Fresh Market vegetable
growers use plastic mulches to warm the soil, retain soil moisture,
and suppress weeds, often resulting in higher yields and advanced crop
maturity. Presently there are in excess of 4,000 acres of vegetables
grown on plastic mulches in Ontario.
Plastic mulches, however, impact the environment in a negative manner.
They are produced using non-renewable resources, and are often used
only for a single season. Disposal usually involves bringing the material
to a municipal landfill, but with increasing pressure on landfills to
reduce intake levels, these materials may at some point not be allowed.
In Ontario, Canada, municipal landfills are only required to accept
residential waste. Since agriculture plastic is considered an industrial
waste, it could be easily refused. Efforts are underway to recycle this
material. But it is often difficult, due to the dirt and moisture which
accompanies it.
Recent Developments
Recently, biodegradable materials have been developed which have
the potential to be used as agriculture mulches. These products are
available in dark and clear films, and could be used on a range of
vegetable crops.
The products are not like the photodegradable type of mulches which
came apart after exposure to the sun, but rather are degraded by microorganisms
in the soil. They consist mainly of plant starches, and over time,
are supposed to completely degrade in the field, eliminating the need
for pickup and disposal. The main use of this material at the present
time is garbage and grocery bags.
Trials were conducted at two locations in Ontario - Ridgetown and
Harrow - using several types of degradable mulches, which were compared
to production on standard plastic mulch and no mulch. Initially, three
biodegradable mulches were evaluated at Ridgetown in 2001. However,
two of the mulches were brittle and tore within two weeks of being
laid. Only the degradable mulch supplied by Polar Gruppen was evaluated
for yield and fruit characteristics at both locations in 2001.
Fruit characteristics (average weight, wall thickness, length) of
bell pepper (c.v. Boynton Bell) grown on the biodegradable mulch did
not differ from peppers grown on standard plastic or bare soil in
2001.
All mulches improved marketable yields of peppers when compared
to bare soil. Also, yields of peppers grown on the biodegradable mulch
did not differ from those grown on standard black mulch.
In 2001, the degradable Polar Gruppen mulch remained intact until
early august. However, by late august only 50% of the ground was still
covered. In 2002 it appeared to degrade quicker with little mulch
cover remaining by the end of August. A second degradable mulch, which
was evaluated in 2002 and supplied by Recoltech, was more durable
and remained largely intact the entire season.
