Trees for fuel and fertility
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CTA. 2008. Trees for fuel and fertility. Rural Radio Resource Pack 08/3. Wageningen, The Netherlands: CTA.
Permanent link to cite or share this item: https://hdl.handle.net/10568/57381
Planting nitrogen-rich trees that also provide fuelwood
Trees for fuel and fertility Cue: When we talk about renewable energy, we may think first of technologies like solar panels or hydroelectric dams. We probably don?t think of firewood, not least because much of the firewood we use is not from renewable sources; trees are felled but not replaced, and in time the land becomes deforested and barren. But given responsible harvesting and replanting, trees can be an excellent source of renewable energy. And for farmers, some tree species not only provide fuel, but also boost soil fertility, contributing energy that crops need to grow. Hellen Wangechi, who works for the Tropical Soil Biology and Fertility Institute in Nairobi, Kenya, works with farmers to promote tree planting. Visiting her on a windy day at her field station in Laikipia, Winnie Onyimbo learned more about how to make better use of trees on farms. IN: ?When advising farmers on tree ? OUT: ? and you can do very well.? DUR?N: 3?00? BACK ANNOUNCEMENT: Hellen Wangechi with some sensible advice for tree planters. The interview comes from a resource pack produced by CTA. Transcript Onyimbo When advising farmers on tree planting does a choice of tree vary between different locations? Wangechi Wow, yes it does and it varies with agro-ecological zones. When you look at the rainfall, for example, when you look at the soil, the soil type, it varies. Like the tree you will plant in Mombassa at the moment is not the same tree that will do well in Nyeri which is cold. So the tree varies with the region. So the farmer has to be advised. Onyimbo Are there trees that are good for both fuel and also for soil fertility? Wangechi Yes, like sesbania, it takes about 3-5 years, it is very good in nitrogen fixing and also good in fuel wood. We also have Cajanas cajan, that it is the pigeonpea. It also provides fuel wood and nitrogen, as well as food: the pods, we eat the pods. And quite a number of other trees, like tephrosia also provides both of them, among many other trees. Onyimbo Do you encourage farmers to plant one species or do you encourage them to plant a mixture of species? Wangechi Most of the time we tell them to mix the species because there is a bit of compatibility. Even when you look at maybe disease outbreaks and all that, if you have a mixture of trees there is a tendency that some trees will resist of course and some will die, some will remain. And also when you have a mixture of trees, also you know the products that you get from the trees, they vary also. You will be able to get maybe edible pods, fuel, timber, from a variety of them. So we advise them to plant as many varieties, as many types as you can on your farm. Onyimbo What are good practices for harvesting fuel wood? Wangechi Personally I would not encourage a farmer to cut a whole tree but I encourage people to prune the trees. Pruning removes the side branches and if you have enough trees on your farm you can be pruning trees every now and then and you get enough supply of fuel wood. Onyimbo Ok what are good practices for increasing soil fertility? Wangechi You can use trees. The nitrogen can be added into the soil when the leaves fall and they decompose. Or the same trees can be cut and they can be incorporated into the soil so they add nitrogen. But for other nutrients like phosphorus and potassium, there are some trees that have been found to mine. Mining is the sourcing of the nutrients from deep into the soil and it is recycled, brought up into the upper soil layers or the soil surface where the plants or the growing crops can take it up. Onyimbo Ok one last thing, what would you advise African small-scale farmers on planting trees, both for soil fertility and for fuel wood? Wangechi Seek for information first before you plant. Be advised by the experts on what to plant, where to plant and how to plant it, and the best type for your particular region because not all trees do well in that particular region and again not all trees supply the same amount of nitrogen. Seek information and it is there, we have institutions dealing with that and you can do very well. End of track
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