Rit Landbúnaðardeildar : B-flokkur - 01.05.1946, Síða 109

V. Summarv and Conclusions.
Experiments and investigations relating to the cultivation of corn (barley, oats,
rye, and wheat) are described.
1. The cultivation of corn was practised in Iceland from the time the country was
settled until the beginning of the 15th century, or for good 500 years.
Many places the environment was unfavorable, and the growning of corn was gradu-
aliy discontinued in the colder districts. It persisted most stubbornly in the soutli
and south-west part of the country, but was altogether suspended in the beginning
of the 15th century, when the country was harassed l)y the „great plague“ („black
death“). — In accordance with this, trials with barley and oats during the past 15
years have shown, that full maturity of these crops is obtained most frequently in
the south- and south-west districts of the country. — Six-row barley was the principal
crop grown.
The Danish rule in Iceland, unusually cold years due lo the presence of the polar
ice, volcanic eruptions, and plagues caused a gradual decline in the economic status of
the people. Togetlier with decreasing productivity of the land and poor communications
with other countries, this resulted in a decline in cultural techniques. In years, when
barley did not ripen, it may have been dif'ficult to obtain grain for seed in this isolated
country. When corn no longer was grown, the practices involved in its culture also were
forgotten. Customs and traditions relating to corn-growing were removed from the
yearly cycle of farm work. This is the main í'eason why attempts to get Icelandic
farmers to resume corn-growing have met with success onlj' in few cases.
2. The weather (more specifically, temperature and rainfall) during the two or
three last months of the growing season primarily decides whether ,or not barley and
oats will ripen.
Provided six-row barley is not sown later than May 10, it. can ripen fully if tlie
mean temperature for July and August is not less than 51 degrees Fahrenheit, and the
rainfall is not more than 2 to 2% inches each month. From one half to two thirds
greather rainfull, but an unchanged temperature, will give a yield of grain, that is approxi-
mately one third of the fully matured crop. Cool springs and warm late summers have
proved to be favorable for the growing of corn, whereas warm springs and cool Julv
and Aug'ust are unfavorable. If the mean temperature for July and August exceeds 52
degrees Fahrenheit, barley and oats tvill mature although the rainfall is 3% inch each
month.
Dry and fully ripe grains of barley and oats are not injured by a frost of 2 to 3.5
degrees Fahrenheit. This temperature, however, will injure the grains, and halt their
ripening if thev are wet and immature.
Based on records from seven weather stations, covering from 13 to 20 of the past
years, the chances for barley and oats to ripen fully appear to be:
9 years out of every 10 in the south- and south-west part of Iceland.
3 — — — — 5 in the northern and eastern districts, and
1 year out of every 2 in the western part.
Experiments on the time of seeding have been carried out for three years in Ileykja-
vík, and for fourteen j'ears in Sámsstaðir. They have shown that Donnes-barley viclds
most when sowit from April 20 to May 10. Later seedings have in most instances yielded
mature seeds, however, of a smaller size, and with a iower starch content. The yield
of grain decreases, and the yield of straw increases with delayed seedings.
Tlte first seeding every j'car has been put in April 20, and it usually has yielded
most grain with the greatest volume jveight. The single-grain weight usually has been
comparable with that of grains of the sarne variety grown in other counlries, but the
volume weight is sliglitlj' less in Iceland.
Other varieties of barlej' and oats, tested in Iceland, have shown the same general
dependance on the time of seeding as has been described above for Donnes-barley,