Ársrit Ræktunarfélags Norðurlands - 01.01.1965, Page 81

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Summary.
This article deals with the amino acid content of heat dried and
finely ground grass samples from the experimental farms at Reykhólar
in the western part of Iceland and Akureyri in the northern part of
Iceland. The samples were from experiments with application of in-
creasing amounts of ammoniumnitrate fertilizer to permanent grass
fields. In the year 1960, when the grass samples were taken, the experi-
ment had been carried out for 9 years at Reykhólar and for 7 years at
Akureyri. The amounts applied to the plots in question, were as fol-
lows: Reykhólar: 0, 40, 80 and 120 kg N/ha and Akureyri: 80 and 120
kg N/ha. The amino acid analysis were made at Department for Soil
Fertility and Plant Nutrition, The Royal Veterinary and Agricultural
College, Copenhagen, with an automatic amino acid anlyzer, based on
ion exchange chromatography with gradient elution (1).
Results:
1. Nitrogen fertilizer application increased the content of amino
acid in dry matter considerably, tabla 1. Application of 120 kg N/ha,
as compared to no nitrogen application, resulted in a 20—30% increase
of amino acid content in dry mattar for most of the amino acids, some-
what less for arginine, 12%, and for leucine, 16%. The corresponding
increases for tyrosine, 4%, and for proline, 7%, are probably not signi-
ficant. Greater increases are registered for a-amino butyric acid, 47%,
and for aspartic acid, 61%.
2. An application of 40 kg N/ha increased the content of all amino
acids in crude protein, except for proline, tyrosine and arginine, table
2. When nitrogen is applied, a relatively greater part of the nitrogen,
absorbed by the grasses, is used for the produktion of the amino acids
analysed, than the part used for such a production, when no nitrogen
is applied. Increasing the nitrogen amount aj)plied from 40—120 kg
N/ha, caused an increase in the content of aspargic acid in the crude
protein and a slight decrease in the content of glutamic acid, proline,
leucine, alanine and phenylalanine, but these decreases and the changes
in content of other amino acids are only small and my not be signifi-
cant.
3. There are observed differences in crude protein content, amino
acid content in dry matter (table 1) and amino acid composition of
crude protein (table 2) in the corresponding samples from the two ex-
perimental sites. The crude protein and amino acid content in dry
matter of the samples from Akureyri was lower, than in the samples
from Reykhólar. The amino acids account for a greater part of the
crude protein in samples from Akureyri, than in the samples from