em>anthephora pubescens</em> nees op verskillende intensiteite en frekwensies van ontblaring<sup>(1)</sup>

    Die reaksie van <em>anthephora pubescens</em> nees op verskillende intensiteite en frekwensies van ontblaring<sup>(1)</sup>

    ‘n Faktoriaal experiment met vier frekwensies (2, 4, 6 en 8 weekliks) en vyf intensiteite (2, 5, 8, 11 ot 14 cm hoogte) van sny is in potproewe op Anthephora pubescens uitgevoer. Die totale DM‐snyopbrengs, wortelproduksie en bogroei/wortelverhouding is bepaal.
  3. Vergelyking van ammoniumsulfaat, kalksteenammo- niumnitraat en ureum onder besproeiingstoestande op twee gronde van die Vaalhartsbesproeiingskema

    Vergelyking van ammoniumsulfaat, kalksteenammo- niumnitraat en ureum onder besproeiingstoestande op twee gronde van die Vaalhartsbesproeiingskema

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    Op 'n sandgrond met 9% klei in die B21-horison het ammoniumsulfaat hoër koringopbrengste gelewer as kalksteenammoniumnitraat en ureum. 'n Sandleemgrond met 20% klei in die B21-horison, het geen verskille tussen stikstofbronne getoon nie. Logingstudies in grondkolomme het aangetoon dat feitlik...
  4. A proposed mechanism for the volatilization of ammonia from fertilized neutral to alkaline soils

    A proposed mechanism for the volatilization of ammonia from fertilized neutral to alkaline soils

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    Ammonia volatilization from five soils, ranging in clay content from 7,6 to 49,9%, were determined after pH values of the soils were adjusted to 8,0. Ammonium sulphate, limestone ammonium nitrate, urea, monoammonium phosphate and diammonium phosphate were applied on the...
  5. Anorganiese stikstof in mieliegronde van die Oranje-Vrystaat en Transvaal met planttyd, 1984

    Anorganiese stikstof in mieliegronde van die Oranje-Vrystaat en Transvaal met planttyd, 1984

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    Ondersoek is ingestel na die hoeveelheid anorganiese stikstof wat met planttyd gedurende die 1984/85-seisoen in mieliegronde van die Oranje-Vrystaat en Transvaal teenwoordig was. By 82 lokaliteite, wat verspreid oor hierdie gebied voorkom, is grondmonsters ingesamel. Grondmonsters is op 300 mm...
  6. Laboratory measurements of ammonia volatilization from five nitrogen-containing fertilizers after surface application at different rates on a neutral to alkaline soil

    Laboratory measurements of ammonia volatilization from five nitrogen-containing fertilizers after surface application at different rates on a neutral to alkaline soil

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    Volatilization losses of NH3 from five fertilizers, namely (NH4)2SO4, LAN, urea, MAP and DAP were determined. The fertilizers were applied to a Bainsvlei soil of which the pH was adjusted to 6,5; 7,6; 8,3 and 9,1. The application levels were...
  7. Die swawelstatus van besproeiingsgronde onder veranderende bemestingspraktyke

    Die swawelstatus van besproeiingsgronde onder veranderende bemestingspraktyke

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    Die effek van die gebruik van swawelvrye teenoor swawelbevattende bemestingstowwe op die swawelstatus van 'n Mangano-grond van Vaalharts, is met behulp van 'n potproef ondersoek. Waar swawelvrye bemestingstowwe gebruik is was gebreksimptome na die derde snysel reeds duidelik sigbaar by...
  8. Effect of application methods on ammonia volatilization from soils in a controlled environment

    Effect of application methods on ammonia volatilization from soils in a controlled environment

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    The objective of this investigation was to compare different application methods whereby ammonia losses from nitrogen fertilizers can be limited when applied to alkaline soils. Three application methods were simulated, namely broadcasting, ploughing under and band placement. Five nitrogen fertilizers,...
  9. Penetration resistance of fine sandy apedal soils as affected by relative bulk density, water content and texture

    Penetration resistance of fine sandy apedal soils as affected by relative bulk density, water content and texture

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    The major physical properties that control the penetration resistance of soils are the degree of soil compaction, water content and particle size distribution. Sandy soils with well-sorted particle size distributions and low cohesivity compact and consolidate easily under pressure. Six...
  10. Movement of ammonia plus ammonium from nitrogen fertilizers band placed in alkaline soils

    Movement of ammonia plus ammonium from nitrogen fertilizers band placed in alkaline soils

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    Movement of NH3 plus NH4 + from nitrogen fertilizers, band placed either as crystals or as granules in alkaline soils, was determined. The pH values of these soils, whereof the clay contents ranged from 7,6 to 49,9%, were adjusted to...