PRONOVA Stelzner EC 2000, Technical Instructions

Page: 46 / 158

48
GB
6. Tables
6.1 Scale for soil activity:
Activity, g/litre Grouping
of values
Plant absorption for elements with
a) High fb value
(N,CI,S)
b) Mid-level fb value
(K, Na, Ca, Mg, B, Mo)
c) Low fb value
(P, Fe, Mn, Zn, Cu, Al)
0,00 – 0,05 very minimal insufficient obstructed very obstructed
0,05 – 0,10 minimal moderate too low insufficient
0,10 – 0,20 moderate sufficient moderate still too low
0,20 – 0,40 mid-level good sufficient moderate
0,40 – 0,80 high good good good
0,80 – 1,20 very high very good very good very good
1,20 – 1,40 critically high too strong inharmonious inharmonious
> 1,40 damaging
leads to visual da-
mage, toxic range
For sixty years we have known that it is not
the quantity of dissolved salt but the salt
activity which effects chemical reactions
and physical processes. That also applies
without restrictions to nutrient absorption by
plants.
So now when we wish to understand the
nutrient potential, it is important to determine
not the quantity of dissolved elements in the
soil but the activity of these elements.
6.2 Characteristics of quality-assured culture substrata (RAL-GZ 252, 2006) - Permissible substrata-
source and inert materials of assured quality or equivalent products
Quality feature Permitted value range
Fine composition
Quantity of oversized particles > 10 mm
Maximum 5 vol.-% incl. fibres
Average composition
Quantity of oversized particles > 20 mm
Maximum 5 vol.-% without fibres
Coarse composition
Quantity of oversized particles > 40 mm
Maximum 10 vol.-% without fibres
pH (CaCl
2
), overall 5.0 to 6.5
pH (CaC
2
) for azaleas, ericas, boggy soil 3.4 to 4.6
Salt content (as KCl), overall < 3.0 g/l
Salt content (as KCl) for azaleas, ericas, boggy
soil
< 1.0 g/l