Chloride Movement in Forest Soils of Nigeria
1986
Ghuman, B. S. | Lal, R.
Chloride movement studies were conducted with forest soils at six locations in Nigeria: Ibadan, Ikenne, Ikom, Mokwa, Onne, and Zaria. The soils at Ibadan, Ikenne, Zaria, and Mokwa are classified as Alfisols, those at Ikom and Onne are Ultisols. Potassium chloride was uniformly broadcast on the surface of 145- by 145-cm plots and displaced with 8, 4, 4, and 4 cm of water applied as flood irrigation, keeping a 1- to 2-cm head at the soil surface, at 1-d intervals. No evaporation was allowed during soil-water and solute redistribution. Immediately after infiltration of each incremental application of water, duplicate solution samples were obtained using solution samplers installed at 10-, 20-, 30-, 50-, 70-, and 90-cm depths. After infiltration of the first water increment (8 cm) much of Cl⁻ moved beyond the 90-cm depth in the Ikom soil, a well-structured clayey soil. Chloride concentration peaked at 70-, 10-, 30-, and 20-cm depths in the Ibadan (gravelly soil), Ikenne, Mokwa, and Onne (leached soil) soils, respectively. There were two Cl⁻ concentration peaks, one at a 10- and the other at a 70-cm depth in the Zaria soil, due to textural changes in the profile. There was no appreciable effect of redistribution time of 24 h on the Cl⁻ content peak and its dispersion in the Ikenne and Mokwa soils. The effect of redistribution on Cl⁻ distribution was considerable in the Zaria soil. Leaching efficiency, calculated as the ratio of the depth of chloride content peak and total water applied (20 cm), was the highest (3.6 cm cm⁻¹ of applied water) in the relatively coarse Mokwa soil and the minimum (0.07 cm cm⁻¹) in the layered Zaria soil.
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