الفهرس 
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Abstract
Laboratory and Field experiments were conducted in the current study as follows:
1. Laboratory Experiments:
1.1 The first lab experiment was conducted to evaluate the relationship between certain physicochemical characteristics of water and calcium phosphate salts solubility. Six water samples were collected from Suez Canal region. The obtained results indicated that the solubility of phosphate salts increased as ionic strength increase and depended on the type of phosphate salt and physicochemical properties of water samples.
1.2 The second experiment included four-laboratory experiments were carried out to study the transformations of soluble P as affected by physicochemical characteristics of soil and sediment. The obtained results revealed that the amount of adsorbed P increased as ionic strength decrease. The kinetics model that more fitted to the obtained data is pseudo second-order. The adsorbed amount of P was increased as concentration of P increase for both soil and sediment. The adsorption isotherm more fitting data are Freundlich, Langmuir, Temkin and Dubinin – Radushvevich. The adsorbed amount of P was increased with increased pH values and decreased temperature.
2. A field experiment was carried out in Sarabium, Ismailia governorate, Egypt in three stages. The first stage aimed to deplete soil P by soil cultivated with corn plant before cultivation of wheat. The second stage is to evaluate the effect of phosphate fertilizer dose splitting and application time on wheat yield. Finally, the third stage is to study the residual effect of P fertilization on corn yield. The results indicated that the optimum time of phosphate fertilizer for wheat at two splits (one-third of recommended dose before cultivation and two-thirds after 1-month cultivation).