Evaluation of the effects of some agroforestry practices on selected properties of soils in a sub-humid zone of Ghana

Abstract

The study investigated the effects of three 5-year-old cropping systems comprising Leucaena hedgerows with cowpea (Vigna unguiculata), maize (Zea mays L.), and groundnut (Arachis hypogaea) on the accumulation of soil organic carbon, bulk density, porosity, and aggregate stability; and compared these with soils under a Leucaena woodlot of similar age in a forest-savanna transition zone of Ghana. The woodlot soils had the highest accumulation of organic carbon and total porosity. The aggregate stability in this system was more than twice the values for the alley cropping systems. Furthermore, the aggregate stability correlated well with the soil organic matter (r = 0.77**), suggesting that it can be well estimated from organic matter content. Among the three alley cropping systems, the accumulation of organic carbon was in the order cowpea> maize > groundnut, but the aggregate stability did not show any consistent pattern with organic matter content in these systems. The results indicated that despite the periodic addition of organic matter from pruned Leucaena hedgerows to the soil, the alley system did not improve the aggregate stability as much as the woodlot system. Ghana Jnl agric Sci. Vol.32(2) 1999: 153-158