Rit Landbúnaðardeildar : A-flokkur - 01.05.1967, Blaðsíða 183

Trials at Hvanneyri have showed an increase in yield in an acid soil
in comparison to „Kjarni“ and a complete change in vegitation.
Trials on spreading „Kjarni“ in the spring at 10 days interval (lOth
May — 20th May — 30th May — lOth June) gave the following yields
respectively, 100 — 98 — 94 and 92. When the N-fertilizer is 150 kg/ha
or more. It is of advantage to spread it in two proportions i. e. before and
after cutting.
4. Trials with P- and K-fertilizers show the importance of proper
balance.
5. Trials with increasing doses of N P K (Each dose, 45 N -j- 30 P2O5
-f- 40 K^O) up to 180 kg/ha N have shown that the yield increases with
each dose hut the relative increase diminishes with each dose. These
trials have shown that the yield from the biggest doses decreases with the
years. Ofcourse the weather might he a factor here.
Trials with increasing doses of N P K (Each dose, 75 N -j- 40 P2O5
-j- 50 K^O) up to 300 kg/ha have given similar results to the one with
180 kg/ha N.
The two biggest doses were found to be uneconomical and at the same
time, some evidence of winter damage was observed.
6. Comparison between compound fertilizer and equivalent nutrients
in straight fertilizer shows no appreciahle difference in yield.
7. The use of lime on hayfields has had little or no effects on the vield
except where the soil is very acid. The use of lime increases the amount
of Ca in the yield but the amount of P remains unaltered.
No difference was found between ordinary burnt lime (98% CaO)
and tlie Icelandic one made from shellsand.
8. Small doses of N P K (40 — 50 —- 50) on permanently grazed
pastures have given good results on drained peat soil.
On river irrigated pastures at Hvanneyri and Skriðuklaustur small
dcses of N- and P-fertilizer have given appreciable increase in yield. In
general N- and P-fertilizer give good results where vegitation is mainly
Meadow vegetation (Gramineae).
9. On hay fields at Sámsstaðir CaSO^ has given some increase in yield,
but at Hvanneyri neither CaSOj nor CuSO^ has given any increase.
10. When spreading some 15—20 tons of farmyard manure on a hay
field, it is good to add between 40—80 kg/ha N. If more N-fertilizer is
used a small amount of K- and P-fertilizer is also needed.
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