Ársrit Ræktunarfélags Norðurlands - 01.01.1973, Síða 45

háttar kalárum, mest árin 1918, 1920, og árabilið 1966—
1970, og er rýrnunin á þessum árum frá 14 til 34%. Er hey-
fengur til dæmis á öllu landinu um 1500 þús. hkg undir
meðallagi árin 1969 og 1970. Heyfengur minnkar hlutfalls-
lega meira í einstökum hreppum, sem verða hart úti í kal-
árum, önnur ár eru kalskemmdir engar og í sumum héruð-
um eru þær mjög fátíðar.
SUMMARY
This paper describcs an investigation on the frequency o£ years
with winter damages on cultivated grassland in Iceland and their
effect on hay yields.
Since the turn of the century (1900—1972). 20 years with some winter
damages have been recorded (36%), of which one half (18%) were
serious ones. During the last years the frequency of serious winter
damages has increased, and in the 1960—1972 period 58% of the
years were serious in this respect.
Hay yield in the country decreased in most of the years with serious
winter damages, particularly in 1918 and 1920 and from 1966 to 1970,
in which 14 to 34% decrease in hay yield was observed. For instance
the total amount of hay harvested in the country in 1969 and 1970
was approximately 1,5 million hkg below average. The hay yield de-
creased proportionally more in some districts, due to winter damages,
in same places amounting to 30 to 60%.
According to evaluation of winter damages in northern Iceland,
the grassland in some districts were 50 to 70% damaged in some of
the most serious years. Variation in this respect within years and
districts is great. Even though a year is evaluated as a serious one,
some parts of northern Iceland can be completely devoid of any
damages that year.
ÞAKKARORÐ
Höfundur þakkar Derek Mundell fyrir aðstoð við teikningu á mynd-
um. Derek teiknaði einnig myndir í grein um sama efni í síðasta hefti
Arsritsins og á liann einnig þakkir skildar fyrir það.
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