At least in the semi-arid regions of Africa, if within-field soil variability is not takeninto account, efforts to increase soil fertility will be less efficient and less likely tobe adopted by farmers. Most of these farmers already practice =precisionagriculture‘ and take short distance variability into consideration in theirmanagement. One can safely assume that they do so for good reason, given thattheir management systems have developed over many centuries.Precision agriculture is also relevant for the introduction of modern technologies.For example, the same principles are relevant to the efficient application ofmanure and the efficient application of compost and mineral fertiliser.For the best solutions, farmer knowledge, extensionist knowledge and researcherknowledge of within-field soil variability need to be combined.