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From 2011.igem.org

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Revision as of 23:54, 31 August 2011

Problem in Africa

Africa is the region most affected by desertification. Two thirds of the continent is covered by dryland which is used extensively for agricultural production. Over-cultivation has led to large scale degradation, exacerbated by frequent drought, leading to extreme food scarcity for some 650 million people who are dependent on the affected land. If the degradation trend continues, it is estimated that two thirds of Africa’s arable land may be lost by 2025 (FAO 2009).

What’s being done now

In an effort to combat desertification, 11 countries along the southern border of the Sahara are involved in the Great Green Wall project. With the help of international aid, the objective is to cover 8,000 km of dryland with vegetation as a protective barrier from erosive forces. Local governments are endorsing efforts to plant these trees. This project is also supported by the UN and EU. Planting of shrubs and trees in arid areas at risk of desertification is hugely beneficial in its ability to reintroduce soil nutrients as well as protecting the land from erosive forces. However, the operation is extremely time consuming and will take a long time before it is established.

How we can improve this

Our project will focus on distributing coated acacia seeds. African acacia trees are drought resistant species (Flagg, 1991) that provide many benefits: they can be used as a source of income as their gum is valuable. In addition, they provide shelter to small animals and protect crops from erosive forces such as rain and wind. They also restore soil fertility. Acacia trees are already commonly found in the Sahel area (Safriel et al., 2005). The benefits of planting acacias have already been demonstrated in the Acacia Operation Project, involving six sub-Saharan countries that successfully restored 13,000 hectares of land (UNCCD, 2011). The acacia genus is also one of the main plant types implemented in the Great Green Wall project.

Adequate land coverage with protective vegetation is extremely time consuming and seedlings will take time to become established and the plants need to overcome several hurdles before establishment (Figure 1).

Figure 1. Obstacles encountered throughout the acacia life cycle (Midgley & Bond, 2001).

AuxIn is a microbially enriched seed coat that improves the establishment of seedlings. This is achieved via the microbial secretion of the naturally occurring auxin, indole 3-acetic acid, which improves lateral root growth, thereby stabilising soil.

The use of seed coats has already been successfully implemented in common agricultural practice, supplying many different compounds including pesticides to plants, and will provide easy application of the product in affected areas. We are planning to develop a device that will facilitate the seeding of acacias into soil. This would eradicate the need to plant seedlings, a very time-intensive practice. This would make our product economically sound as it would save resources and time.

Production would be carried out by the AuxIn Foundation. We are planning to use similar strategies in developed countries such as the US, Australia and Israel to combat desertification and sell our project for profit in these areas. The technology can be applied to any seed type required for the area. Desertification is a global problem and we do not just want to target it on a local scale. The profits generated by this will be used to finance our efforts in combating desertification in developing countries.

Distribution will be handled by local authorities. There are many social and economic factors involved in combating desertification and we plant to address them as well as we can.

What downstream effects this will have

Soil affects the climate and biodiversity and leads to often irreversible desertification (Figure 2).

Figure 2. (UN, Ecosystems and human well-being - Desertification synthesis).

Roots increase the stability of soil and prevent erosion (Gyssels & Poesen, 2003). In addition, trees provide cover and protect nearby fauna and flora. In areas prone to soil erosion, this is especially important as rainfall tends to be rare but when it does occur, it is often very intense and easily leads to topsoil being washed away. Roots are also important carbon sinks. Increasing root biomass is therefore very likely to improve the carbon budget of the plants we are seeding (Dr Alexandru Milcu, oral communication).

References:
Flagg, C. (1991) Acacia tortilis: Fodder tree for desert sands. The Forest, Farm, and Community Tree Network.
Safriel, U. et al. (2005) Dryland systems. In: Ecosystems and human well-being: Current state and trends. (Online) Available from: http://www.maweb.org/en/Condition.aspx (Accessed on 16 August 2011).
UNCCD (2011) Desertification: a visual synthesis. (Online) Available from: http://www.unccd.int/knowledge/docs/Desertification-EN.pdf (Accessed on 12 August, 2011).
Midgley, J. & Bond, W. (2001) A synthesis of the demography of African acacias. Journal of Tropical Ecology 17:871-886.
Gyssels, G. & Poesen, J. (2003) The importance of plant root characteristics in controlling concentrated flow erosion rates. Earth Surface Processes and Landforms 28:371-384.