This practice of planting in small shallow holes dug during the dry season and filled with crop residue or manure was first developed in Mali and was later adopted and improved in northern Burkina Faso by farmers after the drought of the 1980’s. This method has been successful in producing crop yield in places where soils have been so degraded that water can no longer infiltrate and topsoil has been washed or blown away. With time, zai holes have been proven to restore organic content and productivity to soil. Termites play an important role in this process through which unproductive hardpan is turned into living, productive agricultural land. The manure attracts termites that then tunnel beneath the zai hole, this facilitates increased water infiltration. The termites also provide another benefit; they assist in the decomposition of organic material added to the hole, making nutrients more readily available for the growing crops.
Zai pits catch water in places where rainfall is limited. Nutrients are concentrated and protected from high winds that threaten to blow away soils on the ground’s surface. The simplicity of this technology allows it to be implemented with minimal resources. As a strategy for responding to climate change, farmers in parts of the Sahel are increasingly employing zai hole farming method to improve or restore agricultural productivity to degraded farmland.
Limitations of zai crop production are important to consider, not all areas with limited rainfall and degraded soil also have “composting termites”. Zai holes can be used in areas without these termites but productivity and infiltration may be reduced. Digging holes is performed by hand, no technology has been designed to expedite this process, making it extremely labor intensive, 300-450 hours/ hectare. Digging in the dry season limits the time frame in which labor should be performed. Size and position of the pits is integral to their success, proper training is necessary to ensure productivity. Raw, organic material cannot be placed in pits, composted material is necessary for nutrients to become available to crops.
While this method is not a panacea for the famine ridden peoples of the Sahel, it is a positive and productive component of the evolving response to land degradation in that region. Other places around the world facing similar problems have begun to adapt zai holes to new conditions, these experiments will undoubtedly result varying degrees of success and new ideas about how to restore productivity to degraded soils and damaged ecosystems.
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