GB890569A - Improvements in and relating to fertilizers - Google Patents

Abstract

A fertilizer comprises urea and an acid-reacting substance containing in the molecule at least one hydrogen atom replaceable by ammonia in a proportion of at leas 0,2 mole equivalent of said substance per mole of urea. Preferred acid substances are mono-ammonium dihydrogen phosphate, mono-potassium dihydrogen phosphate, mono-calcium phosphate, triple superphosphate, superphosphate, mono-sodium dihydrogen phosphate, ammonium hydrogen sulphate, potassium hydrogen sulphate, and sodium hydrogen sulphate. With a mixed loam of pH 6,7 at least 0,21 mole equivalent of acid substance is required per mol of urea and in a sandy soil of pH 5,7 abut twice as much acid additive is required. Other compounds which may be added are ammonium sulphate, potassium sulphate and potassium chloride. The fertilisers may be made by wet granulation in a rotary drum, pan or paddle type mixer and the mass compacted by passing through rolls capable of applying 400 to 25,000 pounds per linear inch to produce sheet like aggregates of about 0,1 inch thickness which can be broken down to free flowing granules. The anti-caking properties may be enhanced by coating with up to 4% by weight of an inert powder such as china clay applied with or without an adhesive such as oil. The fertilisers are particularly suitable for cereals, grasslands and potatoes. The biuret content of the urea should preferably not exceed 1,5%. Specifications 360,147, p 807,107, 816,573 and 822,969 are referred to.