| Behaviour of sesquioxic clay soils subjected to alkaline and saline effluents | Thompson, J. G. | 1985 |
KeywordsAlkaline and saline effluents, chloride movement, sesquioxic clay soils, sodicity AbstractThe effects of disposal of alkaline and saline effluents on sesquioxic red clay soils have been monitored for many years on a site in the eastern Transvaal. Recently a high chloride content effluent with a sodium adsorption ratio (SAR) of about 8 has also been experimentally irrigated on a 1-ha block within the disposal area to determine rate of chloride movement in the soil. Under the conditions that prevailed the downward movement of the chloride front was about 1 m per year. In spite of high exchangeable sodium percentage (ESP) values attained in the lower subsoils, the effect on soil permeability has been minimal. Furthermore, soil pH values are low in relation to the sodicity of the lower subsoils. S. Afr. J. Plant Soil 1985, 2: 221–224 AuthorsThompson, J. G. Year Published1985 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1985.10634174 This article contributed by:
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| Invloed van bewerking en besproeiing op die verwering van gneis in die Augrabies-gebied | Eloff, J. F. | 1985 |
KeywordsGneiss, irrigation, properties, soil formation, weathering AbstractFisiese, chemiese en mineralogiese kriteria is gebruik om te bepaal of veranderinge in eienskappe van gronde op gneise, in die Augrabies-gebied, as gevolg van bewerking en besproeiing plaasgevind het. Bewerking en besproeiing van die halfverweerde gneise het die verweringsproses versnel. Dit word deur die volgende verskille bevestig: (i) In A-horisonte van bewerkte gronde het 'n toename in klei-inhoud en KUK-waardes plaasgevind; (ii) sand- en slikfraksies van die meeste bewerkte en onbewerkte gronde bestaan hoofsaaklik uit kwarts, veldspaat (veral albiet) en hoornblende terwyl klein hoeveelhede vermikuliet en mika in die slikfraksie voorkom. Kleifraksies van onbewerkte gronde bestaan hoofsaaklik uit smektiet, mika en kwarts. Kaollniet is veral prominent in A-horisonte wat langer as 10 jaar besproei Is. Vermikuliet het in R- en C-horisonte van enkele van die bewerkte profiele baie sterk pieke getoon. A-horisonte van bewerkte gronde het 'n toename in uit- ruilbare kalium en persentasle koolstof in vergelyking met onbewerkte gronde getoon. Eersgenoemde is waarskynlik die gevolg van verwering en/of bemestlng terwyl laasgenoemde aan 'n hoër plantreste-inhoud as gevolg van bewerkingspraktyke toegeskryf kan word. S.-Afr. Tydskr. Plant Grond 1985, 2: 225–230 AuthorsEloff, J. F., Kirsten, W.
F.A. and Plath, B. L. Year Published1985 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1985.10634175 This article contributed by:
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| Causes, adverse effects and control of soil compaction | Bennie, A.
T.P. | 1985 |
KeywordsCompaction control, controlled wheel traffic, root growth, soil compaction, soil strength AbstractThe causes, adverse effects and control of soil compaction, with special reference to Southern African conditions, are reviewed. The main causes for soil compaction are the well-rounded and -sorted fine sand fraction of the aeolian sandy soils combined with compression by soil tillage equipment. Layers with high penetration resistance decrease rooting depth and density which lead to a reduction in plant nutrient uptake, water uptake and water-use efficiency. A system of deep tillage combined with controlled wheel traffic to predetermined lanes is recommended as a measure of control. S. Air. J. Plant Soil 1985, 2:109–114 AuthorsBennie, A.
