Phosphorus (P) deficiency is the major constraint to crop production in most tropical
soils (Sahrawat et al., 2001). In Angola, such constraint (i.e, low concentration and low P
solubility) has also been reported to limit crop production in many agricultural soils
(Ucuassapi, 2006). These soils may require application of inorganic P through soluble and
relatively reactive phosphate rock sources, and lime (Dobermann et al., 2002; Murphy,
2007). However, appropriate P management strategies may require information on the
fate of applied P and its interaction with the colloidal constituents. Therefore, information
on the different P fractions (inorganic and organic) after the application of different rates
of P fertilizers and lime, as fractionated sequentially by the Hedley modified procedure
(Tiessen and Moir, 1993) is crucial for making appropriate fertilizer and lime rate
recommendations for crops (Islam et al., 2010)
