Ársrit Ræktunarfélags Norðurlands - 01.01.1967, Síða 76

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Summary.
The second effects of sulphur fertilizer applied in 1966 were exami-
ned during the summer of 1967 on two plots in North-Iceland.
Besides, a few experiments and surveys were conducted for the pur-
pose of finding the distribution of sulphuric lack in North-Iceland.
In the summer of 1967 second effects for 16 kg S in gypsum applied
in 1966 were 15 and 13 hkg hay/ha respectively on these two plots.
Apparently the sulphur has only partially been washed away from the
soil during the period.
Results of experiments with potassium sulphate, on other plots in
North-Iceland, showed a definite yield increase; up to 24 hkg hey/ha
or 47%. Increasing lack of sulphur in grass fields is, among other
things, due to the fact: that for the last 20—25 years fertilizers have only
contained very small amounts of sulphur; the application of manure is
less common; the increasing use of N-fertilizer. During the last few
years, the average amount has been 110 kg N/ha.
Figure 2 shows the spots in North-Iceland where the lack of sulphur
has been verified. Regions with comparatively small rainfall and, as
it were, continental climate have been the ones most liable to suffer
from lack of sulphur.