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

Abstract

Design and use of the adjustable N:P 2 O 5 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(NH 2 ) 2 •H 3 PO 4 , based liquid fertilizers were synthesized in this work, and their resulting physicochemical properties were determined. For this purpose, phase composition information on the CO(NH 2 ) 2 •H 3 PO 4 −CO(NH 2 ) 2 −H 2 O ternary system was analyzed, and critical points on the polytherm were determined. Liquid fertilizer compositions were determined and their corresponding physicochemical properties established. Raman spectroscopy showed that CO(NH 2 ) 2 •H 3 PO 4 partially retains its strong bonding interactions between both molecular adducts in aqueous solutions suggesting their improved nitrogen management efficiency in soils. Effect of these acidic pH fertilizer solutions on the pH of soil was determined and was found negligible. The potential of these fertilizers for reducing the loss of nitrogen from the wet soil is also discussed.

Enhancing Biochar as Scaffolding for Slow Release of Nitrogen Fertilizer

“…34,35 These changes in peak positions are attributed to the formation of complex or adduct of urea, with paraffin wax hydrocarbon (C n H 2n+2 ) 35 or due to the strong H-bonding between H 3 PO 4 and urea. 36 These observations suggest possible H-bonding of urea to H 3 PO 4 activated biochar, particularly between the N−H group of urea and the O atom of H 3 PO 4 , and the CO group of urea and the O−H group of H 3 PO 4 .…”

“…Slight changes in the 1000–1150 cm –1 region of the FTIR spectra were observed: the 1148 cm –1 peak shifted to 1154 cm –1 and the 1001 cm –1 peak shifted to 1013 cm –1 for both H 3 PO 4 activated SRFs compared with urea. These peaks are assigned to symmetrical NH 2 rocking and symmetrical C–N stretching vibrations. , These changes in peak positions are attributed to the formation of complex or adduct of urea, with paraffin wax hydrocarbon (C n H 2 n +2 ) or due to the strong H-bonding between H 3 PO 4 and urea . These observations suggest possible H-bonding of urea to H 3 PO 4 activated biochar, particularly between the N–H group of urea and the O atom of H 3 PO 4 , and the CO group of urea and the O–H group of H 3 PO 4 .…”

Mechanosynthesis of Magnesium and Calcium Salt–Urea Ionic Cocrystal Fertilizer Materials for Improved Nitrogen Management

“…A conceptually interesting approach in obtaining novel EEF is the alteration of urea’s reactive properties by confining it in a single molecular crystal unit with the inorganic acids or their metal salts, such as Ca or Mg phosphates, sulfates and nitrates. Reports exist where a molecular crystals of urea and phosphoric or nitric acid was shown to result only 0.7% nitrogen loss as ammonia as opposed to up to 61.1% of soil treated with urea only, , which suggests that major improvements to the global nitrogen cycle are achievable. , Additionally, urea molecular ionic cocrystals with inorganic Mg and Ca salts also contain other primary and secondary nutrients, such as P, Ca, Mg and S, which are necessary for a balanced nitrogen uptake . The classical way of obtaining these crystalline Ca and Mg salt–urea ionic cocrystal materials is their precipitation from saturated aqueous solutions via heating and slow evaporation. , Mechanosynthesis, on the other hand, is a dry preparation method with plenty of opportunities in clean synthesis that have already been applied in EFF engineering, − but very few compounds made were well-defined crystalline materials, such as KMgPO 4 , NH 4 MgPO 4 and layered double hydroxides (LDH), Mg–Al–NO 3 (Mg:Al = 3:1) .…”

Mechanochemistry as an emerging tool for the preparation of sustained release urea cocrystals as a nitrogen source

“…Along with the ionic cocrystals, Navizaga et al synthesized a urea phosphate CO(NH 2 ) 2 ·H 3 PO 4 , based liquid fertilizer. 63 The adjustable N:P 2 O 5 ratio fertilizers are crucial in proper nutrient management with sustainable phosphorous use. The as-synthesized liquid fertilizers were characterized using Raman spectroscopy and ternary phase diagram.…”