The value of urea nitrate and urea phosphate as nitrogen fertilizers for grass and barley

Abstract

Urea nitrate, urea phosphate, and a mixture of urea phosphate and urea were tested as nitrogen fertilizers to find whether the presence of the anion decreases the damage urea causes to germinating seeds and seedlings and increases the efficiency of urea by preventing loss of ammonia.Urea nitrate was compared with ammonium sulphate for grass grown in pots in the glasshouse and with ammonium nitrate for permanent grassland in the field. In the glasshouse, a large dressing of urea nitrate damaged the early growth of grass in sandy-loam soil. On average of sandy-loam and clay-loam soils with a small dressing of fertilizers, grass recovered similar amounts of N from urea nitrate and ammonium sulphate; with the large dressing it recovered less from urea nitrate.In the field, 100 and 200 lb N/acre were applied to permanent grassland which was cut twice. The herbage was ‘scorched’ by the urea nitrate because its solution is very acid. Urea nitrate at 200 lb N/acre produced less dry matter containing less nitrogen than did ammonium nitrate.Urea nitrate, urea phosphate and urea phosphateurea mixture were compared with ammonium nitrate for barley and grass grown in clay-loam and sandyloam soils. Tests were made of 33, 67 and 100 lb N/acre for barley and 100, 200 and 300 lb N/acre for ryegrass; the fertilizers were applied immediately before sowing. On the light Woburn soil early growth of barley was least good with urea nitrate, which also damaged the early growth of grass.