| Measurement of exchangeable aluminium in soils and clay minerals by isotopic exchange | Kotzé, W.
A.G. | 1984 |
KeywordsExchangeable aluminium, isotopic exchange, clay minerals AbstractIsotopically exchangeable Al was determined in soils and clay minerals by equilibration with 28Al. Best results were obtained with a weak extractant and an equilibration time of eight min. The calculated amount of isotopically exchangeable Al was independent of the amount of carrier-Al added with the 28Al. In some soils isotopically exchangeable Al did not appear to be related to the amount of Al which could be extracted by various electrolyte solutions. This technique provides an improved means of studying the exchange reactions of Al in acid soils and clay minerals. S. Afr. J. Plant Soil 1984, 1: 57–60 AuthorsKotzé, W.
A.G., Joubert, Marlise, de Villiers, Johannes. F., van der Westhuizen, M. and van der Bank, D. Year Published1984 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1984.10634110 This article contributed by:
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| Pedogeomorphic aspects of the Roodepoort area, Transvaal: Soil depth-slope relationships | Munnik, M. C. | 1984 |
KeywordsPedogenesis, geomorphology, soil formation, soil depth-slope relationships AbstractFifty hillslope profiles with associated soils in the Roodepoort area, Transvaal, were examined to determine the relationships between soil depth and hillslope characteristics. A meso-scale approach was adopted which implied the relationship between three soil depth phases and the hillslope units on a scale of 1:10 000. Although anomalies occur, it was found with the aid of statistical techniques, that a definite trend exists between soil depth and slope gradient. For the less than 8% slope class, soil depth variations could be ascribed to differences in parent rock and position in the landscape, whereas for slopes steeper than 8% slope, gradient apparently becomes the dominant determinant of the shallow soil depth. Because the soil depth-hillslope relationships were sufficiently well established by this study, it enabled the construction of three models to represent the varied conditions of the Roodepoort area. S. Afr. J. Plant Soil 1984, 1: 61–66 AuthorsMunnik, M. C., Verster, E. and van Rooyen, T. C. Year Published1984 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1984.10634111 This article contributed by:
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| Factors affecting the activity of atrazine in plants and soil | Nel, P. C. | 1984 |
KeywordsAtrazine, phytotoxicity, atrazine fixation and release in soil, environmental factors AbstractAvailable research findings concerning (he activity of atrazine in the plant and soil are presented in a brief review. The role of the environment is emphasized. This review is supplemented by recent research results of the University of Pretoria concerning evaluation of soil characteristics as a norm for the prediction of atrazine activity in turf soils, the comparison of a few maize hybrids with respect to their resistance towards atrazine and the influence of moisture and temperature on atrazine activity in light-textured soils. Guidelines for future research and for the use of atrazine are given. S. Afr. J. Plant Soil 1984, 1: 67–72 AuthorsNel, P. C. and Reinhardt, C. F. Year Published1984 PublicationSouth African Journal of Plant and Soil Locations- University of Pretoria, South Africa (-25.7542, 28.2308)
- Standerton, South Africa (-26.9473, 29.2469)
- Crecy, South Africa (-24.6318, 28.8442)
- Redhill, South Africa (-26.2592, 30.8298)
- Towoomba, South Africa (-24.9, 28.3333)
DOI10.1080/02571862.1984.10634112 This article contributed by:
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| The soil seed bank under nasella tussock infestations at Boschberg | Joubert, D. C. | 1984 |
KeywordsNassella tussock, Stipa trichotoma, soil seed bank AbstractNassella tussock (Stipa trichotoma Nees.) has a high annual production of seeds per plant. The total seed bank of all plants counted under a dense nassella infestation varied between 50 000 and 100 000 seeds m−2 surface area (5 cm deep) of which more than half were nassella. Seeds were recovered from soil samples by wet-sieving, chemical flotation and aspiration. Burning of the dead organic material on the soil surface destroyed about 20% of the nassella seeds present in the top layers, suggesting that this treatment could become a useful part of a control strategy. S. Afr. J. Plant Soil 1984, 1: 1–3 AuthorsJoubert, D. C. Year Published1984 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1984.10634099 This article contributed by:
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| The response of Bambara groundnut (Voandzeia subterranea) and pigeon pea (Cajanus cajan) to applications of lime, P and K | Wassermann, V. D. | 1984 |
KeywordsVoandzeia, Cajanus, lime, P, K AbstractVoandzeia subterranea and Cajanus cajan are important pulse crops in tropical and subtropical Africa and their drought hardiness and ability to utilize poor soils are inter alia reasons for this popularity. Both species hold considerable promise as crops in South Africa. The results of a pot trial and a field trial in which the responses of these two species to lime, phosphorus and potassium applications were compared with those of Vigna unguiculata, V. radiata and Arachis hypogaea are reported. The generally held belief that C. cajan is able to produce well with a minimum of fertilizer was confirmed in this investigation, particularly in the field trial where no yield responses to applications of lime, phosphorus and potassium could be measured on a rather poor soil. V. subterranea, on the other hand, responded better, particularly to lime application. Contrary to what is generally claimed in the literature, there was no indication that V. subterranea is able to produce better than the common groundnut (A. hypogaea) at low levels of soil fertility. In fact, it has to be concluded from the results that this species is not as tolerant to acid soils as the common groundnut. S. Afr. J. Plant Soil 1984, 1: 4–8 AuthorsWassermann, V. D., Kruger, A. J. and Heyns, Gillian Year Published1984 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1984.10634100 This article contributed by:
