Distribution of Potassium Forms along a Hillslope Positions of Newer Basalt on the Jos Plateau Nigeria
Mahmud Abba Tijjani
Landscape positions have always been related to erosional processes, its effects on soil chemical properties particularly the forms of potassium (K) has not well documented in the Savanna soils of Nigeria. This study was therefore conducted to accentuate the forms of potassium distribution associated with hillslope positions. A purposive stratified sampling was employed where crest, upper, middle and lower slope positions were identified, each representing changes in geomorphological position. Results showed that the forms of K varied with landscape position. The mean value of soluble K in the crest surface horizon was 14% (0.1374 cmol (+) kg-1) higher than the value obtained on the lower slope position. For the underlying horizon, soluble K value was 58% (0.0187 cmol(+) kg-1) lower on the crest. The exchangeable K distribution in the surface horizons were not statistically significant, though slightly higher value (0.1316 cmol (+) kg-1) was obtained on the upper slope position while the lowest value (0.1086 cmol (+) kg-1) was observed on middle slope. In the subsurface horizons values were in the order upper slope>crest>lower slope >middle slope. The total K values for the respective surface horizons were non significant while in the underlying horizons mean values varied between 0.6193-1.2048 cmol (+) kg-1. Generally the distribution of the various forms of K did not shown a well-defined trend with respect to topographic positions. Similar profile K distributions were also not well pronounced for the respective positions.
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