Weeds. Not only do they strangle your aunt’s petunias at the roots, they also have the entire agricultural industry in a $33 billion headlock.

That is the estimated annual cost of dealing with invasive plants that compete with cultivated crops for water, nutrients, light, and space.

These days, mulch films are widely used in agriculture to suppress these pesky plants, retain soil moisture, and regulate soil temperature, thereby enhancing crop yields. However, conventional plastic mulch films pose severe environmental issues, as they do not decompose and thus contribute mightily to our planet’s plastic pollution.

Jonas Baltrusaitis, an associate professor in the Department of Chemical and Biomolecular Engineering at Lehigh University, is at the forefront of developing sustainable nutrient-delivery materials, including composite nutrient-containing degradable polymers for mulch films. His pioneering work in this area aims to create sustainable alternatives to traditional plastic mulch films, addressing significant environmental challenges in agriculture.

Recently, this work has earned the support of the United States Department of Agriculture (USDA) and its National Institute of Food and Agriculture through a new multi-year research grant entitled PARTNERSHIP: Engineering Nutrient-Enhanced Mulch Film to Improve Degradation and Soil Health. The $744,000 project, which formally kicked off July 1, 2024, runs through June 30, 2028. Baltrusaitis, the lead researcher, is teaming up with colleagues from the University of Massachusetts Lowell; USDA Agricultural Research Service (ARS) in Maricopa, Arizona; and Ben Gurion University in Israel, who are contributing diverse and critical expertise to the project.

A farmer’s dream

Baltrusaitis’ research is focused on creating sustainable nutrient delivery systems by incorporating them into biodegradable polymers that can perform the same functions as traditional plastics, with an ecologically inspired twist. The films would break down naturally and safely, while adding nutrients to the soil to benefit crops.

Baltrusaitis’ team employs a multidisciplinary approach, combining expertise in sustainable chemical engineering and materials design, environmental engineering, and agricultural practices. They are designing nitrogen-efficient materials, urea cocrystals, to provide nutrients to the mulch films.

The team is collaborating with Margaret Sobkowicz-Kline, a professor in the Plastics Engineering Department at UMass Lowell, leveraging her work with biopolymers such as polylactic acid (PLA) and polyhydroxyalkanoates (PHA), which are derived from renewable resources and can decompose into nontoxic components under specific environmental conditions. Sobkowicz-Kline will combine the cocrystals with commercial bioplastics that are already suited for degradation in soil conditions, but which have unknown impacts on the longer-term soil health. Her team will create films with these bioplastic-cocrystal compounds for testing in laboratory and real agricultural environments.

“Our work with urea cocrystals that provide a convenient vehicle of nutrient delivery into degradable polymers aims to develop sustainable solutions for agricultural practices,” Baltrusaitis explains. “Traditional plastic mulch films have a detrimental impact on the environment. By developing biodegradable alternatives, we can help reduce plastic pollution, improve soil health, and promote sustainable farming practices.”

One of the key challenges Baltrusaitis and his team face is ensuring that the biodegradable mulch films maintain their structural integrity and effectiveness throughout the growing season. To address this, they are investigating various formulations and processing techniques to enhance the durability and performance of the bioplastics. This involves rigorous testing under different soil and climate conditions to ensure that the films meet the practical needs of farmers while decomposing effectively after use.

“We are constantly refining our formulations to strike the right balance between durability and biodegradability,” he says. “It’s crucial that the films remain effective throughout the crop cycle and then degrade without leaving harmful residues. This requires a deep understanding of both material science and agricultural needs.”

In addition to the technical aspects, Baltrusaitis is also focused on the economic viability of biodegradable mulch films. Traditional plastic films are relatively inexpensive, and transitioning to biodegradable alternatives must be cost-effective for widespread adoption. His team is working on optimizing production processes and sourcing sustainable raw materials to make the biodegradable films competitive in the market.

Baltrusaitis emphasizes the broader implications of his research. “Sustainability in agriculture is not just about protecting the environment; it’s also about ensuring economic viability for farmers,” he notes. “Our goal is to develop solutions that are affordable and practical, so farmers can adopt them without compromising their livelihoods.”

Baltrusaitis’ work has garnered attention and support from various stakeholders, including environmental groups, agricultural communities, and policymakers. His research aligns with global efforts to promote sustainable agriculture and reduce plastic pollution, making it highly relevant in today’s context of increasing environmental awareness.

Looking ahead, Baltrusaitis is optimistic about the potential impact of his research. “We are making significant strides in developing nutrient-containing biodegradable mulch films that can transform agricultural practices,” he said. “The ultimate success of our work lies in its adoption by farmers and its contribution to a more sustainable agricultural system. I am excited about the future and the positive changes we can bring about to create a more sustainable and resilient future.”