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Description
Four different phosphate glass formulations (F1, F2, F3, and F4) were developed according to maize nutrient requirements to be used as controlled-release fertilizers. These glasses contain macro-elements (P2O5-K2O-CaO-MgO), with the addition of microelements (Fe-Mn-Zn-Cu) in each formulation. The effects of these elements’ addition on thermal properties, glass structure, and dissolution behaviors were investigated. Results showed that these glasses are composed essentially of metaphosphate and pyrophosphate chains and that the addition of micronutrients could change the chemical durability of phosphate glasses. A greenhouse experiment was performed using maize to evaluate the efficiency of the four glasses, with or without the application of chemical nitrogen (N) (N + VF and VF, respectively). The different formulas were tested using 1.4 g per plant. In addition to the vitreous fertilizer formulations, two other treatments were applied: control treatment with no amendment and Nitrogen-Phosphorus-Potassium treatment with the application of the conventional fertilizers on the base of optimal rates. After three months of cultivation, the application of vitreous fertilizers significantly improved growth compared to NPK treatment and the control. It has been found that formulas F1, F2, and F3 may constitute a potential alternative to conventional fertilization due to their positive impact on maize production. They can be used in practice as an environmentally controlled-release fertilizer.
