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Is jatropha really the 'miracle' biofuel crop that some profess it to be?

Following on from my posting regarding the Roundtable on Sustainable Biofuels Consultation – Europe stakeholder outreach meeting (Brussels, 19th March 2009); I would like to summarise some of the comments I noted during the meeting regarding Jatropha curcas production in Africa. These comments have led me to question the favourable claims made about this crop.

- Allelopathic effect are apparent, preventing other crops being grown on the same ground after jatropha. This is contrast to some reports that suggest jatropha improves soils by decreasing their pH and increasing organic matter.
- Poor yield on poor soil. To get a worthwhile yield, the plant needs to be fertilised (hence decreases any GHG off-setting). This is in contrast to reports that suggest the crop will yield well even on poor marginal land.
- Jatropha produces inconsistent yields from plant to plant grown under the same conditions, due to the genetic diversity of the species. Jatropha, as a relatively new domesticated crop, has been little improved from its ‘wild parents’.
- The seeds do not mature at the same time making mechanical harvesting difficult. Jatropha has until recently been harvested by hand (often by children = cheap labour), where multiple harvests in one season is less of an issue.
- Jatropha is poisonous; therefore the seed proteins cannot be used as animal feed reducing its value as a biofuels oil crop.
- Jatropha has recently been banned in South Africa because of its invasive potential.

What are the experiences of others?

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I am a bit skeptical with your comments because I do not believe in all totality that Jatropha may not be the crop for biofuels production. I am currently undergoing a research and development on the performance of jatropha when intercropped with some other crops, the results inconclusive yet is interesting and encouraging.
However, i must say that propagating Jatropha with seeds have been very difficult infact I had to do that several times this had been corroborated by some researchers. What baffles me is that seeds from the same crop, harvested same time do not germinate evenly despite the same conditions. I am convinced that despite the shortcomings this crop will still solve to an extent global climate change
You could try looking for research information on the Biofuels Abstracts database. You have free access to the database on this site. For instance, there are a number of papers on jatropha seed germination, intercropping and allelopathy. Sign in, click on Abstracts on the toolbar, and try the following searches:

jatropha and seed germination
jatropha and intercrop*
jatropha and allelopathy

This information might help with your research.
I came across the web site Biofuels Information, produced by the Bureau of Agricultural Research, Government of Philippines, www.bar.gov.uk.ph/biofuelsinfo. On this site there is a downloadable document - a Primer for Jatropha http://www.bar.gov.ph/biofuelsinfo/downloads/PrimerJatropha.pdf
The primer does cover some of the problems you identify Carol, but there doesn't seem to be any mention of invasiveness. Looking at the researchable areas though its looks like Jatropha is not one of the key targets in Philippines.
About the first comment: the allelopathy is only after the crop and not when the jatropha crop is on?, I could have seen many pictures showing the intercropping with some cucurbitacea; in our plantation the volunteer-onions that remain after the previous crop have a good performance, and we have had to do three hand-hoe weedings and other three herbicide treatment on just one-hundred days.
Research Christian Aid has supported in Africa supports many of your points and indicates that jatropha is not really about marginal land at all...

http://www.christianaid.org.uk/pressoffice/pressreleases/August2009...
Almost all biodiversity for jatropha is in Mexico and guatemala. The varieties in Africa and westwards are almost all the same. So far it shows little sign of invasiveness in Kenya. We have had mature trees around for years. Vincent Volckaert of DI oils has been doing intensive hybridisation and reckons to have a reliable seed ready by next year, quick maturing and high yielding. It will probably still need adequate warmth, its preferred long intial rainy season ( 5 months)and stably warm day night termperature variations. We have it growing very at 2000 metres on the equator in one trial site, small seed low yield with low oil content but then the soil was very acid and low in nutrients... but the attitude of one agronomist was if it grows, we can fix the rest. Time will tell.. Croton Megalocarpus may be more useful in more ways than one at that altitude, the challenge being the long initial fruiting time of 5- 7 years.
Best
Sue

We do have some invasive species in Kenya and with forest cover down to 1.7% mainly due to woood biomass use and charcoal.. a reasonable question could be whose space will an even slighly invasive jatropha take?.

Carol,

I am a latecomer to this blog, however i would like to answer some of your points one by one:

1. Allelopathy: We have tried various intercrops with Jatropha with economic yield. Even after harvest of Jatropha if the soil is well ploughed these effects do not appear, as is the case tried by us. However, if mild effects exists , it vanishes in a few weeks.

2. I agree with you here. Because on marginal soils without inputs these crops can grow but not yield economically. Also note that water also is an equally important input.

3. It is observed that if the plants are propogated by seeds such differences are observed. However, if they are vegetatively propogated these differences minimises. The only other way is development of good plant types, which i think most of the reserach institutions are into.

4. Again this is a factor due to the varietal influence and can be solved only after release of a consistent and high yielding variety, which will take some more time as per the public info

5. Jatropha is poisonous and cannot be used as feed.

6. The invasive potential of Jatropha cannot be agreed to as hundred's of researchers are working on the field and have found no such property of the plant.

Hi Carol,I would like to emphasize some of your points of view:

Poor yield on poor soil is evident,based on our reseachs about the suitability of the plant throught out the country,It has been observed to grow and develop well on fertile and watered soils while development and growth on acidic and infertile soil of the western province of the country(Rwanda) is very week, diseases and insects'attack are more frequent,thus jatropha need to be fertilized   and management practices respected. The crop do not thrive on marginal soils

It is a good coohabitant to traditional food crops like maize,as it has been observed on our field trial,maize has not encountered any problem in grow and even  yields the same as those from maize grown alone.

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