THE EFFECTS OF IRRIGATION, FERTILIZATION AND ORGANIC MATTER ON ROSES GROWN IN FOUR SOILS IN THE GREENHOUSE

Roses of the Baccara variety were grown during 4 years in 4 soils of different properties, but in the same greenhouses and location: a sandy soil of the coastal region (8% clay), a loessial sandy loam (16% clay), a grumusolic clay loam (39% clay), and a heavy clay grumusol (69% clay).

During the first 2 years the 2 lighter soils gave higher yields with better quality than the clay soils. During the last 2 years the loessial soil gave the highest yields. The addition of 70 1/m2 of peat affected the organic matter content and the water retention properties of the light soils, but not the flower yields.

Irrigation twice weekly during the summer had a small advantage part of the time on some of the soils, as compared with irrigation once a week. When during the last year of the experiment the latter plots were irrigated very frequently (every 2–3 days), they gave better yields than the twice-weekly irrigated treatment.

The yield and quality differences were analysed in relation to soil physical properties and fertility status.