PRONOVA Stelzner EC 2000, Technical Instructions

Page: 31 / 158

33
GB
Reactions of the soil to different pH values
The thinner the wedge, the stronger are the
nutrients bound in the soil, i.e. the smaller is
the possibility for plants to exploit them. Nu-
trients can be taken up quite well in soil that
ranges from slightly acidic up to neutral pH
values (pH 6.5 to 7.0); this capacity declines
the more acidic or the more alkaline the soil
becomes (see Fig. 2).
Figure 2
pH value of the soil and availability of plant
nutrients
For advisory purposes, the pH value of the
soil is often measured in potassium chloride
extracts. Values obtained in this way do not
correspond to the actual pH value, but they
are subject to small fluctuations. This value
is called pH (KCl).
In analyses, you have to consider which pH
value is mentioned, as the differences may
be enormous. Fig. 1 shows the quality of
these differences; it may also be used for
converting pH (KCl) values into pH (H2O)
values and vice versa.
Figure 1
comparison of pH (H
2
O) and pH (KCl)
pH AGRAR 2000