Population pressure and soil quality in Sub-Saharan Africa: Panel evidence from Kenya

Population pressure on farmlands can have two opposing effects on soil quality. It can negatively affect soil quality due to more frequent and intensive use of farmlands, but also can induce transition of farming methods towards more intensive farming in which more fertilizer and improved seeds are used in order to make smaller farmlands more productive. In Sub-Saharan Africa, the net effect is likely to be negative given the region’s current low fertilizer use. Recent studies, however, show evidence of agricultural intensification in regions with high population pressure. It is important to analyze the extent and speed of soil degradation and its relationship with population pressure. Nonetheless, empirical studies on this topic are almost non-existent, partly because soil quality is shaped over a long time horizon, and quality panel data on this issue are rare. We use unique panel data for rural households containing soil quality information from Kenya to elucidate the effect of population pressure on soil quality. We find that population pressure reduces soil quality and also induces agricultural intensification. This suggests that although farmers are trying to mitigate the negative effect of population pressure on soil quality, the rate of soil degradation is outpacing that of intensification.