Application of urea to agricultural soil may pollute the air environment due to ammonia (NH3) volatilization. Zeolite, Humate, biocher and biofertilizer may be used to control N losses resulting from urea transformation to NH3. A laboratory soil incubation experiment was conducted to determine the effects of zeolite, K-humate, biocher and biofertilizer on controlling NH3 losses out of applied urea. Calcareous soil sample from El-Nobaria area, Beheira Governorate was treated with different amendments and incubated under laboratory condition for 13 weeks. Results obtained showed that soil treated with urea in the presence of different amendments significantly reduced NH3 release from urea as compared to the control. During the first 80 days of the incubation ammonia losses were highest in control compared to soil treated with the different amendments. Biocher treatment showed the highest effect in reducing ammonia volatilization from calcareous soil. Therefore, treating calcareous soil with biocher and biofertilizer can decrease were losses as ammonia and increase nitrogen availability in soil, and hence reduces air pollution by ammonia.

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.

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.mmol1 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.