Ársrit Ræktunarfélags Norðurlands - 01.01.1971, Side 60

HEIMILDIR
1. H. C. Aslyng: Klima, jord og vandbalance í jordbruget; Köbenhavn 1968.
2. Gunnar Bjarnason: Búfjárfræði, Akureyri 1966.
3. Óttar Geirsson: Tilraun með jarðvinnslu; Ársrit Ræktunarfélags Norður-
uands 1966.
4. Steindór Steindórsson: Gróður á íslandi, Reykjavík 1964.
SUMMARY
This article deals with the results from two fields experiments in
Hvanneyri in West-Iceland (64°34' northern latitude and 21°40' west-
ern longitude).
In the first one, experiment no. 58-57, the experimental treatments
were as follows:
a. Permanent grass.
b. I. year barley, 2. year kale, 3.-6. years grass, barley etc.
c. 1. year barley, 2. year potatos, 3. year oats, 4. year kale, 5.-8. year
grass, 9. year barley etc.
Table 1 is a schema of the treatment of experiment no. 58-57.
In the other one, experiment no. 145-63, the experimental treat-
ments were as follows:
a. Only plowed.
b. Plowed + once tilled with a rotatiller.
c. Plowed -f three times tilled with a rotatiller.
d. Plowed -)- six times tilled with a rotatiller.
e. Plowed + three times harrowed with a dishharrow.
Both experiments were located on peat soil.
The main aim of the experiments was to find the effects of a rotat-
iller on the soil and the yield.
In ten years periods the highest yield was gotten from the plots with
permanet grass in experiment no. 58-57.
By tilling the soil often (as in plots b and c) the porosity of the soil
were changed. The soil-pores becomes smaller, see table 4 and fig. 1.
It was difficult to get rid of weed (stellaria medium and poa annua)
in the plots that were tilled often.
Experiment no. 145-63 showed that no profits were by tilling often
but the yield was almost the same whether the soil was tilled once, three
times or sex times, see table 5.
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