HM Medical Clinic

Programme/sub-programme/section

PROGRAMME: TECHNOLOGY, RESEARCH AND DEVELOPMENT SERVICES
DIRECTORATE: PLANT SCIENCE
A. PROGRAMME & PROJECT LEADER INFORMATION
Programme leader
Project leader (Researcher)
Title, initials, surname
Present position
Specialist Agricultural Scientist Specialist Agricultural Scientist Corresponding Author
Office Address
Room B1-11 First Floor Room B1-11 First Floor Tel numbers
Office: 0218085279
Office: 0218085279
Fax: 0218085331
Fax: 0218085331
Cell: 0837242970
Cell: 0837242970
E-mail address
[email protected] [email protected] PROJECT PURPOSE
Research
Training
Academic
Contract
For degree purposes
PROJECT INFORMATION
Project title
The evaluation of potential inter row cover crops for weed suppression in rooibos production systems Keywords
conservation farming, inter row cover crop mixtures, weed Start date
1. Problem identification, objectives and aims

Rooibos tea is uniquely South African and grows natural y in the Cederberg and Suid-Bokkeveld regions of the Western and Northern Cape, respectively. Rooibos (Aspalathus linearis (Burm. F) Dahlg., Fabaceae) is commercial y important as a natural health drink both local y and abroad. Currently, rooibos tea is both cultivated and harvested from wild populations. Cultivation in plantations yields the vast majority of production with only about 1% harvested from the wild (CI, 2008). The leaves are processed and used to make rooibos tea. A large part of marketing rooibos tea depends on its characteristics as a natural health drink (Herbst, 2009). Tea made from the rooibos plant has a growing market local y and global y, including the United States, Canada, Europe and Japan, because it contains healthy antioxidants and no caffeine (Anonymous1, 2008). In addition, the Fynbos biome is characterised as a biodiversity hotspot, as it has the greatest non-tropical concentration of higher plant species in the world (CI, 2013). This makes rooibos tea a unique product, the availability of which strongly depends on this area alone. Under the threat of climate change and the resultant instability of agricultural production and market forces, the sustainability of the rooibos industry is in question (Pretorius, 2008). Hansen (2006) reported that a strong need among rooibos producers is for research to be undertaken in order to determine the requirements for sustainable production of rooibos. However, to date, certain aspects such as the use of cover crops had been overlooked. The aim of this research project wil therefore be to study the interactions of leguminous/grass cover crops mixtures on weeds, using serradel a, lupine, vetch, barley, oats and rye, on the population of natural weed infestations and rooibos plant production. In addition, with the expected increase in living organisms due to higher levels of plant material, the number and type of pests and diseases wil also be studied. The major goal of this research wil ultimately be to provide rooibos producers with scientific information on how to grow cover crop mixtures in an integrated weed management system. 2. Rationale (motivation) - Hypothesis
According to Storkey (2008), successful long-term weed management requires a shift from simply control ing problem weeds with in-crop herbicides to agricultural production systems that are redesigned to manage weeds at al stages of their life cycle. Such systems should restrict weed emergence, reduce weed growth and reproduction, and minimise weed competition with crops. Research in the last decade has documented that management practices such as reduced til age, diverse crop rotations, competitive cultivars, higher crop seed rates, altered seed dates, specific fertiliser placement and timing, intercropping, silage crops, and green manure or cover crops can effectively manage weed populations, especial y when used in conjunction with targeted, but limited herbicide use. Research has also clearly indicated that the effectiveness and consistency of these non-herbicide weed management practices greatly increases when three or more of these practices are simultaneously employed. Once these integrated weed management systems are implemented, herbicides can then be used in a more targeted and sustainable manner, preserving their usefulness for decades to come (Storkey, 2008). In addition to sustainability and climate change, the rooibos production systems has to be compliant and adhere to the requirements of human activities as it is in close proximity to the biodiversity hotspot adjacent to it. According to Pretorius (2008) there are more general benefits from practising biodiversity conservation that are worth bearing in mind. The basic elements of these are: Management of natural resources – conserving natural resources guards against the depletion of natural resources resulting from pol ution, desertification, over exploitation etc. al owing for the sustainable delivery of ecosystem services on which agricultural production is dependant. To achieve this it is necessary to implement more sustainable agricultural practices; Conserving the gene pool – resilience of any species to changes in the physical environment (like climate change) is enhanced by diversity. Rooibos demonstrates high diversity within the species, and grows in a wide range of habitats with widely differing rainfal and temperature regimes. With the reality of climate change, conserving the diversity of this genetic resource wil provide a wider range of options for maintaining production in the future and is an economic necessity for the industry. c) Decreased input costs – maintaining the biodiversity on farms wil ultimately reduce input costs due to maintaining organic matter in the soil, integrated pest management and long term