soil health

November 20, 2024

Bioplastics may be toxic to soil organisms, study calls for more testing

By Douglas Main

Bioplastics, often considered a safer alternative to synthetic plastics, may in some cases be toxic to soil organisms, a worrisome finding that indicates a need for more thorough testing, according to a new study.

The work adds to a growing body of research suggesting that bioplastics, which are derived from plant materials or other biological feedstocks, are not necessarily safer than plastics that come from petroleum.

The new study, published this month in Environmental Science and Technology, found that two types of bioplastic fibers were more toxic to earthworms than were bits of conventional polyester. While promoted as “environmentally friendly,” the alternative materials actually may be more harmful in some ways than the conventional plastic, the study determined.

“We need more comprehensive testing of these materials before they are used as alternatives to plastics,” said Bangor University researcher Winnie Courtene-Jones, who is lead author of the study.

Bio-based fibers like viscose and lyocell are used in clothing, especially in fast fashion, but also in wet wipes and a range of other products. The study said more than 320,000 metric tons were produced in the textile industry in 2022 and that is expected to continue to climb. When such clothes are washed, they can shed fibers into wastewater. Thousands of tons of sewage sludge are added to farmlands around the world, which can directly transmit such fibers into the soil.

The study authors said they exposed worms to fibers from polyester, as well as viscose and lyocell, which are made from cellulose and used in “natural” fabrics. They found that after three days, 30% of the first group died, while the death toll was 60% for viscose, and 80% for lyocell.

February 28, 2024

New report questions USDA support for certain climate “smart” practices

A new analysis of US Department of Agriculture (USDA) funding for “climate-smart” conservation practices argues that several are unlikely to actually have climate benefits and one may even increase harmful emissions, though government officials say the analysis is deeply flawed and based on “incorrect assumptions.”

With nearly $20 billion from the Inflation Reduction Act (IRA) to be used between 2023 and 2026, the USDA is investing more money than ever in combating greenhouse gas emissions from agriculture, which makes up 10% of US emissions, according to the EPA.

The analysis from the Environmental Working Group (EWG), a nonprofit environmental research and advocacy organization examines elements of the USDA’s Environmental Quality Incentives Program (EQIP), which provides funding for conservation practices. Congress designated $8.45 billion for EQIP specifically. As part of that, an increasing amount of money is going towards so-called “climate-smart” practices aimed at sequestering carbon in soil or reducing greenhouse gas emissions.

EWG said that USDA is allowing farmers to claim this climate funding for implementing many practices that are unproven to help reduce emissions.

The report alleges, for example, that money can go toward a waste storage facility, used for livestock, would likely increase greenhouse gas emissions, according to the USDA’s own data.

The USDA expanded its “climate-smart” list – the specific practices that are eligible for funding – to allow 15 provisional practices, on which the USDA currently lacks data about their effect on emissions, EWG noted in its report.

USDA Press Secretary Allan Rodriguez called EWG’s analysis “fundamentally flawed, speculative, and rest on incorrect assumptions.”

“Unfortunately, EWG did not take into account the rigorous, science-based methodology used by USDA to determine eligible practices, nor the level of specificity required during the implementation process to ensure the practices’ climate-smart benefits are being maximized,” Rodriguez said in an emailed statement.

The single largest conservation practice funded over the past six years is the use of cover crops, according to EWG, with $505 million (9% of overall funding) going toward the practice. The use of cover crops is widely considered a strongly beneficial practice for soil health and sequestering carbon.

But only one of the other top 10 uses of the money is on the climate-smart list. Six of the new “provisional” practices were also in the top 10.

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February 14, 2024

Pesticide-treated seeds harm earthworms, study finds

By Shannon Kelleher

Commonly used pesticides pose a toxic threat to earthworms, creatures considered crucial for the health of soil used to grow crops, according to a new study published Wednesday.

The study builds on evidence that a class of insecticides called neonicotinoids, or neonics, are harming a range of species important for planetary health. Neonics have been banned in many countries but are popular with farmers in the United States.

The authors of the new study said they found that when earthworms were exposed to four different types of neonics, as well as the fungicide difenoconazole, they suffered damage to their mitochondrial DNA and gained significantly less weight than earthworms not exposed to the chemicals. The pesticides were especially damaging when the worms were exposed to a neonic plus the fungicide in combination.

The findings were published in the journal Environmental Science & Technology Letters.

“We need to re-evaluate the toxicity of neonics and the synergistic effects of neonics and systemic pesticides in those non-target organisms when they are applied to soil simultaneously,” said Chensheng (Alex) Lu, a professor at Southwest University in Chongqing, China and an author of the study.

“The contribution of earthworms to crop yields is as essential as pollination done by honey bees,” he added. “A healthy soil is simply not possible without the presence of earthworms.”