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4607626 
Journal Article 
Influence of Soil Components on Phosphorus availability in some soils of Egypt 
Gao, LL 
2013 
1 
Research Journal of Chemistry and Environment
ISSN: 0972-0626 
17 
9 
58-65 
WOS:000323501200011 
Structure of calcite mineral is very important to study the supplying power of phosphorus in the soil. In addition, calculating the bonding energy and the Phosphorus Recovery Index (PRI) may assess the phosphorous deficiency in the soil. These parameters can be used as indicators for the supplying power of phosphorus and its dynamics in the soil-plant system rather than the classical determination of available phosphorus. Soil components, namely, clay, calcium carbonate (calcite mineral) and iron oxides contents were investigated as they are among the main factors affecting phosphorus availability in the soil. Therefore a structure of calcite mineral is proposed in the current study to understand the mechanism of phosphorus adsorption and desorption process. Three soil types, namely alluvial (Typic Haplotorrerts), calcareous (Typic Haplocalcids) and sandy (Typic Torripsamments) represented by two soil profiles for each were used. These soils represent the main soil types most prevailing in Egypt.



The isotherm equations of Freundlich and Langmuir were applied to determine the bonding energy and the adsorbed phosphorus quantities as well as PRI values were calculated for the soils under investigation. The results showed that the highest values of phosphorus adsorption and bonding energy were found in the calcareous soil which is followed by alluvial and sandy soils respectively. On the other hand, the desorption of phosphorus from soils decreases significantly in the following order; sandy>alluvial> calcareous soils. In contrast, the PRI value is highest in sandy soils followed by alluvial and calcareous soils, respectively. According to the calculated PRI values, it is found that calcareous soil has the extreme phosphorus deficiency. 
Adsorption; structure; bonding energy; calcium carbonate; PRI