production. d) Compliance with legislation – given the international focus on sustainability, compliance with environmental and agricultural legislation wil become vital to doing business. Non-compliance not only leads to il -informed unsustainable production practices but wil increase input costs, limit expansion and could deny access to key markets. Further, there is a realisation that agriculture is a mix of environmental as wel as economic and social concerns. This awareness has led a move towards the concept of sustainability in farming practices. The concept centre around the need to build farm productivity and profitability in a way that protects the natural resources on the farm as wel as social wel -being; ensuring a sustainable agricultural sector that can meet current and future world food demands (Pretorius, 2008). Farmers can attain higher levels of productivity and profitability through improving soil health and the environment. These outcomes can be achieved through the adoption and implementation of conservation agriculture principles and practices. Agronomic strategies for conservation agriculture aim at harnessing the abundant and diverse life forms that exist within soils to enhance their long-term productivity. Some combinations are:  Non-inversion weed control, including the use of al elopathy and smother crops; Increase in biomass inputs to soil systems; Ecosystem-based and integrated management methods to control weeds, pests and diseases (United Nations FAO, 2008). Cover crop mixtures of grasses and legumes are being investigated for their ability to suppress weeds and improving soil quality through increasing the available nitrogen levels and organic matter content. Besides offering an alternative method to combat weeds, it may also reduce soil erosion, especial y wind erosion, in the rooibos producing areas. This research on cover crops wil also encompass other combinations proposed by the FAO, namely increased biomass in inter rows and integrated management of weeds by smother cropping and mulching. Cover cropping with competitive species is an attempt to starve weeds of light, nutrients, moisture and space. Smothering of weeds in this way, may deplete its carbohydrate reserves and lessen weed pressure by slowing growth and reducing seed production. Fast-growing, high-biomass species make good cover crops because they can get a head start on weeds (Grubinger, 2002). In addition, cover crops can improve the soil by adding organic matter, nutrients and stability and by acting as scavengers to trap excess nutrients that otherwise might leach out of the soil (cropsoil.psu.edu/extension/ct/uc128.pdf). It also builds soil organic matter and provides a way to build up mineral and soil biological levels, setting the stage for a few years of excel ent crops and reduces weed numbers in fol owing years for improved herbicice efficacy. According to Buhler (1997), a successful cover crop system must have at least three key characteristics: flexibility, consistency, and adaptability. Other important aspects include life cycle, seeding date and rate, winter hardiness, nitrogen fixation or scavenging ability, feed or forage value, and establishment costs (cropsoil.psu.edu/extension/ct/uc128.pdf). As more and more food is traded global y, governments are struggling to monitor and manage the safety of their food supplies. Typical y, they impose new barriers to entry in the form of public standards such as import bans. In some cases, governments resort to regulations such as the US bioterrorism laws and the EU's Maximum Residue Levels or GMO restrictions. Along with new standards to address safety, environment, and ethics have come new verification or certification criteria. A broad range of standards exists that are focused primarily on protection of ecological systems and the assurance of limited toxic chemicals (Anonymous2, 2008). With human population growth and the accompanying shifts in standards of living continuing into the 21st century, people are likely to spend more on luxury products (Southgate et al., 2007). The demand for products believed to possess health promoting properties, or perceived as being a healthy alternative to conventional products, could increase greatly. One such a product is rooibos tea, which occurs endemical y in the south western part of South Africa. As yet, certain mountainous parts of the Western Cape, are stil the only place in the world where rooibos tea is cultivated commercial y at a significant scale (Hansen, 2006). One of the major impacts of this project wil be the opportunities provided at farmer's days to introduce the concepts of plant interference-based pest, disease and weed management systems to a broad audience. The feedback and suggestions obtained at the rooibos farmer's days of the Western Cape wil refine cultivation of inter row cover crop mixtures of grasses and legumes. Eventual y it could make a contribution to integrated weed suppression for improved conservation farming and sustainable rooibos production. 3. Literature review
