Today's image is coming from the Ethiopian highlands. In the valleys you can see thousands of small farms in a so called 'upland permanent farming' system. It is the final stage in the expanding usage of fallows, starting with the infamous slash & burn system. The natural fallow becomes scarcer when farmers are expanding the cultivated area and in the end, they end up in a system with a lot of small farms with almost no natural vegetation left. At the top of the hills, there is no cropland. These lands are the communal grazing grounds where herdsmen guide flocks of cattle and bring them back to their farms in the evening.
This intensive type of farming goes together with a list of environmental problems such as declining soil fertility and erosion. As there is no natural vegetation left, the soil does nog get the chance to recover. Why not? Trees regenerate nutrients through their deep roots. They use these nutrients to generate leafs, which will fall on the ground after some time. Microbial life and earthworms will decompose the dead leafs, putting the nutrients back in the soil. It's a closed cycle. The classic slash & burn system lets nature restore the soil before burning it down, leaving the big trees and concentrating the nutrients in form of ashes. After some years of cultivation, they let the forest grow again, restoring the old ecosystem and let the natural nutrients cycle restore the soil. Problem come up when the trees are removed definitely, as on our picture . There are no deep rooting systems anymore and trees are replaced by food crops. The leafs and other plant material won't fall on the ground and decompose but will be harvested. Instead of returning the nutrients back to the soil, they are removed from the field for human or cattle consumption. Due to the population pressure and the constant demand for food, farmers cannot let the forest restore as they need the land to produce crops. Year by year, they deplete the soil until there are almost no nutrients left in the soil.
Another problem is soil erosion. Due to the low nutrient content in the soils, there are not much plants covering the soil and as a consequence, raindrops have a strong impact during a shower. The energy of the raindrops loosen grains and wash parts of the soil away. This results in downstream mudstreams, even lower soil fertility as most of the nutrients are stored in the topsoil and even gullies can develop. To prevent this, farmers try to keep some trees and this is easily visible on the picture. The green branches are trees and bushes, located around local streams to prevent the banks for collapsing.
It all looks like a doom & gloom scenario but there are some ways out. The most viable solution might be the implementation of mineral fertilizers which replace the role of the natural forest to supply nutrients to the soil. However, mineral fertilizer do require farmers with some financial capital and a wel developed local market to sell the fertilizers. Increasing the livelihood of Ethiopian farmers may be reached by supporting such a local market and enabling the local community to acquire such mineral fertilizers, both in terms of logistics as in building a financial capital to buy them. To complicate everything even more, there is also the cultural aspect. Most of the farmer families are part of this agricultural system for ages and may be very critical to such drastic changes. Moreover, mineral fertilizers are not the only possible solution and they won't solve the entire problem. There is still a long way to go but the key message is that developing start with fully understanding all the aspects of a local system, both in terms of economy and culture as in in geography and agriculture...
© Google Earth/ Copernicus
(source information: course 'Agro-systems', teached by prof. Swennen at the KU Leuven, Belgium.)