KNOXVILLE, Tenn. — Growers
throughout the nation are setting their sights on spring and the coming 2015
crop, but many of them — especially those who raise specialty fruit and
vegetable crops like tomatoes, strawberries and pumpkins — struggle with the
problem of disposing of the plastic mulches they use to produce their crops.
Mulching with plastic
materials is standard practice for specialty crop growers throughout the U.S.
and the world. The plastic forms a barrier in the field that reduces weeds,
conserves water, and protects soil from erosion. Unfortunately, after their use
in the field, which is typically a single growing season, no good alternatives
exist for their disposal. What is more, retrieving conventional plastic mulches
from the field is laborious and expensive. Once retrieved, they are often stockpiled
on farms or burned, illegally. To add to the problem, any residual plastic left
in the field persists in the environment and can negatively affect wildlife,
soils and water quality.
The absence of an effective
strategy for disposing of conventional plastic mulches threatens the
profitability and sustainability of both large and small specialty crop farms.
To address the problem, a team
of 22 experts with research and extension appointments at the University of
Tennessee Institute of Agriculture (UTIA), Washington State University (WSU),
and Montana State University (MSU) secured a $1.9 million grant from USDA to
study the performance and adoptability of biodegradable plastic mulches (BDMs)
for sustainable specialty crop production. Douglas Hayes, a polymer scientist with
UTIA’s Department of Biosystems Engineering and Soil Science (BESS), will lead
the two-year project, with the assistance of co-project directors Annette
Wszelaki, a UT Extension vegetable production specialist with the Department of
Plant Sciences, and Jennifer DeBruyn, a soil microbiologist, also with BESS.
The team also includes an advisory committee of experts in relevant scientific
fields and government regulations, plastic mulch manufacturers, and specialty
crop growers. Near Knoxville, Techmer PM,
a company in Clinton, Tenn. — which was a stop during President Obama and
Vice-President Biden’s recent visit — is making an “in-kind” contribution to
the project by compounding a blend of specialized biopolymers to produce an
experimental BDM to be included in the research.
UTIA’s East Tennessee AgResearch and Education Center Plant Science Unit in
Knoxville will serve as the site for field studies in Tennessee. WSU’s Mount
Vernon Research Center will serve as a second site, offering different climate
and soil conditions.
The initial effort is expected to take two years, but there is the possibility
of $3 million of additional work that would extend the effort over five years for
a total of nearly $5 million. As planting season approaches, the team, which
also includes UTIA researchers in agricultural resources, rural economics and UTIA’s
Human Dimensions Lab, is gearing up for action.
It’s a complicated problem that has to be solved with the help of scientists
from several disciplines, says Hayes. He explains that while BDMs have been available
as a substitute for conventional plastic mulches for more than 30 years, growers
have been slow to incorporate them into their operations. “Specifically, the
high cost of using BDMs, a lack of knowledge about how they might benefit
long-term sustainability and their unpredictable breakdown have all contributed
to their limited adoption,” he said.
Wszelaki explained that many BDMs that were commercially
marketed as “biodegradable” have not performed up to expectations.
“Biodegradable mulches are supposed to provide the same benefits as
conventional plastic mulches as well as the added benefit of being 100 percent
biodegradable, either in the field or soil or in composting without formulating
toxic residues,” she said. “Many have not been breaking down completely in the
field, even over two years,” she said. “Examining the breakdown products of the
BDMs and their fate in the soil over a five-year period is extremely important
for organic and conventional production alike, as the standard practice of
using plastic mulch for the production of many commercial vegetable crops poses
a costly disposal issue.”
This project will examine the use and
breakdown of five BDMs, and their effects on the soil ecology and crop
production, as well as barriers to adoption of this technology and an
assessment of the impact of these mulches on the environment throughout their
life cycle.
Hayes
says the long-term effort should identify the bridges and barriers to crop
producers’ adoption of BDMs. It’s a stair-step effect, he said. “Understanding
the barriers to adoption should help lead us to the development of best
practices for BDM deployment and disposal. This, in turn, should lead to
increased use of BDMs by stakeholders, which will then be followed by economic
and environmental benefits for growers and consumers,” Hayes said.
Among the consumer benefits are a plentiful supply of healthy fruits and
vegetables and rural landscapes devoid of degrading mounds of discarded plastic
mulch.
The UT Institute of
Agriculture provides instruction, research and outreach through the UT College
of Agricultural Sciences and Natural Resources, the UT College of Veterinary Medicine,
UT AgResearch, including its system of 10 research and education centers, and
UT Extension offices in every county in the state.
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Contact:
Patricia McDaniels, UTIA Marketing and
Communications, 615-835-4570, pmcdaniels@tennessee.edu
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USDA List of Funded Projects:
Performance and Adoptability of Biodegradable Plastic Mulch for Sustainable Specialty Crop Production