Íslenskar landbúnaðarrannsóknir - 01.03.1969, Síða 82

80 ÍSI.ENZKAR LANDBÚNAÐARRANNSÓKNIR
S U M M A R Y
GROWTH CONDITIONS FOR GRASSES
AT EDGE OF A SNOWDRIFT
Bjarni E. Guðleijsson and Sturla Friðriksson
Agricultural Research Institute, Reykjavik, Iceland.
Winter injury of grass is common in Icelandic hayfields and seriously affects
yield of hay. A persistent cover of snow and ice after a period of thaw during
late winter seems to be a necessary prerecjuisite for such damage. During the
winter 1966—67 snow fell heavily in north-eastern Iceland and snowdrifts
lasted late into the spring. One particular snowdrift remained for some time
in the hayfield on the farm Skörð in Reykjahverfi, South-Thingeyjarsýsla,
providing conditions for microclimatic studies. The drift and ice in the soil
were measured and rate of melting compared with soil tenrperatures at 5 cm
depth and other climatic measurements in air. Respectively, the growth of grass
was investigated as the melting proceeded. Winter injury was not noticed in
sward where snow had remained until spring frosts were over. Injury was, how-
ever, noticed 12—18 m away from the drift where ice sheet was present in the
ground and where melting of the drift had taken place while air temperatures
still fell below 0° at nights. The snow cover delayed somewhat the onset ot'
growtli. This was reflected by a difference in yield and length of leaves and
protein content of grass which was uncovered fronr the snow at various times.
It is pointecl out that this delaying effect of the onset of growth by snowdrifts
to some extent provides a more varied grassland with a prolongation of the
period when grasses are of high nutritive value. Snowdrifts that remain long
into the summer on mountain ranges can thus positively affect the late grazing
value of the pasture.
HEIMILDARRIT:
Veðráttan 1967. Veðurstofa Islands, Reykjavík.