A (1:1:1 w/w) N-P2O5-K2O fertilizer was prepared by cold-mixing ammonium ortho or ortho/polyphosphates (2-5 P atoms in chain), viz., an 8-24-0 or 10-34-0 or 11-37-0 wt.% solution, with a urea-ammonium nitrate solution (32% N), KCl, and water. The crystallization temperatures determined for the ammonium ortho and polyphosphates and for the N-P-K solutions contg. 0-79.6% and 0-79.1% of polyphosphates, were -12.9degreesC to -21.5degreesC and 4.2degreesC to 9.1degreesC, resp. The 18-20degreesC solubilities of ZnSO4.7H(2)0 in N-P-K solutions, determined in relation to polyphosphate content (0-79.1%), ranged from 0.028 to 1.6% Zn.