Rooibos (A. linearis subsp. linearis) is like member of thefamily of plants growing in The leaves are used to make cal ed red tea, bush tea (esp. Southern Africa), redbush tea (especial y the UK), South African red tea, or simply rooibos. The product has been popular infor generations and is now consumed in many countries (Marnewick et al., 2011). It belongs to the Aspalathus plant group that consists of 278 species (Malgas & Oetle 2007). Rooibos is grown only in a relatively smal area in theProvinces General y, the leaves are oxidised, a process often, inaccurately, referred to asby analogy withterminology. This process produces the distinctive reddish-brown colour of rooibos and enhances the flavour. Rooibos is becoming more popular in particularly among health-conscious consumers, due to its high level of (Theunissen, 2005). Rooibos also contains a number of (Krafczyk et al., 2009). Traditional medicinal uses of rooibos in include al eviating infantile al ergies,and dermatological problems. (Joubert et al., 2008). A high intake of rooibos tea resulted in significant reductions in lipid peroxidation, LDL cholesterol, triglycerides, and an increase in HDL cholesterol levels compared with the control group and therefore, lowering risk factors (Marnewick et al., 2011). Rooibos requires deep sandy, wel -drained soil. Quality improves with an increase in altitude, mineral content and lower temperatures, with the highest grade produced in the mountainous areas and the lowest grade in the Sandveld. Wild harvesting occurs mostly in the South Bokkeveld and Wupperthal areas and forms only a very smal fraction of the industry's total annual harvest. Unsustainable wild rooibos harvesting techniques, together with poor rooibos cultivation planning threaten the wild genetic stock of rooibos, which wil become ever more important for its potential pest and drought resistant properties in the face of climate change (Pretorius, 2008). About 36 000 ha of rooibos is currently planted in the Western Cape. Compared to 14 000 ha planted in 1991, it is clear that the industry has grown dramatical y since then. The current footprint is 60 000 ha as crops are rotated with a minimum rest period of two years. There are roughly 450 rooibos producers, yielding a crop of approximately 15 000 tons. Annual sales are in the region of 11 000 tons of which 6000 tons are exported. Currently 95% of exports are in bulk. Nearly al the rooibos tea brands found on South African supermarket shelves and in the fast-growing international markets, are produced from cultivated rooibos. The opening up of export markets and the appeal of rooibos to health-conscious northern consumers have led to huge expansions in rooibos production in the Greater Cederberg area and driven the expansion of rooibos plantations into the natural habitat of wild rooibos. Rooibos occurs mainly in three vegetation types: Cederberg Sandstone Fynbos; Bokkeveld Sandstone Fynbos and Olifants Sandstone Fynbos (Pretorius, 2008). The rooibos plant has an average lifespan of 6 years which equates to 4 crops in its average lifetime. Good agricultural practice includes a rest period of 2-3 years of a particular field before re-planting, and in a ful cycle (growing period plus rotation period) an average lifetime yield of 3000 kg/ha, i.e. 375 kg/ha/annum is obtained. Rooibos is grown in both the Succulent Karoo and Fynbos biomes, from Nieuwoudtvil e in the north and the Bokkeveld in the east to the Sandveld in the west and south. Climate change is leading to lower rainfal and higher temperatures and this, in conjunction with the growing market demand and limited area suitable for rooibos production has led to the industry expanding its footprint to the southwest with major growth in the Sandveld area as wel as the Nieuwoudtvil e area (Pretorius, 2008). Several factors contribute to climate change, the most important of these being our emissions of greenhouse and ozone-depleting gasses. It cannot be denied that human activity is responsible for almost 45% of current global CO2 emissions (Anonymous3, 2008). Rooibos tea is commonly marketed as being caffeine free, rich in antioxidants and containing minerals. While an increase in the output per unit area is likely to be achievable, farmers have up to now been more likely to try and increase production by simply expanding the surface area of production, especial y considering that rooibos tea grows in conditions not suited to most other crops. Of course, all of this takes place in the context of environmental issues such as habitat loss, species extinctions and climate change, to name but a few. Al of these problems wil place constraints on what constitutes wise and sustainable use of natural resources by the rooibos industry. Several sources of motivation are becoming strong influences in the drive towards more environmental y sustainable practices – practices that are aimed at minimising harm to biodiversity or endangering ecosystem structure and function, with their accompanying valuable ecosystem services. International pressure, not only from international agreements such as the Convention of Biodiversity, but also the changes in sentiment of markets towards practices that are perceived to be environmental y friendly, contribute to the increasing need for sustainable production in al agricultural types, including rooibos tea. During interviews, rooibos farmers cited minimal disruption of nature, for example by means of minimum til age and correct crop rotation as aspects they need more information on (Smit, 2010). Benefits of sustainable rooibos production include risk management, managing natural resources, decreased input costs, conforming to legislation, strategic positioning with the SA government, generic marketing opportunity, competitive advantage in key markets and expanding markets to increasingly aware consumers. Sustainable production is of growing importance in international markets with the EU moving towards sustainable production as a buying requirement for imported products. Most of the world's biggest supermarket chains have committed to sustainable development and using sustainable production as a buying criterion. A local example is The Biodiversity & Wine Initiative which has facilitated negotiations between Wines of South Africa and Walmart, the biggest supermarket group global y, potential y opening up a huge market (Hansen, 2006). 4. Potential beneficiaries

