Amounts of distribution of some forms of phosphorus in ferruginous soils of the interior savanna zone of Ghana l

Abstract

The forms and distribution of phosphorus in three well-drained and two poorly drained, widely cultivated Lixisols on two landscapes in the interior savanna zone of Ghana were studied. Total phosphorus (TP) and dithionite-citrate-bicarbonate extractable P (DCB-P) concentrations increase with depth in all the soils and are related to profile maturity in the well-drained soils. In the low-lying soils, however, the concentration is governed by drainage. The greatest amounts of TP occur in the topsoils of the Tingoli series on Catena 1, which were 132, 92, 744, and 700 mg/kg in the fine earth, silt, clay, and nodule fractions, respectively. The Kpelesawgu series on Catena 2, however, has the least TP accumulation of 78, 159, and 50 mg/kg in the fine earth, silt, and clay fractions, respectively. The large concentration of TP and DCB-P in the nodules and clays is due to their greater sesquioxide contents. The available P concentration is extremely low because of the low content of P-bearing parent material. The amounts of clay, silt, and DCB-P may be used to estimate the accumulation of TP concentration in the soils. Variations in TP saturation correspond with changes in clay accumulation in the soils on Catena 1 and in silt content in the Catena 2 soils.


Ghana Jnl agric. Sci. Vol.30(2) 1997: 135-143