When it rains, the muddy runoff builds up behind the cordons. Over time they grow to form effective and rapidly vegetating catchment barriers, reducing erosion and helping rainwater to infiltrate into the soil.
Moussa Konate has a secret. His fields of sorghum, millet and cotton are verdant and productive. Some neighbours are puzzled: they find it hard to believe he does not apply mineral fertilisers and other agro-chemicals.
"We have to feed the earth, so that it gives us what we need", says the farmer of Niamana, a village in southern Mali.
The humid heat of the rainy season makes everyone sweat. Attracted by some of the already mature sorghum grains, a few little red and yellow birds sing nearby. If one of the children throws a stone to scare them away, they escape and hide in the nearest trees.
Moussa uses his hand-made hoe to pluck weeds from his fields, adding them to the compost pile, under the big Baobab and next to the water well. That is where he works on his secret.
"I realized only good compost gives back the land what we take from it in a lasting way, and that is why I started producing it in great amounts."
Moussa has learned how to produce good quality compost with the Malian organic cotton association, who came to the region five years ago.
Ever since, he has strictly followed the recommendations: to gather organic materials from his fields and kitchen waste, mix the available animal manure, weeds and crop residues and place the materials in layers, watering the pile in the dry season and turning it every two weeks for optimal decomposition. The result is a rich and crumbly black earth ready to nourish his nutrient hungry soils.
He participates in the Syprobio project (see below), which investigates in a participatory way this and other innovations with small-scale farmers, who represent between 70% and 80% of the local population.
Altogether, 100 farmers from Mali, Burkina Faso and Benin participate in this large on-field research, some focusing on how to increase their most precious asset: soil fertility.
Bringing science and farming together
In Moussa's trial, he carefully quantifies and compares the advantages of applying good quality compost, comparing with the traditional habit of spreading undecomposed organic matter in the fields. The results confirm the expectation:
"The cotton parcel where the quality compost was applied has much taller plants and more cotton buds when compared to the parcel where undecomposed organic waste was applied, as we used to do."
Moussa stopped using the mineral fertilisers before learning how to produce the good compost: "The chemical fertilisers only help the crops in the first year, while the effect of compost can be felt up to three or four years after applying it."
And compost represents a more durable investment, he emphasises. "Besides, if it rains after applying mineral fertilisers, they will be washed by the water, whereas compost absorbs water instead of being carried by it, further helping the crops."
The other obvious advantage is the economic cost: making compost does mean work - but it costs no money, something of huge importance in a cash-poor society.
'Our food comes from the land we walk on'
Farmers like Moussa know they cannot afford to ignore the quality and fertility of the soil underneath their feet: "It does not matter if you live in the countryside or in the city, we cannot forget that everything we eat comes from the land we walk on. The way we treat it will determine our future."
According to the United Nations Food and Agriculture Organisation (FAO), soil degradation and soil fertility loss in Africa have risen in the last few decades. This trend is above all related to decades of inappropriate farming practices, deforestation, desertification, overgrazing and intensive soil erosion.
Over the last 30 years, food production in the continent remained more or less stable, despite a significant rise in cultivated surface. During the same period, however, the continent's population has more than doubled.
To feed a growing population by increasing food production in a sustainable way will probably be Africa's greatest challenge during this century.
'Holding' the good earth
Besides returning nutrients to the soil, as Moussa and other farmers are already doing, it is also important to keep the fertile top layers of soil from disappearing.
After decades of deforestation and aggressive agricultural techniques, soils are exposed to erosion. If vegetation is removed and fields are ploughed, torrential rainfall will have a clear road to carry away the top layers of the earth - where soil fertility concentrates.
To prevent water from washing away their livelihood, many farmers in the region started building 'cordons pierreux', or stone lines. The technique is simple: stones of different sizes are piled in long lines along contours on hillsides subject to rapid water runoff and erosion.
Then when it rains, the muddy runoff builds up behind the cordons. Over time they grow to form effective and rapidly vegetating catchment barriers, reducing erosion and helping rainwater to infiltrate into the soil.
Oh rose thou art sick ...
The links between soil fertility and food security can at times be less obvious. A poorer soil is a headache for farmers, not only due to weaker yields, but also because of an otherwise harmless looking plant: a little pink flower called striga.
Despite its beauty, striga is a feared parasite which stifles cereals, especially sorghum. The unusual feature of striga is that it likes poor soils, therefore having become even more infestive in the nutrient poor soils of Western Africa.
Koro Diarra, from the small village of Kombre, in southern Mali, is one of the farmers who declared war on the little pink flower. Her strategy is to increase her field's fertility by applying compost, which has the double advantage of controlling striga and nourishing her crops, increasing yields.
"Sorghum is the base of our diet, it's very important to us, and that's why we cannot ignore striga", says Koro.
In Moussa's fields, striga is already rare, as the soil has become too rich for it to thrive. The farmer is seen by local technicians and other farmers as a model producer. "I invested a lot of effort in compost production. With the good results, I was motivated to increase the amount", he says.
Other farmers visit his field to learn from him. "Some neighbours come to see my fields and understand that the effort of producing compost is worth it. After all, it is the ground that feeds us".
Fernando Naves Sousa is a conservation biologist and researcher at FiBL - The Organic Farming Research Institute, in Switzerland. He also contributes to different magazines as a freelance journalist.
Syprobio - Systèmes de Production Biologiques - is a participatory action-research program developed by FiBL (Organic Farming Research Center) in partnership with farmer associations and research institutions in Mali, Burkina Faso, and Benin, representing a total of 10,000 farmers.
The project is financed by EuropeAid and has a period of 5 years, having started in 2011. Syprobio aims to empower local farmers in the process of investigating and developing organic farming innovations which can promote food security and sovereignty, as well as a better farm income, particularly through the improvement of soil fertility, pest management and adaptation to climate change.