The aim of this work was to conduct pot experiment to study the ability of plant roots on solubilizing various sources of phosphorus and factors that may facilitate or inhibit their activity. A split medium – split root technique experiment was conducted to study the effect of CaCO3, pH, organic matter (humic acid) and bentonite on the pH, P solubility in the medium and P concentration in bean plants (Vicia faba var. balady). The changes in pH of the lower solution was recorded, also the root exudate was collected in 500 ml of CaCl2 solution 0.5 × 10-4 M and pH 6.85.  Results showed that the highest recorded total dry weight was found when both N forms were applied in the ratio of 1:4 NO-3: NH+4 or NO-3 alone. The mechanism of solubilizing rock phosphate by exudating protons or organic, amino and other organic compounds is possible at the root surface even in alkaline soil as long as the rock phosphate material was added near the root and organic matter was added to limit the fixing power of the inorganic components as CaCO3 and excess soluble Ca. Also, the availability of P from rock phosphate sources depends on its reactivity value.

In this work, sodium bentonite (Bn) was used for removal of alizarin red S (ARS) from aqueous solution using batch technique. Fourier transform infrared spectroscopy and X-ray diffraction were used to characterize sodium bentonite. Different parameters that would affect ARS dye removal such as initial pH, contact time, initial ARS dye concentration, bentonite dose, and temperature were explored. The realized data from kinetic studies demonstrated the high fitness of pseudosecond-order kinetic model for better interpretation of the experimental data. The adsorption isotherms studies showed that Freundlich isotherm had a high correlation coefficient among the studied isotherm models. Thermodynamic studies proposed that ARS adsorption onto Bn was spontaneous in nature at the lower temperatures and exothermic.

Understanding the sorption process in natural zeolite and bentonite is necessary for effective utilization of these minerals as nutrient adsorbents and on the other side for controlling release of plant nutrients. This research was undertaken to characterize the ability of natural zeolite and bentonite minerals to adsorb and release zinc and manganese. The potentials for sorption of these ions were evaluated by applying the Langmuir and Freundlich equations. The results showed that Langmuir constant [maximum adsorption (b mmol kg-1)] of both Zn and Mn were for bentonite > zeolite While the [binding strength values (k in L.mmol-1)] for zeolite > bentonite      Zn in case of zeolite showed the lowest desorbed percentage particularly at high levels of sorbed Zn. Only, 74.7 % is readily extractable by DTPA after three successive extractions leaving, 25.3 % Zn retained by the mineral. In case of bentonite, 82.26 % of sorbed Zn is readily extractable by DTPA after three successive extractions leaving, 17.74 % Zn retained by the mineral. In case of Mn, 84.63% of Mn sorbed by zeolite is readily extractable by DTPA after three successive extractions leaving, 15.37% Mn retained by the mineral. In case of bentonite, 89.79 % of adsorbed Mn is readily extractable by DTPA after three successive extractions leaving, 10.21 % Mn retained by the mineral.      This finding may reflect clearly the possibility of using natural zeolite and bentonite as a slow release fertilizer for Zn and Mn and on the other hand preventing soil pollution with heavy metals.