Dr. Bationo's work on soil fertility in Africa is usually worth reading, and this short book is no exception. Ten chapters summarise the major findings from long-term experiments conducted throughout Africa, although in this case ‘long-term’ means anything over five years because of the paucity of sustained experiments on the continent. There are chapters on effects of crop rotation, tillage, alley cropping and cropping systems (including economic and agronomic evaluation), as well as separate accounts of longer term experiments in the sub-humid highlands of Kenya (Kabete), semi-arid Kenya (Machang'a) and semi-arid Niger. The various authors claim that long-term experiments are an important source of evidence for soil fertility decline, and that they provide critical datasets for the development of sustainable management practices; it is unfortunate then that so few experiments last as long as 10 years because of a lack of funding. So what lessons have been learned? The first chapter, which reviews experiments from West, East and Southern Africa, contains the answers. There are six key points but, in short, the message is that the yield decline was common in all experiments even with inputs, but that the best results (in terms of both absolute yields and sustaining yields) were obtained from treatments that combined both inorganic and organic inputs. With such an apparently clear-cut result, is there a need to spend scarce resources on further long-term experiments, or should the money go instead into promulgating these findings and experience? On this the book is silent.
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