suitable plants to combat erosion in Ethiopia

Hey,

I am going to be part of a project where we will apply different techniques to fight erosion in Arba Minch, Ethiopia. My task will be to collect information about suitable plant species to prevent erosion and also produce food at the same time. Can anyone recommend any source of information about useful selections of species in this set up or can share some advice? Thank you!

Tell us about the conditions there

I have never been to Africa and I have almost no information on that. I was told the soil is of volcanic origin and fertile. We will mainly plant on eroding slopes. About the climate: http://www.weatherbase.com/weather/weather.php3?s=105360&cityname=Arba-Minch-Southern-Nations-Ethiopia&units=metric

Do a Google search on vetiver grass. It has been widely used in the tropics to halt erosion and helps to restore fertility The roots also can reduce soil nematodes.It does not produce food directly, but can act as a nurse plant for establishing food-producing tree cover and mulch for gardens.

Beyond that, the ususal-suspect strategies of controlling /eliminating feral goats/camels, swale/gabion/earthworks, etc. would all come into play.

For a N-fixing tree species, the local yeheb nut (Cordeauxia edulis) is ideal. It is highly endangered due to overgrazing. The seeds are said to taste like cashews.

@Michael Martin: Thank you, that was very helpful! Yeheb is a perfect match! I looked for some trees/shrubs that would be good to battle erosion and produce a crop or provide animal fodder at the same time. Here's what I found:
Moringa oleifera
Moringa stenopetala
Sclerocarya birrea (Marula)
Ceratonia siliqua (Carob)
Cordeauxia edulis (Yeheb)
Parkia biglobosa (African Locust Bean)
Mesquite (Prosopis juliflora)
Senegalia senegal (Gum Arabic)
Acacia erubescens
Faidherbia albida (Msangu)
Uapaca kirkiana (Wild Loquat)
Cordeauxia edulis (Yeheb)
Inga edulis (Ice Cream Bean)
Cnidoscolus aconitifolius (Chaya)
Manihot esculenta (Cassava)
Brassica oleracea v acephala (Tree Collard)
Adansonia digitata (Baobab)
Dacryodes edulis (Bush Butter Tree)
Cajanus cajan (Pigeon Pea)
Cercis siliquastrum (Judas Tree)
Ficus sycomorus (Mulberry Fig)
Phoenix dactylifera (Date Palm)

If anyone could say something about the suitability of these trees for this particular scenario, it would be really helpful. Of course other suggestions are welcome, too. Nut trees and pioneer species in general would be especially great. To summarize the scenario:
Location: Arba Minch (Ethiopia), just outside of the city on eroding slopes, landslides already happening
Altitude: 1285 m
Average annual temperature: 21,8˚C
Average annual rainfall: 818 mm
Soil: very low carbon content, volcanic origin

I am glad someone already mentioned vetivert. It's the best erosion prevention plant, and builds soil 18 feet down. In addition, the roots are fragrant, and are the source of vetivert essential oil, a possible cash crop once the plants are established and the soil no longer washing away. With plenty of different plants available, my goats eat my vetivert, so it is animal fodder.

On to Moringa. The species I am familiar with is Moringa oleifera. It is also an excellent soil stabilizer, near impossible to kill, easy to propagate from cuttings. I think it may also be a nitrogen fixer host plant, but can't swear to it. Wikipedia has it in its own plant family, I thought it was a legume, based on leaf and seed pod, so who can say on that one. I looked for a photo of the root system but got frustrated.

Moringa is a super food. The seeds can be used to purify water, and I don't know what else. A session online would yield lots of information. It is good as animal fodder, and the leaves are good as a highly nutritious vegetable for humans. When my daughter was in the Peace Corps in West Africa they learned about its many uses, and how to propagate it, from seeds and as cuttings.

When I visited her, and stayed a month, I ate it cooked in a frittata, and it tasted like spinach to me. There were few leafy greens available, and that is an excellent one if you can have only one.

I don't recognize any of the other plants on your list, but at least these two grow anywhere hard to kill economically important plants are a great start.

good luck with your project.

