Scattered shrubs in pearl millet fields in semiarid Niger: effect on millet production.

Abstract

Various kinds of shrubs species are found in many fields and fallows in semiarid Niger. In order to understand the nature of their interactions with millet (Pennisetum glaucum L.) and their role in soil conservation, experiments were conducted in 1995 and 1996. Three treatments were applied with different shrub densities: cutting all shrubs, cutting half of the shrubs and leaving all shrubs. Millet was harvested per plot and in different circular zones around selected shrubs. In addition, transects across shrubs were investigated for soil parameters and microtopography changes. Millet yield and soil-nutrient status were higher around shrubs compared to the open field. Microtopography was elevated up to 20 cm near shrubs. The positive influence of shrubs on increased millet production extended to 2 m distance from the shrub. Competition between uncut shrubs and millet plants was found within a distance of 1.2 m. An increasing yield of millet was found in plots with shrubs up to a density of about 450 shrubs per hectare. Shrubs showed to be effective for preservation of soil fertility of fields in south-west Niger and thus important for millet production. Optimal for shrub management in farmers' fields would be cutting half of the shrubs and leaving the other half uncut for simultaneous wood production.