Reduced tillage was compared with traditional ploughing in terms of erosion and phosphorus (P) and nitrogen (N) losses in an experimental field in southern Finland. One part of the field has been ploughed (treatment PF) and the other part harrowed (treatment NPF) every autumn since 1986. Flow volume and water quality data was collected separately from surface runoff and subsurface drainage waters during 1991-1995 (surface runoff volume since 1993). Erosion was higher in PF (on average 234 kg ha-1yr-1 in drainage flow and 479 kg ha-1 yr-1 in surface runoff) than in NPF (158 kg ha-1yr-1 in drainage flow and 160 kg ha-1yr-1 in surface runoff). Total N loss in drainage flow was also higher in PF (7.2 kg ha-1yr-1) than in NPF (4.6 kg ha-1yr-1). Total P losses did not differ much

Accession to the European Union caused a drop of nearly 60 per cent from 1994 to 1995 in prices of wheat, barley and oats in Finland. The economic use of fertilizer therefore decreased accordingly. To calculate the effect of the price changes on the economic optima, the physical production function must be known. Three physical production functions, the quadratic, the linear response and plateau (LRP) and the exponential function were estimated for this purpose. The models differed little in respect of the R2adj value (0.82-0.90) but the calculated optimum varied, depending on the production function. Data on a long-term field trial (21 years) were analysed. The field trial was established in 1973 to demonstrate the effect of mineral fertilizer in crop production. The crops grown in the trial were barley, wheat and oats. Different varieties were included in the models.

Abstract. 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-'. 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~' 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~' and the protein content of grains by 0.8 percentage points.