Changes in soil phosphorus fractions across a toposequence in the estuary plains of Pakistan
2016
Jamil, Sohail | Mehmood, Ayaz | Akhtar, Mohammad Saleem | Memon, Mehrunisa | Imran, Muhammad | Rukh, Shah | Qayyum, Abdul | Jenks, Matthew A.
Understanding the regional dynamics of soil phosphorus (P) chemistry is essential for developing the best fertilizer management practices aimed at enhancing P use efficiency in cropping systems. The soil content of apatite, an important P-containing lithogenic mineral, can be influenced by its position in the local relief of a landscape. The objective of this study was to determine quantitative distribution of various P-forms in estuary plains of southern Pakistan in relation to soil genesis. Soils at different positions within the estuary plain were sampled at various genetic horizons. Apatite-P was the most abundant inorganic P constituent (380-590 mg kg ⁻¹) in all cases, followed in decreasing abundance by iron oxides surfaces adsorbed phosphorus (Fe-P), octacalcium phosphates (Ca ₈-P), aluminum oxides with surface bound P (Al-P) and the least abundant was the phosphorus occluded in iron oxides mineral (Occl-P). The abundance of apatite-P and these other forms of secondary phosphate varied for the soils at different relief positions in these estuary plain landscapes.
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