Íslenskar landbúnaðarrannsóknir - 01.09.1982, Page 8

6 ÍSLENZKAR LANDBÚNAÐARRANNSÓKNIR
TABLE 1. Cultivation history of the fields, where samples were taken. 1. TAFLA. Ymsar upþljsingar um þá garða, er sýni voru tekin úr.
Area Sample Soil- Years of uninter- Years of uninter- Amount oflinuron
(see fig. 1) (nr) type rupted potato growing rupted herbicide usage used (kg/ha)
Svteði Sýni Jarðvegs- Fj'óldi ára með sam- Fj 'óldi ára með samfelldri Magn linurons
(sjá 1. mynd) (nr.) gerð felldri kart'ófiuriektun notkun illgresiseyðis notað (kg/ha)
monolinuron linuron
I 1 loamy 30 10-12 1.5
I 2 5) 10 7 1.25
I 3 >> 6-8 6 0.75-1.5
I 4 ) 5 40 5 10-12 1.1
I 5 5» 50 8 1.25*
I 6 )5 7-8 6 1.5
I 7 )) 12 3 6 1.25
I 8 >) 17 3 10 0.75-1.25
I 9 )) 15 3 8 1.25
I 10 sandy loam 5 5 1-1.25
I 11 loamy 35 3-4 12 0.75
II 12 sand 15-20 15 0.4
II 13 „ 33 15 <0.5
II 14 sandy loam 30 15 0.75
II 15 )) 5) 25 15 0.75-1.0
II ,. 16-25 sand 30 6-15 0.3-0.5
III 26 loamy 11 11 1.0
III 27 sandy loam 16-17 1 15 0.5
IV 28 loamy 12 12 1.25
IV 29 sand 10 10 0.5
IV 30 )> 15 15 0.75
V 31 sandy loam 10 10 0.35-0.45
V 32 5) )) 10 10 0.35-0.45
* (1979: 12.5 by mistake)
20 °C until analysed. Under these storage
conditions the loss of linuron can be
considered negligible.
Samples of soil were taken in the same
manner from the same fields at the end of
August 1981, before harvesting com-
menced. They were also prepared in the
manner described previously.
Potatoes were taken from under at least
15 plants in each of the test fields at the end
of August 1981. On return to the labora-
tory these were immediately macerated in
a Waring Blender and the macerate stored
at — 20°C until analysed.
Analytical methods
The method of quantitative analysis of
linuron in soil and potato samples was
based on extraction using dichloro-
methane (soils) or acetonitrile (potatoes).
The crude extract was then evaporated to
dryness, redissolved in petroleum ether
and cleaned-up by extraction into
dimethyl sulphoxide, followed by reextrac-