Field experiments comparing ammonium sulphate, ammonium nitrate, calcium nitrate and urea combine-drilled with spring barley

Abstract

1. Twenty-one experiments were carried out in various parts of England and Scotland in 1959–61 comparing two or more of the nitrogen sources ammonium sulphate, ammonium nitrate, calcium nitrate and urea, combine-drilled in compound fertilizers for spring barley.2. Ammonium sulphate and ammonium nitrate combine-drilled at rates from 35 to 105 lb./acre of nitrogen checked early growth slightly in some of the experiments, with no important difference between the two sources, which also gave similar grain yields.3. Calcium nitrate and urea combine-drilled at 45 lb./acre of nitrogen had no large effect on early growth, while at 70 and 90 lb./acre both fertilizers seriously delayed brairding and reduced the plant population in many of the experiments, especially in eastern England. They gave lower yields than ammonium sulphate and ammonium nitrate in many of the experiments in which early growth was affected, and gave lower mean yields at all rates of application.4. In eleven of the experiments, broadcast applications of two or more of the four nitrogen fertilizers were compared. All sources gave similar mean yields.5. There was a slightly smaller yield from combine drilling than from broadcasting ammonium sulphate and ammonium nitrate, and a markedly smaller yield from calcium nitrate and urea.