Articles by Keyword: Modelling

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  1. Die wiskundige simulering van koolhidraattranslokasie in natuurlike grasveld<sup>1</sup>

    Item type: Journal Article • Journal: Journal of the Grassland Society of Southern Africa
    Die groeifunksies benodig vir die simulasie van produksie van ‘n Themeda triandra‐grasveld met behulp van die PUTU 11 simulasiemodel is ontwikkel. Vir die ontwikkeling van die model is die veldproduksiedata van die 1980/81 groeiseisoen gebruik waarna dit suksesvol, vir drie...
  2. Development of a technique for assessing veld condition in the Kruger National Park using key grass species

    Item type: Journal Article • Journal: Journal of the Grassland Society of Southern Africa
    A technique based on key grass species was developed for assessing veld condition in the Kruger National Park in terms of its potential to produce grass forage for consumption by herbivores and fine fuels for veld burning. Fourteen grass species...
  3. The regrowth of <em>Colophospermum mopane</em> following clearing

    Item type: Journal Article • Journal: Journal of the Grassland Society of Southern Africa
    The recovery of cleared Colophospermum mopane thicket in the eastern Transvaal lowveld, to a level where its effect on grass production is similar to that in the pre‐cleared state, occurs within fourteen years. Based on certain assumptions, the ‘effective duration’...
  4. Remote sensing applications for monitoring rangeland vegetation

    Item type: Journal Article • Journal: Journal of the Grassland Society of Southern Africa
    Remote sensing techniques hold considerable promise for the inventory and monitoring of natural resources on range‐lands. A significant lack of information concerning basic spectral characteristics of range vegetation and soils has resulted in a lack of rangeland applications. To use...
  5. An attempt at estimating solar radiation at South African sites which measure air temperature only

    An attempt at estimating solar radiation at South African sites which measure air temperature only

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    Daily potential surface radiation values were calculated for selected South African weather stations. These were used, together with various air temperature parameters, to derive regression equations to estimate actual surface solar radiation at sites lacking the required instrumentation. A single...
  6. Thermal time bias in maize growth simulation due to mesoscale weather effects

    Thermal time bias in maize growth simulation due to mesoscale weather effects

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    The effect of cold air advection on the estimates of daily thermal time with a base temperature of 8°C (DTT8), calculated using maximum and minimum screen temperatures (max./min. values), was examined. Screen temperature data for at least three maize-growing seasons...
  7. Evaluering en kalibrering van CERES-Maize. 1. Nie-lineêre regressie om genetiese parameters te bepaal

    Evaluering en kalibrering van CERES-Maize. 1. Nie-lineêre regressie om genetiese parameters te bepaal

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    Die genetiese parameters van die meeste plaaslike mielie cultivars wat as inset van CERES-Maize benodig word, is nog nie bepaal nie. Sodanige parameters kan met behulp van bestaande oesdata en fenologiese datums, uit veldproewe afgelei word. Programmatuur kan gebruik word...
  8. Simple regression models for the qualitative prediction of atrazine and terbuthylazine leaching

    Simple regression models for the qualitative prediction of atrazine and terbuthylazine leaching

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    Leaching of atrazine [6-chloro-N-ethyf-N′-(methylethyl)-1,3,5-triazine-2,4-dlamine] and terbuthylazine [6-chloro- N-(1,1-dirnelhylethyt)-N′-ethyl-1,3,5-triazlne-2,4-diamine] was studied in 23 soils by means of the soil thick-layer leaching method. The equivalent of 4 kg ai ha−1 of both herbicides was leached with water equivalent to 129 mm rain...
  9. Calibration of CERES3 (Maize) to improve silking date prediction values for South Africa

    Calibration of CERES3 (Maize) to improve silking date prediction values for South Africa

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    Silking which coincides with the mid-summer drought in South Africa, could have a significant negative effect on maize yield. Errors in the prediction of silking date could contribute to errors in kernel number simulation, and consequently to errors in yield...
  10. Calibration and validation of the SWB model for sunflower (<em>Helianthus annuus</em> L.)

    Calibration and validation of the SWB model for sunflower (<em>Helianthus annuus</em> L.)

    Item type: Journal Article • Journal: South African Journal of Plant and Soil
    The Soil Water Balance (SWB) generic crop growth and irrigation scheduling model was used to simulate the crop growth and soil water balance of sunflower (Helianthus annuus L. c v. CAR 1199 and SO 306) grown at Rietrivier. The objectives...