Inorganic phosphorus fractionation in some selected soils from the Eastern region of Ghana 

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Amounts of phosphorus (P) in inorganic form was determined for twelve top soils (0–10 cm), sub-surface soils (10 – 20 cm) and sub soil (20 –30 cm) which had been cultivated for at least 20 years, and their virgin analogues, to ascertain if relative pool sizes or soil P fertility are being changed by cultivation and associated fertilizer application. The soils were representative of major agricultural areas of the New Juaben and Yilo Krobo Districts of Eastern Region, with total P concentrations ranging from 11.60 µg/g to 31.82 µg/g (inorganic P). P forms in the pools and extractants used were as follows: loosely-bound (1.0M NH4 Cl), nonoccluded (0.5M NH4 F + 0.1M NaOH), occluded (citrate-dithionite-bicarbonate + 0.5M NH4 F + 0.1M NaOH), and Ca bound (1.0M HCl). Loosely-bound P was not analysed in this work because of its small concentration in the soils. Akwadum fertilized cultivated soils had higher distributions of P-fractions (Al-P, Fe-P and Ca-P) and all found in the surface soil (0 – 10cm). Inorganic P-fractions were greatly influenced by soil properties such as soil pH, soil electrical conductivity (EC), % organic carbon (% OC) and soil particle sizes. Cultivation resulted in an increase in nonoccluded and decrease in occluded P. Average distribution of P-fractions as a percentage of total fraction in the Huhunya virgin soils was 57.53 % Ca-P, 18.68% Al-P and 18.15% Fe-bound. Huhunya cultivated soils recorded 50.27% Ca-P, 20.43% Al-P and 20.02% Fe-P. Akwadum fertilized cultivated soil had 62.29% Ca-P, 14.07 Al-P and 13.86% Fe-P. Correlation analysis showed significant relationship among inorganic P fractions themselves and some soil physical properties. The conversion of organic to inorganic P may be reversed by management practices allowing a build up of soil organic matter. Since little change in amounts of loosely-bound inorganic P was observed during cultivation, the more stable pools may represent a better estimate of long-term soil fertility
A thesis submitted to Department of Chemistry in partial fulfilment of requirement for the award of degree of Master of Philosophy (Mphil) Analytical Chemistry.