Íslenskar landbúnaðarrannsóknir - 01.09.1971, Page 75

RANNSÓKNIR Á VALLARFOXGRASI 73
was at the shooting stage and the second cut taken 7 weeks later. Split nitrogen
applications resulted in a more even distribution of C. P. yiekl between the first
and the second cut.
The moisture content of Phleum pratense decreased by 2,45% for each week
by which the first cut was delayed. The moisture content was higher at the first
cut but lower at the second cut when all the nitrogen was applied in one dressing.
On the whole the total mineral content of Phleum pratense was decreased the
later the second cut was taken. Thus the P content clecreased by 0,03% per week
and the Ca content by 0,02% per week. Na was the only mineral investigated
which appeared to increase tlie later the first cut was taken. Chemical composi-
tion and moisture content are dependent upon the number of live leaves. A
reduction in the number of live leaves per tiller was associated witli a delay in
tlie time of cutting.
The results indicate that Phleum pratense conserved as silage should be cut at
the shooting stage. Thus a reasonable crop of aftermath should be obtained some
7—9 weeks later. With silage making it may be desirable to use nitrogen in split
applications since this leads to a more favourable ratio between carbohydrates
and protein in the forage.
If the hay is dried in the field or in the barn it appears advisable not to cut
Phleum pratense until 7—14 days after shooting. Due to the lower moisture con-
tent it becomes easier to dry the hay but, on the other hand, the nutritive
value of the forage is somewhat less than that ol' forage cut earlier. Only a light
crop of aftermath can be expected when the first cut is taken so late in the season.