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18 February 2019 | Story Leonie Bolleurs | Photo HO de Waal
Ground spiny Cactus pear
Shredded, sun-dried, and coarsely ground spiny cactus pear (Opuntia ficus-indica and O. engelmannii), ready to be included in balanced diets for ruminant livestock (cattle, sheep, goats) and wild antelopes.

Prof HO de Waal, researcher in the Department of Animal, Wildlife and Grassland Sciences at the University of the Free State (UFS), has developed a standard procedure for the processing of spiny cactus pear (Opuntia spp.) into livestock fodder. This will ultimately assist in the management of massive infestations of spiny cactus pear and help to convert underutilised farmland back to natural grazing land.

In addition to applying biological control agents, mechanical control is used to harvest alien spiny cactus pear, and the large volume of material is processed as livestock feed.

 

Introduced to South Africa

 

Three hundred years ago, seafarers visiting the Cape of Good Hope introduced the well-known invading alien spiny cactus pear to South Africa. These were later transported inland and by the 1950s about one million ha of South Africa had been invaded by the alien cacti.

Some regions in the Eastern Cape have been taken over by dense, impenetrable thickets of these cacti. Invasive alien plants (IAPs) such as cacti pose a direct threat to, among others, South Africa’s water security and productive use of land.

A range of methods is used to control IAPs, including mechanical, chemical, biological, and integrated control methods.

A control programme must include the three phases of initial control to drastically reduce the existing population; follow-up control of seedlings, root suckers, and coppice growth; and maintenance control on an annual basis to sustain low alien plant numbers.

 

Processing spiny cactus pears

 

According to Prof De Waal, the harvesting and processing of the spiny cactus pear is fairly simple. Although it requires a good measure of physical strength, perseverance, and the necessary protective clothing, the cacti can be processed by harvesting the plants; shredding the cladodes through a cladode cutter; then drying them in the sun, and lastly grinding it in a hammer mill. “The long spines are degraded mechanically by grinding the sun-dried cladode strips in a hammer mill before including it in balanced livestock diets,” said Prof De Waal.

Infestations will be opened, reclaimed, rehabilitated and the natural pastures (veld) allowed to revert back to grazing for livestock.

The National Resource Management Programme (NRM)P) will be approached for official support in clearing and rehabilitating massive areas of infestation by alien spiny cactus pear in the Eastern Cape. Such financial support will be an investment in reducing the infestation by invaders and the rehabilitation and sustainable use of natural resources in South Africa.

News Archive

Shack study holds research and social upliftment opportunities
2015-02-10

Photo: Stephen Collett

When Prof Basie Verster, retired head of the Department of Quantity Surveying at the University of the Free State (UFS), initiated an alternative form of housing for Johannes - one of his employees - a decision was made to base research on this initiative. This research project in Grasslands, Heidedal focused on the cost and energy efficiency of green and/or sustainable shacks.

Esti Jacobs from the Department of Quantity Surveying, together with an honours student in Quantity Surveying, a master’s student in Architecture, and young professionals at Verster Berry, helped with the project.

The physical goals of the project were to create a structure that is environmentally friendly, and maintains a comfortable interior climate in winter and summer, as well as being cost-effective to erect. The structure also had to be socially acceptable to the family and the community.

“The intention was to make a positive contribution to the community and to initiate social upliftment through this project. Structures such as the ‘green shack’ may serve as an intermediate step to future housing possibilities, since these structures are relatively primitive, but have economic value and could be marketable,” she said.

Esti explains the structure of the building, which consists of gum poles and South African pine bearers, with a timber roof and internal cement block flooring. The building is clad with corrugated iron and has a corrugated iron roof finish. Additional green elements added to the structure were internal Nutec cladding, glasswool insulation in walls, internal gypsum ceiling boards with ‘Think Pink’ insulation, internal dividing wall and door, polystyrene in the floors, and tint on the windows. A small solar panel for limited electricity use (one or two lights and electricity to charge a cellphone) and a Jojo water tank for household consumption by the inhabitants were also installed.

Esti said: “Phase one of the research has been completed. This phase consisted of an investigation into the cost of an alternative form of housing structure (comparing traditional shacks with the planned structure) as well as the construction process of the physical housing structure.

“Phase two of the research, commencing in February 2015, will last for two to three years. This phase will include the installation of temperature and relative humidity logging devices inside the existing traditional shack and the new green shack. The logs will be regularly monitored by the UFS Department of Quantity Surveying and Construction Management.

These data will enable the researchers to measure the differences in comfort levels inside the two different structures. The data, together with other information such as building materials and methods, are then processed by software programs. Through the simulation of different environments, building materials, and alternate forms of energy, software models can be used to come up with conclusions regarding more energy-friendly building materials and methods. This knowledge can be used to improve comfort levels within smaller, low-cost housing units.

The UFS will be working with Prof Jeff Ramsdell of the Appalachian State University in the USA and his team on the second phase of the project.

“This research project is ongoing and will be completed only in a few years’ time,” said Esti.

The results of the research will be published in accredited journals or at international conferences.

 

For more information or enquiries contact news@ufs.ac.za.

 

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