Cropping covers are used in an attempt to promote the growth of cultivated plants, and to raise ground temperature. Their usage has achieved a raise of several degrees in soil surface temperature, compared with bare ground. This is especially important to grape vine cultivation in cooler climates. The study set out to find out how much black plastic ethylene foil, transparent greenhouse plastic and south facing wall of a building raise subsoil temperature. The measurements were made using waterproof temperature loggers set in the ground at 40 cm depth in Tuusula community, in the Helsinki region (60°24ʼN; 25°01ʼE).
This area is located at the northern rim of the European hemiboreal vegetation zone. The temperature loggers recorded the soil temperature eight times a day, throughout the year. The measurements showed that these covers did not raise the vineyard subsoil temperature significantly in comparison with grass cover or bare ground, but subsoil temperatures made at the building wall were significantly lower (P<0.05) than all the others. Based on the results, the covers used did not have a significant effect on soil temperature when applied to vines planted in 40 cm depth which is used in the North, nor did growing by the wall bring the advantage commonly believed in.
Key words: Nordic viticulture, cropping covers, subsoil temperature, greenhouse effect