T.P. and Krynauw, G. N. Year Published1985 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1985.10634148 This article contributed by:
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| Genotypic tolerance of selected dry bean (Phaseolus vulgaris L.) cultivar s to soluble Al and to acid, low P soil conditions | Noble, A. D. | 1985 |
KeywordsLiming, nutrient solution screening, Phaseolus vulgaris L., phosphorus, tolerance to aluminium AbstractTwelve dry bean cultivare were grown for seven days on filter paper soaked with nutrient solution containing a range of up to 10 mmol Al dm−3. Differential response to Al toxicity, measured as taproot elongation, occurred at Al concentrations of ≧ 2 mmol dm−3. Fifteen cultivare (including four cultivare classified in terms of Al tolerance by the nutrient-solution method) were grown in pots containing an acid (64% acid saturation of CEC), P-deficient clay loam subsoil (Plinthic Paleudult), differentially treated with Ca(OH)2 and CaHPO4. 2H2O. After 35 days the plants were classified in terms of tolerance to acid, low P soil conditions, on the basis of relative topgrowth yields. Three of four cultivare screened by both methods were classified identically: lapar-Rai-54 and W126 as tolerant, and BAT331 as sensitive. S. Afr. J. Plant Soil 1985, 2: 115–119 AuthorsNoble, A. D., Lea, J. D. and Fey, M. V. Year Published1985 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1985.10634149 This article contributed by:
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| Voorspelling van die aanpassingsvermoë van koringkultivars gebaseer op daglengte- en vernalisasiereaksie | Joubert, G. D. | 1985 |
KeywordsCold requirement, photoperiod, vernalization, wheat AbstractDie koue- en daglengtereaksies van koringkultivars in groeikaste is ondersoek as aanduiding van die produksiegebiede waar die betrokke kultivars sal aanpas. Die resultate toon dat die 24 koringkultivars wat ondersoek is, uiteenlopende koue- en daglengtereaksies vertoon. Klassifikasie van die kultivars op grond van hierdie inligting het goed ooreengestem met die nasionale kultivar-aanbevelings wat grootliks op die opbrengsprestasie In kultivarveldproewe gebaseer is. S.-Afr. Tydskr. Plant Grond 1985, 2: 120–122 AuthorsJoubert, G. D. Year Published1985 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1985.10634150 This article contributed by:
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| Geographical variation in the seasonal moth flight activity of the maize stalk borer, Busseola fusca (Fuller), in South Africa | van Rensburg, J.
B.J. | 1985 |
KeywordsBusseola fusca, maize stalk borer, survey AbstractThe seasonal abundance of Busseola fusca moths at five localities in the maize production area of South Africa was monitored by means of Robinson light traps. Geographical variation in the flight pattern was shown to exist between localities from east to west. Both the time and magnitude of the three seasonal moth flights seem to be governed by climatic factors. It is pointed out that the severity and the time of occurrence of larval infestations in different localities are largely predetermined by the time of planting. S. Afr. J. Plant Soil 1985, 2: 123–126 Authorsvan Rensburg, J.
B.J., Walters, M. C. and Giliomee, J. H. Year Published1985 PublicationSouth African Journal of Plant and Soil Locations- Bethal, South Africa (-26.45, 29.467)
- Vereeniging, South Africa (-26.683, 27.917)
- Potchefstroom, South Africa (-26.733, 27.083)
- Delareyville, South Africa (-26.533, 25.5)
- Bethlehem, South Africa (-28.167, 28.3)
DOI10.1080/02571862.1985.10634151 This article contributed by:
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| Die rol van koolhidraatreserwes by kwekeryprestasie van appelhardehoutsteggies | Stassen, P.
J.C. | 1985 |
KeywordsApple cuttings, Merton 793, survival AbstractSterk eenjarige winterlote van 'n tien-jaar-oue Merton-793-moederplantasie is opgedeel in steggies van 30 cm lengte. Die basale steggie is gesny vanaf die punt van aanhegting, met die tweede en derde steggie in opeenvolgende posisies nader aan die lootpunt. Die posisie van steggies op die loot het geen verskil in bewortelings- persentasie voor bot tot gevolg gehad nie. Verskille in persentasie oorlewing tussen steggies vanaf verskillende lootposisies is egter verkry nadat steggies toegelaat was om te bot en te groei. Hierdie verskille het verband gehou met die werklike hoeveelhede koolhidrate wat die steggies bevat het. S.-Afr. Tydskr. Plant Grond 1985, 2: 127–129 AuthorsStassen, P.
