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Potassium forms and quantity–intensity relationships in some wetland soils of Abeokuta, Southwestern Nigeria

Ajiboye, Anjorin G., Azeez, Jamiu O., Omotunde, Akinwande J.
Archiv für Acker- und Pflanzenbau und Bodenkunde 2015 v.61 no.10 pp. 1393-1408
base saturation, carbon, cation exchange capacity, energy, fertilizers, loamy sand soils, phosphorus, potassium, quantity-intensity relationships, sandy clay soils, soil organic carbon, soil sampling, wetland soils, Nigeria
The study was carried out to assess forms of potassium (K) and K quantity–intensity relationships in six wetland soils in Abeokuta, Southwest Nigeria. Collected soil samples from pedogenic horizons of six profile pits were analyzed using appropriate techniques. The soils were loamy sand – sandy clay with very low to moderate (0.04–2.55%) organic carbon, low–medium (4.29–22.29 cmol kg ⁻¹) effective cation exchange capacity, high base saturation (89.42–99.56%), and low available phosphorus (≤1.90 mg kg ⁻¹). Values of exchangeable-K (0.05–0.20 cmol kg ⁻¹), mobile-K (0.26–1.53 cmol kg ⁻¹), reserved-K (0.51–2.56 cmol kg ⁻¹), residual-K (0.42–2.21 cmol kg ⁻¹), and total-K (1.02–3.32 cmol kg ⁻¹) were low. The buffering capacity of the soils for K (88.10–273.2 cmol kg ⁻¹(mol.L ⁻¹) ½) and labile-K at specific site (4.48–16.43 cmol kg ⁻¹) were moderate and the free energy of replacement (5512.17–8414.94 J mol ⁻¹) was low. The results suggest that the soils have low capacity to fix K and could, therefore, release applied K fertilizer appropriately for crop uptake. The low-K status of the soil can be corrected by application of K fertilizers.