The Jatropha plant and its properties

Jatropha is an oil bearing plant, found throughout much of Mali. It is grown around crop fields and gardens to keep out animals, act as a windbreak, and to reduce soil erosion by wind and water. Jatropha hedges reduce the degradative effect of the wind and water, as soil collects at the bases of the hedges and these accumulations reduce erosion by surface runoff. It is very easy to grow, as a cutting taken from a plant, left to dry for 2 days, and simply pushed into the soil will take root. Jatropha needs only 400mm annual rainfall to grow, which means it can flourish even in Sahelian and semi-desert regions. Jatropha is very fast growing: plants grown from seed take 2 years to produce seed, those from cuttings take just 1 year. This means that jatropha can be an important weapon in the fight against desertification in the fragile Sahel environment.

A jatropha hedge in the rainy season (left); fresh seed on the bush is green, which ripens to yellow then black (centre); a green seed cut open to reveal the oil bearing nut inside (right).

Traditionally the seed has been harvested by women and used for medical treatments and local soap production. The oil which can be pressed from its seed is non-edible. However, this oil can be used as an alternative fuel for diesel engines, due to its similar chemical properties. This is especially important in Mali because of the use of small diesel engines in rural energy platforms to provide basic energy services to rural people.

A Jatropha energy platform, installed by MFC in the village of Tabakoro, southern Mali, uses Jatropha as an alternative to diesel fuel in the single cylinder engine at its heart (left); soil collects around roots of jatropha hedges and plants, decreasing surface run-off, improving water absorption into the soil and improving soil fertility (left & right).

The planting of jatropha as a living hedge has only positive environmental effects, as it protects the soil from wind erosion. The roots of the plant bind the topsoil, so it is less vulnerable to the wind (responsible for 30% of soil degradation). When planted in hedges, the wind blows soil to accumulate at the base of the plants, forming boundaries along the ground. This holds in water, allowing more absorption of water into the soil and consequently less loss of soil carried away by surface runoff. The roots of the plants also break up the earth which can become compacted during the dry season, causing high surface runoff when the rains come. This again allows more infiltration of water into the soil. The production of good quality fertiliser as a by-product of oil production will also act to improve soils and agricultural production (small scale gardening).

As jatropha is inedible even by animals (except when the plants are seedlings), the jatropha hedges will also protect gardens from damage due to animals, which accounts for between 5 & 10 % of losses of produce.

As jatropha can flourish in the Sahel climate, surviving on less than 400mm rainfall per year and resistant to drought and pests, it has the potential to contribute to the fight against desertification. The soil protection properties and ease of propagation mean it is well suited to being planted on land that has been lost through deforestation or desertification.

Jatropha has also many comparative advantages over diesel in terms of the environment. The most obvious is that using jatropha oil as a fuel creates a closed CO₂ cycle, i.e. when the oil is burned CO₂ is given out into the atmosphere. But when the next crop of jatropha grows, it takes the CO₂ back out of the atmosphere. Therefore there is no net release. With diesel combustion however, the CO₂ that was locked up inside the fuel millions of years ago is released, but there is no absorption. So the jatropha helps to reduce the climate change.