June 2022
SPECIAL
12
Text: Arno Engels
THE WAY POTTING SOIL DEVELOPS FROM PEAT For decades, peat has been the most important raw material for potting soil, but in recent years, the use of alternatives
also decided to check the quality. This
example. And whatever raw material is mixed, it requires an adjustment in fertilisation and irrigation.
Potgronden, abbreviated to the RHP
has also increased. Potting soil manufacturers participating in GrootGroenPlus are now focusing more on wood fibre, for
Even before potting soil even existed,
later, in 1913, Klasmann in Germany set
grown in a substrate of low moorland.
cultivation, peat was already popular
extraction in 1920 between Groningen
van Nierop van Klasmann-Deilmann,
prior to the potting and container
among users. As fuel, which had been
discovered centuries ago. Peatlands that were not suitable for agriculture due to the wetness were excavated, the peat was laid to dry until it could be use to
start up a fire. The excavations created the Reeuwijkse Plassen, for example.
The peatlands in the Boskoop area have always remained unspoiled, allowing
the tree and ornamental cultivation to
flourish. Peat also proved to be excellent for cultivation. It can quickly absorb
moisture, and it also retains it for a long time.
Several of today’s potting soil
manufacturers have started out with
peat extraction for energy supply. For example, Pindstrup Mosebrug was
founded in Denmark in 1905. Some years
up a peat factory. Deilmann began peat and Oldenburg, and later on the two
merged to form Klasmann-Deilmann.
The transition from peat for firing, to peat for use as a growing medium, began
after the Second World War. Back then,
horticulture had to grow as an industry, to be able to feed the population. This was for example when the first large-scale tomato cultivation started. They were
“But they soon discovered,” says Fons
“that the quality of low moorland wasn’t
the same everywhere and could contain pathogens. Then they switched to a clearer high moorland.
The varying quality was also the reason for setting up a quality control system for potting soil. The testing station in Naaldwijk suggested this, and after
that, the testing station in Aalsmeer
On behalf of trade fair GrootGroenPlus: David Bömer, chairman.
resulted in the national Regeling Handels (regulations on trading in potting soil). For decades, peat was the main raw
material for potting soil. The increasing
demand from the potting and container cultivation also resulted in an increase in production areas. Over the years, Pindstrup began to extract more
peat outside of Denmark, from other
Scandinavian countries, Germany, Ireland and later also from the Baltic States.
The extraction of Danish peat decreased. “That extraction had always been
limited”, says Feico van der Schaaf of
Pindstrup. “It became even more limited
when green parties wanted to protect the peatlands and the government bought off permits. Something that happened
in Germany as well. There was a reason
“Phasing out peat in potting soil brings along new questions. It is great that
we moved to the Baltic states.” It’s not
together. The conversation that is held on the trade fair floor, is of great value for
in Latvia, Estonia and Lithuania, but the
suppliers and growers share their experiences and are trying to find solutions
just that there is more peat available
that.”
climate is also different, according to
Van Nierop. “Baltic peat does not need to
Peat alternatives make fertilisation even more challenging Fertilisation of potting and container
cultivation process.”
we’ve been used to for years: mainly
means that the potting soil can retain
because the quality of the irrigation
nutrients. A manufacturer can measure
The pH of peat alternatives is also
buffer. You are moving in the direction of
cultivation has always been customised, water, the crop and the nutritional requirements can differ for every
company. That already was a big challenge. Developments in the
potting soil have only made this more complicated. “In fact,” argues Lowie
Weerts of Haifa North West Europe, “if we cannot coordinate this well with
the potting soil producer, this might
have negative consequences for the
Peat substitutes in potting soil release this according to Weerts, so he knows how to adjust the fertiliser to this. For
example, wood fibre and bark extract nitrogen from the potting soil during digestion and release manganese
during cultivation. And compost releases potassium. “You have to know all that,”
says Weerts. “It allows us to help think of a fertilisation strategy that works for the grower. This will be different than what
peat dominated potting soil.”
higher than that of peat. As a result,
less calcification is required to achieve the desired pH of the mixture. “But less calcification means less calcium and magnesium for the plants.”
According to Weerts, growers are only partly aware of the effect of using a
peat alternative in the potting soil. “They might know that al alternative retains
less moisture, for example. But this also
fewer fertilisers. That limits the nutritients rock wool cultivation.”
Wood fibre is similar to peat in terms of various properties, but the buffer
capacity of wood fibre is smaller. The
smaller the buffer, the more fluctuations you can get in the potting soil. “And
when it comes to cultivation, similarities and rules are more convenient, since
they will help increase the growth of the crop.”
Schrauwen Machinebouw Zundert
De Ambachten 21, Zundert, Gsm: +31 (0)6 51 835 957 E-mail: info@s-m-z.nl, Internet: www.s-m-z.nl
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