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Dryland farmers are growing novel crops for biofuel, but domestication and research into yields and pests is still needed, says William Dar.

Whenever the world experiences prolonged high petroleum prices there is a search for alternatives, and in the last two years price rises have focused attention on biofuels.

Countries with biofuel programmes have strengthened their efforts, and many without have set one up. Using biofuels blended with diesel (up to 20 per cent) requires very little or no engine modifications. It also reduces un-burnt hydrocarbons by 30 per cent, carbon monoxide by 20 per cent, and particulate matter by 25 per cent. Moreover, sulphur content is negligible.

Biofuel crops for poor farmers

The International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), an international agricultural research institute that works to improve agricultural productivity in the drylands of Asia and sub-Saharan Africa, is focusing on helping poor dryland farmers join the biofuel revolution. Since the biofuel industry requires economies of scale, it usually bypasses smallholder farmers who cannot grow enough of the main biofuel crops. ICRISAT's pro-poor biofuel strategy links the poor farmer with the industry and the market by helping them grow appropriate crops.

For example, ICRISAT is providing sweet sorghum seeds to three groups of Indian farmers who traditionally cultivate regular sorghum, as sweet sorghum can be used to produce bioethanol. And in villages that have large tracts of wasteland, ICRISAT has been helping the poor and the landless grow jatropha, and sell the seeds to a company that produces biodiesel.

Jatropha plantations can be established in low-rainfall regions on wasteland and poor soils. Jatropha is easy to establish, quick growing and hardy, and is not browsed easily by cattle and goats. Its seeds contain up to 40 per cent oil. Although jatropha monocultures in block plantations are more susceptible to pest and diseases, intercropping can help. ICRISAT has evaluated sorghum, pearl millet, pigeonpea, chickpea, sunflower and safflower as intercrops. The yield from the food crop provides livelihood and economic sustainability, especially in the initial years before the jatropha crop matures fully and generates maximum income from biodiesel. But more research into pest control is still needed.

Good potential, but few facts

Certainly, despite the crop's potential, there is surprisingly little data on commercial yield levels per hectare, and no breeding programmes have been established. This could be a major unrealised opportunity for new research investment, and ICRISAT is working on this research.

Since jatropha is a highly cross-pollinated crop, each plant is genetically different. This offers great potential for selecting superior plants in a breeding programme. Domesticating another oilseed crop, jojoba, resulted in a 10-fold increase in seed yield and established profitable commercial plantations.

So far, we've seen large variations in the oil content of jatropha seed, ranging from 25 per cent to 40 per cent. We need to re-test this over time and in different locations to check whether the variation reflects genetic or merely environmental variability.

Studies also show individual jatropha plants can vary 18-fold in their average seed yield over four years. High-yielders were consistent over years, suggesting — but not conclusively demonstrating — genetic rather than environmental causes.

The National Biofuel Centre of the Petroleum Conservation Research Association, in India, estimates jatropha seed yields of 1.5 tonnes per hectare in wasteland plantations, which would translate into about 500kg per hectare of oil after extraction (540 litres). But the Centre of Excellence for Jatropha Biodiesel Promotion in Rajasthan, India, gives a much higher estimate for intensively managed plantations, of around 10 tons of seed yield per hectare or 3,400 litres of oil. Both forecast strong returns on investment after five years, once plantations have reached full maturity and give maximum seed yield. It appears that jatropha certainly has potential for good productivity.

Research priorities

Since estimates of jatropha yield show such huge variation, testing them is a priority. We need better definition of the crop's potential, so that accurate economic feasibility studies can be carried out.

We also need to improve propagation technologies, such as vegetative propagation and tissue culture, to enable rapid and efficient multiplication. Research to optimise field management practices for these novel crops is another priority.

Jatropha oil seed cake, a byproduct after extracting oil, is a rich source of plant nutrients, and its potential as an organic fertilizer should be further researched. It might also contain toxins with potential as organic pesticides. Similarly, research should explore whether the seed cake might also be used for energy production — for example as a feedstock in village-level biogas plants.

As the biofuel revolution continues, jatropha is being planted in large tracts across the world. Strengthening the scientific research in parallel will ensure that while the poor farmers reap the economic benefits, they are not exposed to unnecessary risk.

Dr William D Dar is director general of the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) and chair of the Committee on Science and Technology of the United Nations Convention to Combat Desertification (UNCCD).

This article is part of a Spotlight on The biofuels revolution.