Nitrate, ammonium and urea nitrogen as fertilizers for wheat and rye in a field experiment

In a five-year field experiment on a well-limed sandy soil five nitrogen fertilizers were compared. They were urea, ammonium sulphate, calcium nitrate, calcium ammonium nitrate and a mixture of ammonium sulphate and calcium nitrate. The crops in successive years were spring wheat, winter rye, winter wheat, spring wheat and winter rye. The average yield level was not different because of different fertilizers, but in individual years some differences were found. Average contents of nitrogen and calcium in grain and straw, however, showed a slight superiority of calcium nitrate to ammonium sulphate. Other fertilizers did not deviate significantly from either of these. Placement vs. broadcasting, application time and rate of fertilizer nitrogen were also investigated. These factors did not affect the differences between fertilizers. The soil-acidifying effect of the fertilizers decreased in the order: ammonium sulphate, urea, mixture of AS and CN, calcium ammonium nitrate. Calcium nitrate had no effect on soil acidity