Ársrit Ræktunarfélags Norðurlands - 01.01.1966, Page 90

Summary.
This article deals with the results of a field experiment and a pot
experiment which were made on a peat soil at Hvanneyri, West Ice-
land, in the years 1960—1965.
The total porosity of the peat soil in the experimental field is
approximately 80 per cent by volume, the specific gravity 1.5, the
volume weight or bulk density 0.3 g/cm3 and weight loss on ignition
67 per cent. PH of the soil was 4.9 in the beginning of the experiment.
The peat soil is 2—3 meters thick and drained by open canals.
The experimental treatments were as follows:
I. A. Plowing in 50—70 cm (deep plowing), surface tilled with a
rotatiller.
I. B. Plowing in 50—70 cm (deep plowing), surface tilled with a
harrow.
II. A. Plowing in 20—30 cm, surface tilled with a rotatiller.
II. B. Plowing in 20—30 cm, surface tilled with a harrow.
The soil was cultivated in 1959 and then were grasses sown in the
field. During the 6 experimental years the field was permanent grass-
field.
The results can be summarised as follows:
The hay-yields were a little higher on the deep plowed plots than
on the plots plowed in 20—30 cm, 41.0 hkg/ha on deep plowed plots,
38.0 hkg/ha on plots plowed in 20—30 cm depth.
Water drained earlier from the soils of the deep plowed plots in the
spring and after rainfall in the summer. The difference can be seen
in fig. 1.
No significant difference is between the yields on the harrowed
plots and the plots that were tilled with a rotatiller.
The soil-pores seemed to be smaller but to increase in number in
the plots tilled with rotatiller.
The pot experiment showed that the soils was most fertile in the
first 25 centimeters to the surface. but the fertility decreased with more
depth. The difference in fertility could he evened out by fertilizers in
the first summer.
The surface of the deep plowed field had tendency to become un-
even.