Agriculture in Zambia no 3: Conservation farming and Jatropha cultivation
Post by Bert Witkamp
The cultivation of the Jatropha tree is propagated by the Conservation Farming Unit (CFU) of the Zambia National Farmers Union (ZNFU) in its conservation agriculture package. Below an account of my encounter with Jatropha (Jatropha curcas).
I should warn the reader that I am NOT a farmer FARMER. I rate myself a serious amateur. That does, however, put me on a par with the CFU target group when it comes to Jatropha. These farmers are generally small scale farmers using hoes and oxen in their cultivating efforts. Also for them Jatropha cultivation is an exotic adventure. Unlike the large majority of these farmers I do have access to the Internet and this gives me entry to info and knowledge they do not have.
The Jatropha originates from Central America. It exists in a number of varieties, the one we use is Jatropha curcas. It is a small tree growing up to six meter tall. Production of seeds starts in year 2 or three (if things work!) and can go on for some 50 years.
Notably GTZ (German Development Cooperation) has propagated the Jatropha, in a now abandoned programme located in Southern Province. A useful leaflet, however, remains titled The Jatropha System (accessible via The Net). Projects featuring Jatropha can also be found in India, where Jatropha cultivation is developing in a major way. An interesting site providing substantial technical information is www.svlele.com
In Southern Province a few farmers are experimentally growing Jatropha on a large, commercial scale.
|Two year old Jatropha trees planted as fence.|
What we did
We planted Jatropha during the 2008-9 and 2009-10 rainy season, hundreds of them as seed, seedlings and cuttings. We planted them closely spaced in places where we hoped and expected that they would develop into a living fence, and more widely spaced along one of the farm tracks. Our soil is shallow and sandy, located in agro-ecological region I.
The Jatropha tree is propagated as:
· It can be used to make a life fence.
· The seeds can be used as (1) source of oil for lamps (paraffin substitute), (2) commercially as raw material for bio diesel (this is at present only a future prospect and based on the anticipated increased expense of diesel), or (3) source of oil for soap.
· The seed cake can be used as organic fertiliser, as a source of biogas or, if detoxed, a source of animal feed.
· The tree is drought resistant and needs little water.
· Is supposed to be able to grow on “marginal” soils.
· Presumed medical properties.
Below Some Jatropha Things to Think About
Susceptible to disease
The Jatropha tree is an exotic tree, hence not naturally adjusted to local conditions including pests and diseases (that is, disease causing organisms). It is, for a layman, not possible to identify specific causes of disease. I do suspect that the tree is vulnerable to fungi, judging by diseased leaf (see photo) en also by plants dying because of some sort of “root rot.” I have applied fungicide occasionally but can’t tell how much good this did. This kind of problem is not mentioned in the Conservation Farming & Agriculture Handbook by the CFU. Combined with the idea that "Jatropha is easy to grow" one winds up in all kinds of speculations as to what causes your Jatropha not to grow so easily. Trace element lacking? Soil too shallow? Sick seed? Not enough water? Too much water?
|Jatropha with diseased leaf appearing as brownish spots, possibly fungus. |
Common at our place.
Water is needed
Jatropha water requirements for survival are low. The tree (apparently) is able to survive on only a litre a day. Nevertheless seedlings and young trees have to be watered/nurtured for several years through the dry season. You need to have the water, time and money to do this. My favourite system is to have the plant stand in the middle of a bowl shaped depression in which once every 2 weeks (but depending on size and time) the plant is thoroughly watered.
|Bottle water feeding a Jatropha seedling. |
Good for year 1 dry season. Fill once a week.
Propagation is by seed, either directly or by planting in plastic bag, or by cutting. Cuttings do not produce the tap root and might therefore do better than trees from seed on shallow soils on rock. The tree most commonly is propagated by seeds. We do not have special Jatropha grown seeds and seed quality therefore is erratic resulting in greatly varying up growing trees. At our land we have quite a number of minuscule trees, which despite being 2 years old, still look like seedlings. At the other extreme we have trees that are well branched and about 2 meters high.
Jatropha is supposed to survive on marginal land. This might lead one to underestimate the importance of soil preparation and continued care. Best is to prepare a hole of at least 25 x 25 x 50 cm by filling it with some rotted manure, topsoil or compost. This will do for seed, seedlings or cuttings. I also like to add some Zambian fertiliser formulation “C” (the one for roots & tubers which also has trace elements and organic material). Once or twice a year put some rotted manure in the plant basin and repeat the C type fertiliser. Fertilise when the plant starts to blossom and later during seed set. In the website mentioned above it says that one reason why Jatropha does well in India is because of applying cow dung as manure. In other words: even if you start out with poor soil you need to improve it, and the more so if you want to harvest the tree! Mulch as soon as possible if you have the organic material. Do not plant in periodically water logged soil or clay soils. Jatropha likes sandy and loamy soils.
We planted several hundreds of randomly collected seeds in relatively poor , shallow sandy soil. I estimate that about 1/3 of the seedlings died in the past 2 years because of various diseases and occasionally by insufficient water. The surviving trees show a great variety in development ranging from dwarf growth to healthy, vigorous vegetation. A few started to flower and produce seed in year 2. The impression that Jatropha is an easy plant to grow is wrong: you have to look after the soil it grows in and after the plant as well.
It would help if:
1. “Certified,” disease free seed would be available.
2. A leaflet (preferably also published as a web page) be produced describing how Jatropha is best cultivated. Including how to deal with its pests such as certain fungi and (organic) fertiliser schedules related to harvest and soils.
Post Scriptum in January 2014
At this point in time, 4 and 5 years after planting, we have roughly one third surviving trees, ranging in development from a few decimeters to some two meters high; from barely surviving to seeds producing. We don't have the water to go on watering them substantially during the dry season, they pretty much have to survive on their own. We do look after the bowl shaped basin, and once a year put in some compost and much.
Our previous conclusions have been confirmed in that:
- If you want to cultivate this tree to harvest this tree for it seeds you need to treat it as any crop - fertilise the soil, notably organically with manure or compost, keep it free from weeds and provide at least some water in the dry season. You also need good soil to start with.
- The tree does not thrive in marginal soil, and even its ability to survive in such soils is poor unless substantially aided by the cultivator/farmer though the provision of preferably organic fertiliser, water and care of the tree environment. Soil depth and possibility of developing a tap root are crucial factors.