Adjustable N:P2O5 Ratio Urea Phosphate Fertilizers for Sustainable Phosphorus and Nitrogen Use: Liquid Phase Equilibria via Solubility Measurements and Raman Spectroscopy.

Design and use of the adjustable N:P2O5 ratio fertilizers is crucial in proper nutrient management if sustainable phosphorus use is to be ensured. Overfertilization with phosphorus can lead to its fixation in soil, as well as the unwanted environmental phenomena, such as eutrophication. Urea phosphate, CO(NH2)2·H3PO4, based liq. fertilizers were synthesized in this work, and their resulting physicochem. properties were detd. For this purpose, phase compn. information on the CO(NH2)2·H3PO4-CO(NH2)2-H2O ternary system was analyzed, and crit. points on the polytherm were detd. Liq. fertilizer compns. were detd. and their corresponding physicochem. properties established. Raman spectroscopy showed that CO(NH2)2·H3PO4 partially retains its strong bonding interactions between both mol. adducts in aq. solns. suggesting their improved nitrogen management efficiency in soils. Effect of these acidic pH fertilizer solns. on the pH of soil was detd. and was found negligible. The potential of these fertilizers for reducing the loss of nitrogen from the wet soil is also discussed. [on SciFinder(R)]