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| Nitrogen fertilization of cabbages in Natal | Richards, T. | 1984 |
KeywordsBrassica oleracea, cabbages, fertilization, nitrogen AbstractCabbage (Brassica oleracea var. capitata f. alba cv. Gloria Osena) yields were measured in two experiments on a Westleigh soil near Pietermaritzburg in response to different methods, rates and times of application of nitrogen fertilizer. Levels ranging from 0–375 kg N ha−1 were tested. The result was an almost linear increase in yield with increasing nitrogen up to the highest level applied in the first trial. In the second trial no significant increase in yield was recorded from 75 kg N ha−1 up to 375 kg N ha−1. In this trial nitrogen applied by banding and broadcasting produced similar results. There was a significantly better yield when half the nitrogen was applied before planting and half four weeks after transplanting, in comparison with all being applied before planting, or one third before planting with two top-dressings and one quarter before planting with three top-dressings. S. Afr. J. Plant Soil 1984, 1: 9–11 AuthorsRichards, T., Smith, I. E. and Bennett, R. Year Published1984 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1984.10634101 This article contributed by:
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| An analysis of the ET/Ep-curve and its application irrigation scheduling | Burgers, M. S. | 1984 |
KeywordsET/Ep-curve, irrigation scheduling AbstractThe well known sigmoidel ET/Ep -curve often quoted in the literature for a variety of crops, merely depicts a smoothed curve drawn through points representing the average ET/Ep ratio for each depletion cycle co-ordinated with the middle day of the cycle. In this form it is of little use for monitoring the water balance of a crop during periods shorter than a normal irrigation cycle. The seasonal curve can be broken down into a number of separate curves based on the actual ET/Ep ratios (fi) within each depletion cycle. From these fi-curves, hypothetical curves were derived from which cumulative soil moisture depletion up to a given day within an irrigation cycle can be deduced with ease. This approach provides a way in which the efficiency of rain precipitation can be estimated to a higher degree of accuracy so that the irrigation programme can be adjusted accordingly. S. Afr. J. Plant Soil 1984, 1: 12–16 AuthorsBurgers, M. S. and Nel, P. C. Year Published1984 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1984.10634102 This article contributed by:
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| Die rol van sekere omgewingsfaktore by alachloraktiwiteit | Reinhardt, C. F. | 1984 |
KeywordsAlachlor, clay percentage, herbicide, organic matter, soil moisture, temperature AbstractBiotoetse met graansorghum (Sorghum bicolor L.) is in potte in glashuise en groeikabinette uitgevoer. Geselekteerde grond- eienskappe is gekorreleer met alachloraktiwiteit. Organiese materiaalinhoud (% C) was die beste gekorreleerd met die aktiwiteit van alachlor en pH die swakste. Die r-waardes vir % C en kleipersentasie was 0,76 en 0,68 onderskeidelik. In meer- voudige regressie-analises is die grootste R 2 -waarde met organiese materiaalinhoud en kleipersentasie verkry. Die effek van grondvog en temperatuur op die aktiwiteit van alachlor is ook ondersoek. By 20/10, 25/15 en 30/20 °C dag/nag- temperatuurregimes was alachloraktiwiteit hoog in die grond by veldkapasiteit en versadigingspunt (2 × veldkapasiteit), maar laag in lugdroë grond. S.-Afr. Tydskr. Plant Grond 1984, 1: 17–20 AuthorsReinhardt, C. F. and Nel, P. C. Year Published1984 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1984.10634103 This article contributed by:
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| Land application of sewage sludge: Phosphorus considerations | McLaughlin, M. J. | 1984 |
KeywordsPhosphorus, sewage sludge AbstractPhosphorus considerations are gaining increasing attention where sewage sludges are applied to land because of the continuing trend of rising P levels in sludges and the growing concern for environmental pollution and nutrient recycling issues. P in sludges has reached levels comparable to inorganic fertilizers in some cases while currently average values will be in the region of 2% P (dry solids basis). In reactions with soils the soluble component (or that capable of being solubilized) will be the most important fraction. Potential benefits to be gained from sludge applied P are large while hazards from disposal of sludge P are minimal owing to the transformations which P undergoes in soils. The finite world supply of resource P and the escalating costs of inorganic P fertilizers warrants that further research be directed towards making sludges more acceptable as a source of this nutrient. Unacceptable P pollution of the environment is an added stimulus to effectively dispose of and utilize such wastes simultaneously. S. Afr. J. Plant Soil 1984, 1: 21–29 AuthorsMcLaughlin, M. J. Year Published1984 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1984.10634104 This article contributed by:
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| Evidence of a germination inhibitor in senescent soybean pod walls | Chapman, J. | 1984 |
KeywordsField weathering, Germination, germination inhibitor, Glycine max (L.) Merr., soybean AbstractWater based pod extracts of the pod wall material of four soybean cultivars were found to reduce the germination rate of mustard (Sinapis alba L.) seeds. Highly significant differences were also observed in this respect between the different pod extracts. These results indicated the presence of a germination inhibitor in senescent soybean pod walls which might provide some protection against the effects of field weathering of soybean seeds. AuthorsChapman, J. Year Published1984 PublicationSouth African Journal of Plant and Soil LocationsDOI10.1080/02571862.1984.10634105 This article contributed by:
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