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Stutterheim, South Africa

Mzini L.L.,Dohne Agricultural Development Institute | Winter K.,University of Cape Town
Water SA | Year: 2015

In the search for alternative and reliable water sources to irrigate vegetables for backyard gardens, an experimental field was set up in the vicinity of the Umtata Dam, north-west of the town of Umtata, to test grey-water quality and its effects on soil nutrient content following 4 successive growing seasons. Samples of grey-water that were generated from informal housing adjacent to the Umtata Dam were collected from kitchen and bath tubs/washing basins. These samples were analysed before being used for irrigating vegetable crops. Te results showed that grey-water quality was ‘fit for purpose’ for irrigating edible vegetable plants. Although the average Na+ (16 mg/ℓ) and Cl- (15 mg/ℓ) ions were significantly higher (p = 0.05) for grey-water than other treatments, both were below the limit of 100 mg/ℓ set in the South African Water Quality Guidelines. Te concentrations of nutrients and heavy metals found in the grey-water samples were significantly lower compared to the World Health Organization guidelines for the safe use of grey-water and within the target water quality range (TWQR) prescribed by South African guidelines for irrigation water. However, the study strongly recommends that grey-water be diluted in order to lower the salt content and to improve the irrigation water quality. Results from an analysis of soil samples showed no significant differences in pH as a result of applying grey-water throughout the soil profile of up to 90 cm depth. Na content of the soil irrigated with grey-water was not significantly different than that of plots where diluted grey-water and potable water were used. Therefore, the grey-water used in this study does not appear to cause an accumulation of salts and heavy metals in soil, in the short term. © 2015,South African Water Research Commission. All rights reserved. Source


Ntwana B.,Stellenbosch University | Ntwana B.,Dohne Agricultural Development Institute | Agenbag G.A.,Stellenbosch University | Langenhoven P.,ASNAPP
South African Journal of Plant and Soil | Year: 2011

The study was conducted at eleven sites in the Cederberg Mountains, about 200 km north of Cape Town, during March 2006, to gain some information on soil characteristics of natural habitats of Buchu (Agathosma betulina) and determine possible variations in Buchu oil quality at different sites. Plant samples were collected and plant height was recorded at each site. Soil samples were taken as close as possible to the sampled plants, while the direction of the slope was also recorded. The soil analyses indicated that soils of the Cederberg Mountains are mostly very sandy with low levels of nutrients. The pH of the soil was found to vary between pHKCl 3.7and 5.3. Plant height varied with age and between sites and the analyses of the leaves indicated low levels of most of the inorganic elements. Essential oil from the sites showed slight variations, but generally low pulegone levels, high levels of diosphenol and the absence of measurable amounts of cis-trans acetylthio-p-menthan-3-one isomers indicated that all the material originated from pure A. betulina genetic material. High levels of diosphenol also indicated that the material was from diosphenol chemotype. Source


Nyangiwe N.,Dohne Agricultural Development Institute | Nyangiwe N.,Stellenbosch University | Harrison A.,University of Pretoria | Horak I.G.,University of Pretoria | Horak I.G.,University of the Free State
Experimental and Applied Acarology | Year: 2013

The objective of the study was to establish to what extent the native tick species Rhipicephalus decoloratus has been displaced by the invasive introduced tick, Rhipicephalus microplus at two communally grazed areas in the Eastern Cape Province, South Africa. To this end ticks were collected monthly from five cattle over a period of 2 years and from 10 drag-samples of the vegetation over a period of 1 year at each locality. Whereas 10 years previously only R. decoloratus and no R. microplus had been recorded in the vicinity of the two sites, R. microplus now comprised the bulk of collections at both. Furthermore, significantly more R. microplus were collected from cattle at both localities during the 2nd year of the survey than during the 1st. In addition to 83 instances of intraspecific coupling, there were 17 instances of R. microplus males coupled with R. decoloratus females. Collections made from cattle and goats on two farms close to the study sites revealed that R. microplus was present on both host species and that it significantly outnumbered R. decoloratus on one of the farms. Rhipicephalus decoloratus and R. microplus larvae as well as larvae exhibiting characteristics of both species were collected from the vegetation. © 2013 Springer Science+Business Media Dordrecht. Source


Mzini L.L.,Dohne Agricultural Development Institute | Winter K.,University of Cape Town
South African Journal of Plant and Soil | Year: 2015

Research on the use of greywater for irrigation has focused attention largely on greywater quality and biomass of the crop, but not on the quality of edible vegetable crops, whereas aesthetical appeal of the vegetables determines the acceptance in fresh produce markets. Thus a field experiment was established at the Umtata Dam Research Station where combinations of cabbage and onion, spinach and beetroot, and carrot and lettuce were planted to coincide with four different planting seasons. Crops were irrigated with greywater generated from household activities such as bathing and dishwashing, diluted greywater (1:1 with potable water), and potable water from a tap stand. The yield and aesthetical appeal were measured. There were significantly higher yields and aesthetical appeal of cabbage from using diluted greywater. Onion yields were significantly higher when irrigated with greywater. Similarly, spinach had significantly higher yields but many leaves were infested with leaf-spot disease, which significantly lowered its marketability from greywater treatment. Beetroot yield was reduced by 47% (4.7 t ha-1) when irrigated with greywater compared to the control and external quality was not affected by any of the three water treatments. Carrot also did not show any significant difference in yield, but carrots that were irrigated with potable water were significantly more appealing. Lettuce irrigated with diluted greywater was significantly more appealing than other treatments. Crops that were irrigated with greywater resulted in higher yields, but compromised the quality of the crop to meet fresh produce market requirements. © 2015 © Southern African Plant & Soil Sciences Committee. Source


Goni S.,Dohne Agricultural Development Institute | Goni S.,Stellenbosch University | Muller C.J.C.,Research and Technology Development Services | Dube B.,Stellenbosch University | Dzama K.,Stellenbosch University
Tropical Animal Health and Production | Year: 2014

Milk production parameters of purebred Jersey (J) cows and Fleckvieh × Jersey (F × J) cows in a pasture-based feeding system were compared using standard milk recording procedures. Milk, fat and protein production was adjusted to 305 days per lactation and corrected for age at calving. Effects of breed, parity, month and year were estimated for milk, fat and protein yield as well as fat and protein percentage, using the general linear model procedure. Fixed effects identified as affecting milk production parameters significantly were breed, parity and year. F × J cows produced significantly more milk than J cows (6141 ± 102 and 5398 ± 95 kg milk, respectively). Similarly, fat and protein yields were significantly higher in F × J (272 ± 4 and 201 ± 3 kg, respectively) than in Jersey cows (246 ± 3 and 194 ± 2 kg, respectively). Fat and protein percentages only differed slightly in absolute terms being 4.61 ± 0.04 % fat in the Jersey compared to 4.47 ± 0.04 % fat in the F × J. Protein levels for J and F × J cows were 3.62 ± 0.03 and 3.51 ± 0.03 %, respectively. Despite a lower fat percentage, F × J crossbred cows may be more productive than purebred Jersey cows which may be due to heterotic effects. © 2014, Springer Science+Business Media Dordrecht. Source

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