Waterlogged Soils: a Plow to Increase Productivity

Five years ago a multidisciplinary research and development team from the International Livestock Center for Africa (ILCA), two other international organizations, and five Ethiopian agencies, set out to prove that the food-producing capacity of Africa's Vertisols could be substantially increased.

Working in the Ethiopian highlands, the Vertisol Management Project developed an animal-drawn plow and refined cropping methods that considerably increase crop yields. Faba bean yields can increase as much as 330% and wheat 130% above the average; yields of straw and other crop residues rise proportionately.

The technology that has been developed is applicable to soils that have drainage problems caused by low evapotranspiration and infiltration. This includes vast areas of sub-Saharan Africa, as well as other semi-arid areas of the world where Vertisols predominate or which have these problems.

Background

Vertisols are deep-cracking, black clay soils characterized by severe waterlogging. In many highland Vertisol areas farmers avoid much of the waterlogging problem by planting late, toward the end of the rainy season. But using only part of the growing period leads to low crop yield and considerable erosion because fields are without vegetative cover for much of the time.

Currently, large areas of Africa (as well as other Vertisol regions of the world) are not cropped, due to waterlogging. Farmers of Vertisols have long known that drainage problems must be overcome. Land cultivation in the Ethiopian highlands-as in many African countries-relies on animal power. However, the indigenous, animal-drawn plow has little land-shaping capability to make drainage structures. Therefore, farmers plant on a flat bed or make ridges and plant on top of them. Others scoop the soil by hand to make broad beds to plant on. The mounding task, commonly done by women and children, is back-breaking and must be repeated each year.

Vertisol Technology

The key to unlocking the productive potential of these Vertisol areas lies in the development of an effective, low-cost, animal-drawn plow that would increase drainage, and do it more efficiently than traditional methods.

Thus, ILCA and the Center's collaborators developed the broadbed maker (BBM). It is based on traditional Ethiopian implements-the "ard," or wooden-frame plow, to which is attached the "maresha," the metal plowshare with its land-shaping moldboard.

The new technology is merely an improvement on a very ancient system. And, since the basic technology (plowing with animals and use of the maresha) is already part of many farming systems, farmers regard it as culturally comfortable and adaptable.

The BBM uses two mareshas mounted about 120 cm apart on a crossmember. As it is pulled through the soil by a pair of animals, it makes two parallel cuts. The wings scoop the soil toward the middle and mound it. The result is a series of broad, raised beds 15 cm high, 80 cm wide, separated by 40-cm-wide furrows.

The potential effect of this tilling device on Vertisols and on their food-producing capacity is immense. The greater water evacuation as a result of using the plow allows for earlier planting. These "extra" growing days permit sowing of long-duration varieties; or two short-duration crops can be grown. Using high-yielding varieties that respond better to fertilizer can increase yield even more.

Potential benefits are long-lasting. Early planting helps establish a vegetative cover early in the rainy season, therefore, reducing soil erosion.

Use of the BBM and the accompanying land-management technology has wide application. Vertisols make up 3 percent of all African land area, covering about 85 million hectares in sub-Saharan Africa (13 million hectares in Ethiopia alone). There are millions of hectares worldwide where waterlogging is a problem, yet where plowing with animals is traditional. These areas are potential users of the technology.

Importance of Livestock

The most important contribution livestock can make to improved use of sub-Saharan Vertisols is their use as traction animals. Thus, crop-livestock interactions in the predominantly mixed and agropastoral farming systems could be strengthened for the benefit of both subsystems.

In addition, livestock contribute manure for plant nutrients, which in turn increases yields both of food for humans and of crop residues for animal feed. The potential to increase crop residues could have a tremendous impact on animal feed resources.

Implication of the Technology

Since Vertisols are widespread throughout the tropics, there are obvious possibilities for transferring Vertisol management experience from one area to another.

The Vertisol project is predominantly subsistence-oriented. The cost of the implements to convert the maresha to the BBM is US $20. Engineers have developed components made of wood to hold the implement together, materials readily obtained and fashioned. The technology saves labor-up to 40 percent over traditional mounding methods, allowing people to spend time on other tasks. Also, the mounds do not have to be re-formed each year if stubble from previous crops and weeds can be eliminated by other means.

Summary

The Vertisol technology developed by ILCA and its international and national program partners is:

  • leading to increased food crop and residue production to levels in line with the potential of these soils
  • improving the efficiency of animal power use
  • increasing the number of livestock through increased feed availability and improved management of crop residues The project also promotes task-sharing among institutions. An advisory committee composed of chief executives of all participating agencies oversees the project; a technical committee implements the activities.

    The Vertisol Management Project is a model of institutional and interdisciplinary collaboration, combining innovation and sustainability with demonstrated potential for readily exploiting some of the world's best, yet underused, land.

    Information in this article provided by Jack Reeves, ILCA.

     For more information:

    Jack Reeves
    ILCA, P.O. Box 5689
    Addis Ababa, Ethiopia
    (251-1)61 18 92