J.C. Year Published1985 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1985.10634152 This article contributed by:
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| Yield assessment of advanced wheat breeding lines the Winter Rainfall Region of South Africa. I. Homogeneity of the region | Marais, G. F. | 1985 |
KeywordsBreeding, specific and general adaptation, wheat AbstractThe major wheat-producing areas in the Winter Rainfall Region are geographically divided into the Rûens and Swartland. The question whether the Rûens and Swartland should be regarded as non-similar areas, each meriting its own wheat-breeding programme, is considered. Correlations between cultivar means obtained in the two regions, interaction variance components, the nature of patterns regarding yield at different flowering dates and the similarity in choice of cultivars by farmers in the two areas, all sėem to point to a high degree of similarity. It is concluded that it may not be worth while to conduct separate breeding programmes. S. Afr. J. Plant Soil 1985, 2: 130–134 AuthorsMarais, G. F. Year Published1985 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1985.10634153 This article contributed by:
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| Yield assessment of advanced wheat breeding lines in the Winter Rainfall Region of South Africa. II. Choosing representative trial sites | Marais, G. F. | 1985 |
KeywordsBreeding, trial sites, wheat, yield testing AbstractAn evaluation of the present system of testing of advanced wheat lines was made in terms of expected genetic gain from selection. Indications are that this system can function quite effectively if properly managed. The feasibility of substituting high potential test sites for low potential test sites in order to facilitate yield testing was also investigated. It was concluded that it may be more appropriate to select test sites on the basis of production intensities, predominant soil types and annual rainfalls. One such solution was derived and is proposed for implementation in the Winter Rainfall Region. S. Afr. J, Plant Soil 1984, 2: 135 −140 AuthorsMarais, G. F. Year Published1985 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1985.10634154 This article contributed by:
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| Die invloed van fosfor, nitraat en ammonium op die opname en vervoer van stikstof en fosfor en op die groei van koring | Claassens, A. S. | 1985 |
KeywordsNitrogen, N uptake, phosphorus, P uptake, P toxicity, wheat. AbstractIn 'n waterkultuureksperiment met koring is die invloed van verskillende P-toedienings (0,02 tot 5,0 me H2PO4 dm−3) en van verskillende NH4:NO3-verhoudings (0:15 tot 12:3) met 'n Hoagland-voedingsoplossing (no. 2) as kontrole bestudeer. Normale groei is reeds by 'n laer P-voorsiening (0,2 me dm−3) as die kontrole (1,0 me dm−3) verkry. Die hoogste P-voor-sieningsvlakke het opbrengs verlaag by die laagste NH4: NO3-verhoudings. Beter opbrengs is verkry met intermediäre NH4:NO3-verhoudings, waarvoor hoër P-voorsiening noodsaaklik was. By hoë P-voorsiening het chlorose-simptome tussen die blaarnerwe voorgekom wat vererger het met hoër NH4:NO3-verhoudings. Plantontledings dui daarop dat behalwe by die hoogste NH4: NO3-verhouding, die chlorose-simptome toegeneem het met hoër P-status in die bogroei. Die teenoorge- stelde tendens het ten opsigte van die P-status in wortels voorgekom. By hoë P-voorsiening is dit moontlik dat NO3 die vervoer van P vanuit die wortels na die bogroei verminder en gevolglik die simptome wat met hoë P-status in die bogroei geassosieer word, verminder. Die N-status van die bogroei het verhoog van die laagste na die hoër P-voorsiening. Hierdie verhoging was meer wanneer slegs NO3 voorsien is, as wanneer NH4 en NO3 voorsien is. Hieruit is afgelei dat P-voorsiening minder kritiek is vir N-opname as beide NH4 en NO3 voorsien word. S.-Afr. Tydskr. Plant Grond 1985, 2: 141 −145 AuthorsClaassens, A. S. and Fölscher, W. J. Year Published1985 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1985.10634155 This article contributed by:
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