Thekla

Legumes and a few others (Ceratonia, Parkia, mesquite, Acacia, Inga, and Cajanus on your list) are nitrogen-fixers and will enrich the soil around themselves, particularly if they are coppiced periodically as a chop and drop. Some produce useful food, and many produce fodder and fuel. A few other plants on your list (cassava and chaya come first to mind) are toxic or repellent in a raw state, but edible when cooked or otherwise processed. This is an important advantage in the Third World because such plants can resist the ubiquitous browsers such as goats which are everywhere and do so much damage unless very stoutly fenced and supervised.
Throughout the world, steep slopes when they must be farmed are stabilized by means of terraces. Vetiver and similar grasses, and "quick-set" shrubs which root readily from cuttings driven into the ground, when set densely on contour, are a quick way to start this process. Soil will build up behind the plants. But steep slopes are always best in permanent forest. If there is any kind of market economy, perhaps forest products, including fruit, wood, charcoal, etc. could be produced from the site, rather than homesteading on it?

Ah yes! The moringa can be coppiced, or pollarded if you want to keep some of the plant above the reach of the browsing goats. If they do eat the moringa to the ground, it will resrout. Goats won't totally destroy the or denude the countryside unless there are too many of them, and there is not enough food for them. In that case, eat the goats! They are prolific breeders, and when there is more fodder for them, then there could be more goats supported on the same piece of ground.

Moringa cuttings root readily in moist soil, and can be planted quite thickly. If you are in an arid situation, you would need to root the cuttings before planting them, and find a way to water them in the ground until they are established.

Hearing Alder's mention of terraces makes me think it is worth mentioning that your stabilization plants would do well planted along the contour of the slope, maybe several close set rows, then a space of a meter or more, depending on your future goals. The soil will build up behind / uphill from the rows of plants, decreasing the slope, and the beginning of a terrace. In that flatter area behind the original planting of, perhaps vetivert, you could plant another kind of plant that requires the less sloped site for its establishment.

Thekla

Thanks for the input so far!
About Moringa: I thought it was leguminous, too, but it's actually from the order of Brassicales, hence the name Horseradish Tree. This plant will probably be the most important one, due to its many uses, high protein content (up to 10 % in fresh leaves!!!), extreme growth rate (upt to 4 m per year) and drought tolerance. It also fixes nitrogen.
About the tree selection: A lot of the trees are nitrogen fixers, their main purpose is to fertilize whatever grows besides them to provide fodder for livestock and shade the ground. The plan is to integrate holistic grazing into the set-up.
About Vetiver Grass: I just looked at pictures, the root mass is pretty impressive. It's supposed to root 2-4 m deep, is drought-tolerant and survives heavy grazing pressure. That should be a very good ground cover around the trees to feed the livestock.

Do you know of any crops that can be grown under grazing pressure besides the trees? Chaya and Cassava were mentioned as they are toxic in raw state. What about Taro, Yams, Ensete or Bananas? I can probably forget about Sweet Potatoes, their leaves won't last long with goats browsing the area.

We have a tree nursery going to grow the trees we need from seed. So far there are only Moringa oleifera and stenopetala. How big does a tree have to be to not be killed by the goats (or cattle) when transplanted? Or is additional protection of the trunk needed in any case?

A quick note about how big the trees need to be before grazing will not kill them:

The plants have to be "established". The roots need to be doing their job in the soil. And the soil food web needs to be integrated with the roots. When you first transplant, their roots are not holding on, and they would be pulled right up. You tend them and care for them and they begin to actively grow.

The first year, you would want most, if not all the plants' productivity to go into making bigger plants, and a more extensive soil food community underground. Being from a temperate climate I think in terms of growing seasons. I don't know how this translates to wet/dry or year long growth, but I don't even expect to get much grazing during the second season.

You also have to consider what else there is for the animals to eat. And you need to see that the plants have the means to regenerate themselves. So, if animals eat one third of the above ground parts, that's not too hard to regenerate from because the plant still has the majority of its photosynthetic surface, and so can regenerate quickly (given water and sunlight).

Thekla

Hello John,
How is your project going? I'm interested in something a bit similar in Dire Dawa? Who are you working with? How has it been? What results and learning can you share?
Good luck,
Benjamin

Hello Benjamin,

the project is going great, you can check its progress here: slopefarming.org

John