Pioneering the cultivation of Jatropha Curcas

The jatropha curcas, a genus of tree whose seeds contain a high quality, non-edible oil, is one of the most exciting new potential sources of renewable energy in the world today. While the tree has grown wild in Africa for many hundreds of years, it has never been grown on a commercial scale. One of the key pioneers of commercial jatropha production is British-based Sun Biofuels. Having successfully established their first plantations in Mozambique and Tanzania and now harvested their first seed, few organisations can claim a comparable level of knowledge and expertise in the cultivation of this remarkable tree. This paper outlines the company’s key findings:

Jatropha’s growth, flowering and fruiting features
Overall growth pattern:  Sun Biofuels’ trials in Mozambique confirm previous studies that in the right climatic conditions, early growth is fast and trees are able to bear some fruit within seven months of planting. Commercial levels of fruiting more generally occur during the subsequent season (one and a half years after planting). Jatropha trees reach maturity in four to five years and continue yielding fruit for 40 years or more.
Root system:  When grown from seed, the Jatropha plant sends down a tap root that develops into an extensive root system which can penetrate deep soils. This endows the plant with robust drought tolerance and the ability to thrive on land that is suboptimal for food crops.
Flowering:  The plant is ‘monoecious’, with male and female flowers on the same branches. Flowers are pollinated by insects, especially honey bees. Flowering occurs in the wet season and slightly beyond (typically from November to July in Mozambique and Tanzania).
Fruiting:  Fruit development takes place approximately 90 days after flowering. Flowering and fruiting occur on the same plant throughout the fruiting season which, in Mozambique and Tanzania, runs from February to October.

Plant Propagation at Sun Biofuels
Jatropha plants can be cultivated by two methods: ‘Generative’ propagation (where seeds are directly sown into the ground and ‘Vegetative propagation’ (the planting of cuttings taken from healthy plants or the transplanting of seedlings pre-cultivated in nurseries). The company’s trial plantings have confirmed that generative propagation is the most effective as it maximises root development. Jatropha propagation is carried out through direct sowing in north-south rows spaced 4m apart, with trees at 1.5m intervals on each row, maximising light penetration and optimising plant density.

Land preparation and planting processes
Land preparation:  Land is cleared of all brush and vegetation. The soil is then worked by ploughing (and deep ripping if heavily compacted) to offer the best possible conditions for seed germination and root penetration.
Planting:  Seeds are planted on weed-free soil at the start of the rainy season. Natural precipitation provides sufficient moisture for germination, usually taking 10 days. SBF’s trials and commercial planting have been highly successful, achieving germination rates over 95 per cent.

Maintenance Activities
Weeding:  While Jatropha can survive competition from weeds, growth and productivity is maximised through weed control during the first and second years after planting.  At SBF’s plantations, manual ‘ring-weeding’ is carried out around the base of young plants.
Pruning:  Careful cutting back of selected shoots and branches increases crop productivity by stimulating growth, maximising light interception and encouraging optimum branching for flowering and fruit development.
Disease Control:  To maximise plant growth and yield, pesticides, fungicides and herbicides can be selectively applied as and when needed, both manually and mechanically in conjunction with a programme of integrated pest management (IPM).

Harvesting
Harvesting period: Fruit is harvested on reaching maturity (when it turns from green to yellow) typically 90 days after flowering. At this point the oil content and quality is at its highest. Because the same plant continually flowers and fruits throughout the peak season (April to October), harvesting takes place over most of the fruiting season, representing a six to seven month harvesting ‘window’.

Harvesting Methodology
Manual harvesting:  At present, harvesting is a relatively labour intensive process, comparable to the oil palm, coffee and cotton industries. Picking efficiency on a well managed plantation is anticipated to be at a rate of 150kg/day per picker, based on the latest production methods and studies. Selective mechanical harvesting equipment for jatropha is currently under trial and development.

Industrial-scale jatropha production is still a nascent industry requiring the continuous innovation and refinement of cultivation techniques. Sun Biofuels are therefore committed to an ongoing programme of investment in research and development to continually optimise both seed and oil yields.