In Fansirakoro, a small town in the Upper Niger River Valley of Mali, a local farmer asks University of Hawaii researcher Richard Kablan to come and see something behind his house. The rains in Fansirakoro fall sporadically and water scarcity is a real concern. Until recently, residents even became nomadic for a few months of the year when local wells ran dry.
Walking to the back of the house, the farmer shows Kablan not only a field full of crops, but also two oxen and a plow – items he was able to recently purchase for the first time in his life.
Many years earlier in 1997, the USAID Soil Management Collaborative Research Support Program (SM-CRSP) introduced a new soil management technique to the area called
amenagement en courbes de niveau (ACN), which translates roughly as ‘ridge tillage.’ Working in close collaboration with Mali’s Institut d’Economie Rurale and the University of Hawaii, SM-CRSP worked across the region to improve food security through better agricultural practices.
According to Russell Yost, the principal investigator under SMCRSP, “The soils [in this region] have a very low infiltration rate – they crust – and when the rain falls, it largely runs off … We found that upward of 60 percent - sometimes as high as 80 percent or 90 percent - of the rain actually turned into runoff and did not infiltrate the soil.” For local farming families, this has meant poor crop yields and periodic water shortages.
The ridge tillage technique was originally developed in Mali by the Agricultural Research for Development Center (CIRAD). Working in conjunction with Dr. Mamadou Doumbia and his team at the Institut d’Economie Rural, CIRAD began testing ACN in the Malian town of Siguidolo in 1994. USAID picked up this work in 1997, and according to Dr. Doumbia, helped make ACN what it is today.
When USAID staff traveled to Siguidolo to see ACN for the first time, “… frankly, we were blown away with its wonderful success,” said Mr. Yost. To put this in perspective, he explained that Siguidolo has very little rainfall – even less than Fansirakoro – yet with ACN, Siguidolo’s residents were able to grow crops with high water requirements, like corn.
The ridge tillage process begins with a relatively low-tech topographic survey of a farmer’s land to identify water flow problems. Working closely with soil and water conservation technicians, the farmer next determines the ideal locations for ados, or ‘earthen ridges’ that parallel topographic contour lines. The farmer then uses an ox-drawn plough to construct the ados, which will remain in place for years to come.
This relatively simple intervention has had wide-ranging impacts on food security and ecosystem health, and supporters hail it as one of the most successful soil management techniques to combat the low infiltration rates of West African soils.ACN dramatically increases infiltration, boosting crop yields by 30 percent. By reducing surface run-off and soil erosion, the technique also helps soils retain important organic nutrients and fertilizers that would otherwise wash away.
According to research conducted under SM-CSRP, farmers that combine ACN with fertilizer application have seen crop yield increases of around 50 percent.
“This is not the kind of technology where you have to wait for several years to see something happen. The minute you put it in the ground, you see the crops respond,” said Richard Kablan.
According to USAID’s contracting officer’s technical representative for the project, Michael McGahuey, the impact on farmers’ bottom line is significant: “Based on the documented yield increase of 30-50 percent, it is estimated that the value of the annual yield increase ranges from $40 to over $50 per hectare.” The benefits of ridge tillage do not stop there, however.
Dr. Doumbia noted, “Two years after putting the technology in place in Siguidolo, the farmers called us and asked us to come back. They told us that they’d noticed young trees growing, and that they hadn’t seen anything like them for the past 15 years.”
Curious to understand this resurgence of local plant biodiversity, Dr. Doumbia and his team began taking measurements. They soon realized that ACN enables rainwater to penetrate well below the crop-growing zone, reaching depths down to two meters. In this way, ACN was helping fuel the regeneration of indigenous plants and commercially important perennial trees such as V. paradoxa, the shea butter tree whose oil is collected and sold by local women.
ACN also facilitates carbon sequestration by boosting plant biomass. Though it remains challenging to quantify this impact, there may come a day when Malian farmers could receive credit in international carbon markets for improving local soil management practices.
Back in Siguidolo, a rising water table also enabled local women to start home gardens. Richard Kablan recalls that one woman, Sorofin Diarra, was so keen to take advantage of the improved growing conditions that she started her own home garden in the middle of one of SM-CRSP’s test plots. Today, as a direct result of ridge tillage, about 80% of all households in Siguidolo have such gardens, growing crops like lettuce, tomatoes, and onions. These gardens continue to provide crops well into the dry or ‘hungry’ season, which can last up to eight months in the arid Sahel.
Years into the project, “impacts kept popping up,” recalls Dr. Doumbia. The farmers soon called CRSP researchers once again, this time to report that their wells still had water, despite the fact that the dry season was well underway. He and his team soon confirmed that ridge tillage facilitated even deeper infiltration, helping recharge the groundwater aquifers that feed local wells.
On a regional scale, there is evidence that drier conditions are moving southward from the Sahara and down into the Sahel. With less reliable rainfall and increased water scarcity, ACN has a clear role to play in helping families better prepare for the effects of climate change. After introducing the technology to Fansirakoro, Siguidolo, and elsewhere in Mali, USAID-CRSP took the technology to Gambia and Senegal where the results were similarly impressive.
Today, L’Association Malienne d’Eveil au Développement Durable, the local NGO in Mali that provides technical assistance to farmers during the initial diagnostic, is having trouble keeping pace with demand. Part of the challenge is obtaining the funds needed tosupport roll-out of the technology, as SM-CRSP came to an end in 2008. Though ACN work does continue under a sister USAID Project (SANREM-CRSP), people affiliated with SMCRSP wonder if the scale is large enough.
“We have a strong case, as we can show impacts,” Dr. Doumbia stated. “And the impact keeps building and building and building. If somebody wants to show impacts quickly – I mean quickly – then invest in ACN. Today, ACN has been extended to thousands of hectares [in Mali]. Imagine where would we be if we could bring 1 or 2 million hectares under ACN…The potential is so great.”
L.K. ole-MoiYoi
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