K.B. Adeoye¹, O.A. Folorunso² and M.A. Mohamed Saleem³
1. Department of Soil Science, Ahmadu Bello University, Zaria, Nigeria2. Department of Soil Science, University of Maiduguri, Maiduguri, Nigeria
3. International Livestock Centre for Africa (ILCA), Subhumid Programme, Kaduna, Nigeria
The physical properties of Vertisols from the Lake Chad Basin of Nigeria depend on the nature of the predominant cations in the exchange complex. The percentage of water-stable aggregates and the hydraulic conductivity are drastically reduced by Na and to a lesser extent by K, whereas Ca and Mg increase these two properties. Addition of phosphogypsum has no significant effect on water retention, plasticity and aggregate stability, but it decreases the degree of dispersion and effectively prevents a sharp decline in the hydraulic conductivity compared with the control.
Some implications for land use, long-term irrigation and reclamation of these Vertisols are discussed. The potential for large-scale sustained grain production under extensive irrigation in the area appears to be very high because good quality water is available from Lake Chad and boreholes. Increased availability of crop residues to be used as feed will enhance the integration of livestock and arable crops in farming this area. Poor drainage is currently constraining the agricultural productivity of these soils. Physical surface drainage and the addition of gypsum can alleviate this constraint.
