RALEIGH, N.C. – Researchers at North Carolina State University have developed a new, non-toxic solid lubricant for farm equipment used for seed dispersal.

Typically, solid lubricants are used to prevent seeds from sticking together or clumping, which can jam machinery used to plant seeds. However, commercially available lubricants contain ingredients that can be toxic to farmers, farmland and pollinators, including talc and microplastics, said Martin Thuo, professor of materials science and engineering at NC State, said.

Canada banned the use of talc and graphite as seed lubricants for pneumatic planters when planting corn and soybean seed treated with neonicotinoid insecticides because talc and graphite tend to erode the treated seed coating. This means that the dust generated during planting can carry the insecticide off the seed into the air, which could potentially be inhaled or ingested by pollinators and cause their deaths.

While other countries have not formally banned talc as a seed lubricant, there have been movements to ban its use in other industries. For example, talc is anticipated to be banned in 2027 across the European Union after the European Chemicals Agency’s Committee for Risk Assessment classified talc as carcinogenic, mutagenic and reprotoxic. This ban will apply to cosmetics and other products available for consumer consumption.

Talc has been under scrutiny in the U.S. since the Johnson & Johnson lawsuits, which have focused on the risk of asbestos present in talc-based baby powders. However, there have been no specific bans related to talc’s use in food, pharmaceutical or cosmetic products.

Some companies, like Bayer CropScience, have begun to offer alternatives to talc and graphite seed lubricants. However, these alternatives often use plastics, leading to concerns about microplastics, or the tiny plastic particles that persist after the breakdown of larger plastic items. Microplastics are a growing concern among scientists in all fields and are problematic for human and animal health, as well as having detrimental impacts on the environment.

“It is unfortunate that current products are threatening our food supply. While Canada and (the) EU are taking steps to protect farmers, it is my hope that the U.S. and other large mechanized (agriculture) economies like Brazil and Australia will ban these materials before it’s too late,” Thuo said.

Thuo and his research group set out to make a safer seed lubricant alternative. First, the research group explored talc-like compounds, but found that while these compounds made good lubricants, they were expensive for farmers. The group then began exploring cellulose, an abundant compound most known for being the structural component of the cell walls of green plants. The team was able to create a lubricant derived from cellulose, made up of millions of tiny fibers. The surface is grafted with hydrophobic particles that repel water.

“Scientifically, we would call (the lubricant) a network disruptor. It (interferes) with how forces move within a bed of particles to avoid convergence (jamming or clustering),” Thuo explained. “By disrupting the nature of seed-to-seed contact, being able to absorb moisture, and the ability to remove any surface charges, allows these materials to disrupt force distribution in a collection of seeds as they move down the planter.”

In other words, the lubricant works because it reduces the friction that happens when seeds rub against each other, because the cellulose fibers are smoother than the surface of the seeds. The fibers are even more slippery because the hydrophobic particles on the cellulose fibers repel the absorbed water on the surface of the seeds.

Thuo and his research team tested the material over hundreds of acres across several years through blind testing with farmers.

“We found that we get very high efficiency in planting, and the yield of the crops is comparable to that of talc or microplastic fluency agents,” Thuo said.

Additionally, the group found that very little of the seed coating is eroded when using the cellulose-based lubricant. This means that the dust produced during planting is less likely to contain pesticides that can be harmful to pollinators, birds and farmers.

“We are working with some of the leading ag companies to see how to best get this to market,” Thuo added.