Abstract
Four different phosphate glass formulations (F0, F1, F2, and F3) were developed according o wheat 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-B-Cu-Mo) 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 chains and that the addition of micronutrients could change the chemical durability of phosphate glasses. A greenhouse experiment was performed using wheat (Triticum durum L.) to evaluate the efficiency of the four glasses, with or without application of chemical nitrogen (N) (N + VF and VF, respectively). The different formulas were tested using two rates of 0.3 and 1 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 four months of cultivation, vitreous fertilizers application significantly improved growth (7% to 88%), photosynthetic (8% to 49%) parameters, and yield (29% to 33%) compared to NPK treatment and to 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 wheat production and can be used in practice as an environmentally controlled-release fertilizer.
Highlights
The world population continues to increase, and at the existing rate of growth, it is expected to increase by over a third, or 2.3 billion people, between 2009 and 2050 [1]
These processes involve three dissolution rate regimes: (i) Initial diffusion, which reflects the exchange between protons in leachate solution and glass network-modifier cations
In all the investigations above, MnO and Fe2 O3 can both improve the durability of phosphate glasses; this study showed that Fe2 O3 was much more effective in decreasing the initial degradation rate, while MnO had a greater effect on decreasing the residual rate
Summary
The world population continues to increase, and at the existing rate of growth, it is expected to increase by over a third, or 2.3 billion people, between 2009 and 2050 [1]. Vitreous controlled-release fertilizers are considered one of the most promising solutions to increase crop yields without any environmental problems [17] These fertilizers ensure the presence and availability of nutrient elements over time [15]. The soil nutrients will be in adequate quantities but contained within exact and controllable limits, depending on crops requirement and development stage [15]. These nutrient elements are classified into three categories: primary elements, i.e., Nitrogen (N), Phosphorus (P) and Potassium (K); secondary elements, i.e., Calcium (Ca) and Magnesium (Mg); and microelements, i.e., Boron (B), Zinc (Zn), Manganese (Mn), Iron (Fe), Copper (Cu) and Molybdenum (Mo).
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