Phosphorus sorption characteristics as influenced by major soil units in southern Ethiopia

AbstractBackgroundLimited soil nutrients in the soil are threat in crop production in Ethiopian soil. Low availability of phosphorus (P) is one amongst the most important crop yield‐limiting problems among the various reasons limiting P availability in tropical soils, P sorption is that the major one.AimTherefore, this study was done to identify P sorption characteristics of andosols, vertisols, and nitisols in Tachegnawgimbicho, Taba, and DelboAtwaro study sites in southern Ethiopia.MethodsAdsorption isotherms experiment was done using Langmuir and Freundlich models to spot the character of soils in their capability on P sorption and causation and to explain P sorption as influenced by the associated soil properties using SAS version 9.00.ResultsThe P sorption maxima (Xm) of andosols, vertisols, and nitisols were found to be 965, 810, and 706 μg g−1, respectively. Correlation analysis indicated that soil pH was negatively and significantly correlated with Xm (R2 = −0.88). The Langmuir affinity constant “k” was positively and significantly correlated (R2 = 0.981) with maximum phosphorus buffering capacity (MPBC) indicating bonding energy constant is a component of buffering capacity of soils. The Langmuir equation correlated significantly with P sorption maximum “b” and binding energy “k” indicating both parameters can be used for evaluating P sorption characteristics of the soils.ConclusionIn this finding, the path analysis coefficient revealed that clay and pH had direct effects on P sorption parameters. Sorption capacity is high in andosols followed by nitisols and vertisols. Andosols require more P fertilizer to maintain optimum P concentration in soil solution for crop growth as compared with nitisols and vertisols.