The knowledge gained in this study wil further our capacity to structure environmental y
friendly weed suppressive practices, which wil typically be applicable to smal -scale and
commercial rooibos farmers.
5. Technology development

Introduce the concept of inter row mixed grass/legume cover crops' cultivation as a plant
interference-based weed management system, at farmer's days from 2013-2018. The
production practice of inter row mixed grass/legume cover cropping for weed control
may be easily incorporated into existing rooibos production systems as the same planting
equipment and techniques may be used. No agricultural chemical spraying wil be
required but some phosphorus application might be required by leguminous cops
depending on soil analyses. Ten weeks after planting, the smother crop could either be cut
or rol ed during September to form plant residue mulches to improve soil health and fertility.
It may also be left without any additional treatment to maturity to form dry mulch.
16. Persons participating in the project (list internal and external collaborators)
[email protected] Directorate Plant Science, Agriculture [email protected] Directorate Plant Science, Agriculture [email protected] Directorate Plant Science, Agriculture [email protected] Directorate Plant Science, Agriculture
(1)Race:
= African, Coloured or Indian (2)Gender: F
(3)Position: Co = Co-worker (other researcher at your institution)
Coll = Collaborator (participating researcher that does not receive funding for this project from industry) PF = Post-doctoral fellow Pr L = Programme leader PL = Project leader RA = Research assistant / student TM = Team member TA = Technical assistant / technician Budget for the first year:
Other funders
(insert names)*
PROJECT FUNDING REQUIRED FOR 1ST YEAR: TOTAL Personnel costs
Running costs
Equipment (capital items)
Appendix A
3. Literature review
Anonymous1. 2008. CAPE Biobusiness brochure, Cape Town. Anonymous2. 2008. World Export Development Forum, Montreux, Switzerland. Anonymous3. 2008. United Nations Framework Convention on Climate Change, New York. Buhler, D.D., Hartzler, R.G. & Forcel a, F. 1997. Implications of weed seedbank dynamics to weed management. Weed Sci. 45: 329-336. CI. 2013. Conservation International, Biodiversity Hotspots, Cape Floristic Region, Grubinger, V. 2002. Weed management on organic vegetable farms. Univ. Vermont Ext. USA. Hansen, T. 2006. Sustainable Rooibos Initiative: A Sustainable Production Strategy For The South African Rooibos Tea Industry. Report Commissioned By Capenature (Greater Cederberg Biodiversity Corridor) & SA Rooibos Council. Cape Town. Herbst, M. 2009. Ecosystem functioning, ecosystem services and rooibos production as affected by connectivity to natural vegetation and pesticide use in rooibos tea (Aspalathus linearis) farming. Progress report, CIRAD-UCT Col aboration, Dept of
Botany, University of Cape Town. Cape Town.

Joubert, E., Gelderblom, W.C.A., Louw, A., De Beer, D. (2008). "South African herbal teas: Aspalathus linearis, Cyclopia spp. and
Athrixia phylicoides—A review". Journal of Ethnopharmacology 119 (3): 376–412.
Krafczyk, N., Woyand, F. & Glomb, M.A. 2009. "Structure-antioxidant relationship of flavonoids from fermented rooibos". Molecular
Nutrition & Food Research 53 (5): 635–42.
Malgas, R., Oetle, N. 2007. The sustainable harvest of wild rooibos, Environmental Monitoring Group Trust. Cape Town.
Marnewick, J.L., Rautenbach, F., Venter, I., Neethling, H., Blackhurst, D.M., Wolmarans, P. & Macharia, M. 2011. "Effects of rooibos
(Aspalathus linearis) on oxidative stress and biochemical parameters in adults at risk for cardiovascular disease". Journal of
Ethnopharmacology 133 (1): 46–52.
Pretorius, G. 2008. Rooibos Biodiversity Initiative (RBI): Biodiversity Best Practice Guidelines for the sustainable production of rooibos.
Natura Libra Environmental Consultants cc, PO Box 1152, Malmesbury, 7299.
Smit, J.E.F. 2010. The Rooibos Biodiversity Initiative: relevant perspectives and needs of the producer. Department of Conservation Ecology and Entomology, Stel enbosch University, Stel enbosch. Southgate, D., Graham, D.H. & Tweeten, L. 2007. The world food economy. Blackwel , Oxford, United Kingdom. Southwood 1975. " Ecological Methods" Storkey, F. 2008. How Can Weed Management Support the Development of a More Multifunctional Agriculture? International Weed Science Congress. Vancouver. Canada. Theunissen, I. 2005 Rooibos the healthy tea. Science in Africa. United Nations. 2008. Investing in Sustainable Agricultural Intensification: The Role of Conservation Agriculture. Food and Agriculture Organization of the United Nations (FAO), Rome, Italy. Waarts, Y. & Kuit, M. 2011. Intensification and Sustainability in South African Rooibos: exploring the conditions for market-led sustainable development in a biodiversity hot spot. University of Wageningen. The Netherlands.

Source: http://www.greenagri.org.za/assets/documents-/Projects-Research/Plants/Alternatives/Rooibos.pdf