Agriculture Reference
In-Depth Information
materials and other panels or boards, but
not when used for combustion (Schätzl
et al
., 2006).
LLUR, 2012). The UK and Switzerland have
already decided to reduce and eventually
phase out the use of peat entirely in their
countries (Secretary of State for Environ-
ment, Food and Rural Affairs, 2011;
http://
lang=de&msg-id=47174)
. Until now, how-
ever, these decisions have had little effect
on the volume of peat consumed, as envir-
onmentally friendly, economically competi-
tive and high-quality alternatives have been
lacking.
The most promising alternative for peat
as a constituent of growing media is sphag-
num biomass, which has similar physical
and chemical properties as white peat.
Since 2004, peat moss cultivation ('sphag-
num farming') has been studied in green-
house and field experiments by the Univer-
sity of Greifswald (Germany) and associated
research and industrial partners. A com-
mercial scale pilot site of
5
ha was installed
successfully on former bog grassland in
spring 2011 (Joosten
et al
., 2013). Plant cul-
tivation experiments by the Horticulture
Research Station, Hanover and the von Hum-
boldt University, Berlin have shown that
growing media of sphagnum biomass - even
up to a proportion of 100% - enable profes-
sional plant cultivation without loss of
quality compared to peat. Next to providing
a renewable alternative to fossil peat, sphag-
num farming may enable a climate-friendly,
sustainable after-use option for abandoned
cut-over bogs and degraded bog grasslands
Sphagnum farming for horticultural
growing media
The cultivation of vegetables, fruits and
flowers is increasingly soil-less, i.e. takes
place in pre-prepared 'growing media' that
allow uniform, high-quality plants to be
grown at very high productivity levels. Sphag-
num peat has, in the last decades, emerged as
the foremost constituent of these growing
media (Joosten, 1995; Alexander
et al
.,
2008) because of its structural stability, low
bulk density, high porosity and low pH, nu-
trient and nitrogen immobilization levels
(Schmilewski, 2008). Annually, some
30
mil-
lion m
3
of peat in the EU are used for the
production of growing media that support a
modern horticulture, accounting for a turn-
over of €1.3 billion and
11,000
jobs (Alt-
mann, 2008).
The highest-quality peat is slightly
humified sphagnum peat ('white' peat),
which over the past 3000 years has formed
from sphagnum mosses. In most countries
of western and central Europe, including
Germany, the stocks of white peat are nearly
depleted (Joosten, 2012), and raised bogs
are protected as a priority habitat under the
EU Habitat Directive (92/
43/
EEG). To satisfy
horticultural demands, white peat is, in
increasing volumes, imported from Scandi-
navia, Canada and, especially, the Baltic
States (Joosten, 1995). Peat extraction thus
progressively destroys raised bogs with
their typical biodiversity, carbon storage
capacity, water regulation function and pal-
aeo-environmental archive. The white peat
used in Germany, for example, leads to an-
nual emissions of
20
Mt of CO
2
, that is, a
volume similar to that from aviation (
http://
A reduction of these negative environ-
mental effects of horticultural production
needs urgent attention (Verhagen
et al
., 2009;
Benefits of Paludicultures
Compared to land use on drained peat soils,
paludicultures have important environmen-
tal benefits (Wichtmann and Wichmann,
2011a). Rewetting as a precondition for
paludiculture may restore drained peat-
lands to peat-forming ecosystems, enhan-
cing important regulating services such as
climate regulation through protecting car-
bon stores and new carbon sequestration,
water-quality regulation by providing sinks
for nutrients and water filtration (Trepel,
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