Polymethylene urea fertilizer solution

Abstract From the Canadian patent

A two stage method for preparing clear storage, stable, controlled release polymethylene urea nitrogen fertilizer solution. In the first stage, urea is reacted with a molar excess of formaldehyde, with temperatures of 75 to 100°C, at near-neutral pHs provided by buffers such as sodium bicarbonate, in the presence of ammonium compounds until the formaldehyde is substantially converted to methylene moieties. In the second stage, the methylene moieties are reacted with additional urea and ammonium compounds with temperatures of 75 to 100°C, in a near-neutral buffered solution at a pH of between 6.9 and 8.5 until the added, urea is substantially converted to water-soluble branched chain …