Ársrit Ræktunarfélags Norðurlands - 01.01.1967, Side 124

126
í íslenzkum túnum. I. Tilraunir með brennisteinsáburð á
tún sumarið 1966.
Ársrit Ræktunarfélags Norðurlands 63. 49—64 1966.
5. Steenbjerg F.: Planternes ernæring. Almindelige del.
bls. 350. D. S. R. Kdbenhavn 1965.
6. 0delien M.: Orienterende markfors0k med svovel-
gj0dsling. Forskning og fors0k i landbruket. 17:2 79—117
1966.
Summary.
An examination was made o£ the amount of sulphur in a few soil
samples collected in two districts in North-Iceland, Austur-Húnavatns-
sýsla and Suður-Þingeyjarsýsla. Besides the loss on ignition and pH
were determined in the same samples of soil.
The following method for determining the amount of sulphur was
used: Air-dried and ground samples of soil (5 g) were heated up to
300° C for four hours, then shaken with 1 M ammoniumacetat solu-
iton and finally filtrated. The sulphur was measured in the filtrate
using the Versene (EDTA) titrimetric methods for sulphur. Soil Chemi-
cal Analysis, page 264.
The results of the experiments showed that there is a linear relation-
ship between the amount of sulfur and the loss on ignition, cf. fig. 1.
The average amount of sulphur in the above-mentioned samples of
soil was 88 mg s/100 g soil in S.-Þing., and 129 mg s/100 g soil in A,-
Hún., which is in agreement with the fact that the lack of sulphur is
more common in S.-Þing. than in A.-Hún.
There does not seem to be any correlation between the concentra-
tion of sulphur and pH, cf., fig. 2.
A comparison of the age of the grass fields. from which the samples
were taken and the amount of sulphur in them, showed that the least
amount of sulphur will be found in those grass fields which were til-
led as early as the utilization of a fertilizer lacking in sulphur begins
in Iceland.