NITROGEN-FERTILIZATION OF WINTER-WHEAT IN SPRING IN FINLAND - COMPARISON OF CALCIUM AMMONIUM-NITRATE AND CALCIUM NITRATE, AND THE EFFECT OF SPLIT APPLICATION

The effectiveness of calcium nitrate (CN) and calcium ammonium nitrate (CAN) as N sources for winter wheat in spring was studied in seven field trials in Southern Finland, in the province of Uusimaa. The experiments were carried out on clay soils in 1986-1989. Nitrogen dressings of 120-150 kg ha-1 were broadcasted either as a single application or split into two applications. The two applications were in most cases 30-40 and 90-110 kg ha-1. The single or the first split application was given in the beginning of the growing season and the latter application at the end of tillering. The grain yields obtained by a single N application of 140-150 kg ha-1 ranged from 2 610 to 7 550 kg ha-1 and the protein content of grains from 9.4 to 14.5 %. The nitrogen form of the fertilizer had no significant effect on the grain yield and on the protein content of grains. Splitting the nitrogen increased the grain yield by 400 kg ha-1 and the protein content of grains by 0.8 percentage points.