* Promoters say jatropha ideal for harsh climates
* Activists say grow food, not jatropha, on arable land
* Investor returns on biodiesel plant uncertain - industry
By Juliane von Reppert-Bismarck
BRUSSELS, Jan 21 (Reuters) - Jatropha, a biofuel-producing plant once touted as a wonder-crop, is turning out to be much less dependable than first thought, both environmentalists and industry players say.
Some biofuel producers found themselves agreeing with many of the criticisms detailed in a report launched by campaign group Friends of the Earth this week -- "Jatropha: money doesn&${esc.hash}39;t grow on trees".
Jatropha has been widely heralded as a wonder plant whose cultivation on non-arable land in Africa, Asia and Latin America would provide biodiesel and jobs in poor countries without using farmland needed to feed growing numbers of local people.
"The plant can withstand dry conditions, low nutrient levels and exposed conditions," according to the website of the Netherlands-based Jatropha Investment Fund. "Many desert areas and land which is not currently cultivated will be very suitable for the establishment of plantations."
But some biofuels producers have found the plant less robust than first thought.
"Jatropha is not the miracle crop that many people think it is," said Dominic Fava, business development manager of British biofuels firm D1 Oils <DOO.L>, which processes jatropha grown in Asia and Africa.
Other company managers say that while the plant needs no irrigation, high yields depend on good soil and chemical additives.
"The idea that jatropha can be grown on marginal land is a red herring," Harry Stourton, Business Development Director of UK-based Sun Biofuels, which cultivates jatropha in Mozambique and Tanzania, told Reuters.
"It does grow on marginal land, but if you use marginal land you&${esc.hash}39;ll get marginal yields," he said.
Sun Biofuels estimates its Mozambique plantation, once it matures in two years, may yield two tonnes of oil per hectare of jatropha, and notes it is grown with fertilizers and pesticides on the fertile land of former tobacco fields.
"It is perhaps inappropriate to be offering guaranteed returns at such a stage of domestication, when we&${esc.hash}39;ve still got a lot to learn about this crop," said Fava.
The report was launched amid a heated debate in the European Union about biofuels, which critics charge are competing for land with food crops and creating unwanted side-effects around the globe. [ID:nLDE6BK199]
"It&${esc.hash}39;s good that developers agree jatropha is no wonder-crop. But it means they&${esc.hash}39;ll grow on fertile land," said Christine Pohl, author of the report.
"We think such land should be used for food production, particularly in light of growing populations and in light of global food insecurity," she said. (Reporting by Juliane von Reppert-Bismarck; editing by Tim Pearce)
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