Issue 02/2017

Agriculture/Horticulture
Biodegradable mulch films:
where are we?
Biodegradable mulch films have been commercially
available since the beginning of the 2000s. Throughout
the years, various projects (e.g. EU projects, such as
Bioplastics 2001-2005 and Agrobiofilm 2011-2013) have focused
on their development; they have also been the subject
of many publications. Also, these films are now used by many
growers (see INFO BOX 1) in order to improve the yield and
quality of the crops. Biodegradable mulch films have gained a
place and a role in the world of agricultural plastic (see INFO
BOX 2), especially in the last decade; in fact, roughly 5 % of the
mulch film sold in Europe today (80,000 tonnes/year) is biodegradable.
The films are largely used in Italy, France, Germany, Benelux
and Spain, mainly for vegetable crops.
It has been estimated that almost half of the plastics
worldwide are used for disposable applications [2]. A mulch
film may be considered disposable due to its relatively brief
service life (between 4 and 10 months), after which, at the
end of the cultivation period, it needs to be removed from the
field and disposed of, according to provisions of the European
directives dealing with waste management (directives 99/31
EC, 2000/76 EC, directive 2008/98/EC). In Spain and Italy, no
more than 50 % of this used agricultural plastic is recovered, of
which some 50 % goes to landfill [3]. Recovered mulch film is
generally heavily contaminated with soil, stones and biological
waste (up to 60-80 % of its initial weight), which makes
mechanical recycling difficult [4]. Mulch films that are not
properly be collected tend simply to be left in the environment
(dumped or buried in the soil) or burned on the fields, which
negatively impacts the environment [5].
Biodegradability, as a property, raises interesting possibilities
for an efficient solution to tackle a series of problems
connected to waste management. Biodegradable mulch films
do not need to be removed from the soil, as they are able to
be biodegraded by soil microorganisms (mineralization). The
use of biodegradable mulch films eliminates altogether the
costs of collection and disposal of very dirty and non-profitable
materials and it is fully in line with the EU Strategy on Waste
Management (1989).
Biodegradable mulch films that can be left in the soil after
use must meet the biodegradability and non-ecotoxicity
requirements applicable for this environment. The current
available standards for biodegradable mulch films in Europe
are the French NF U 52 001:2005 and the Italian UNI 11495:2013
standards. The CEN TC 249/WG 7 Committee is preparing a
European Standard on biodegradable mulch films. This will be
a useful tool to provide a shared foundation for the definitions
and requirements for these products. In general, to qualify
as biodegradable according to existing norms and standards,
a biodegradable mulch film should provide a minimum
biodegradation threshold of 90 % (relative to a standard
material) in two years and an ecotoxicology assessment in
soil is required (see INFO BOX 3). The OK Biodegradable Soil
program developed by the Belgium certification body Vinçotte
is the main reference in the European market to clearly
identify a biodegradable mulch film. Nonetheless, some oxo—
degradable or photo-degradable mulch films can be found on
the market, and are used by growers. These films claim to be
biodegradable but do not meet requirements of the available
standards. They are produced from traditional polymers
formulated with specific additives which improve the physical
degradation (fragmentation) of the films. The films break down
into small pieces and fragments, which then persist in the
environment. Appropriate communication measures are still
needed in order to ensure that farmers and other stakeholders
are informed of and understand these differences.
Substantial evidence has been gathered over the past 15
years showing that biodegradable mulches on vegetable crops
behave in the same way functionally as conventional nonbiodegradable
films, from an agronomic and mechanical point
of view.
The use of biodegradable mulches can be also introduced
in crops in which, for various reasons, mulch films have
tended not to be applied. The biodegradability of the materials
becomes a useful agronomical feature in all cases where
traditional mulch films cannot be properly collected from the
field (perennial crops) or the presence of a mulch film would
make specific agronomical operations difficult (processing
tomatoes), or if efficient weed control is difficult to achieve with
traditional strategies in low input techniques (rice).
In some areas of Europe, vineyards are mulched with films
in the first year of cultivation. This improves the development
of the plant (successful and homogeneous growth) and offers
an option for weed control on the row. In Southern France,
biodegradable mulches were shown to be a good alternative
to non-biodegradable ones, in terms of positive effects on
plant growth and on yields (after harvesting at 18 months). On
analyzing the root systems of the mulched and the unmulched
vines, the biodegradable mulches were found to provide
improved root system growth [6].
The two most important European areas for processing
tomatoes (Spain and Italy) have introduced the use of
biodegradable mulches in tomato production. This technique
can reduce the use of herbicides in weed control, improve root
development, offer protection against low temperatures at the
beginning of the crop cycle and, finally, produce higher yields
[7].
Rice is another crop that benefits from the use of
biodegradable mulches. In the last two years, the use of
biodegradable mulches in one of the main European rice
cultivating areas (North West Italy) has demonstrated that
biodegradable mulch films can control weeds and enhance
rice growth, drastically reducing the use of herbicides [8].
The use of biodegradable polymers in well-defined
application areas is definitely an interesting possibility for the
22 bioplastics MAGAZINE [02/17] Vol. 12