Black Walnut Hulls: Turning Trash into Treasure

Chris Chmiel is reinventing compost at his Albany, OH farm, Integration Acres Ltd.

Although Chmiel is widely known for his involvement in the Ohio Pawpaw Festival, through the help of a grant from the Sustainable Agriculture Research and Education program (SARE), he has begun research on composting black walnut hulls for his SARE project “Black Walnut Hulls: Turning Trash into Treasure” trying to discover how useful they can be in compost, despite their bad rap.

“Almost every backyard home gardener has heard of the allelopathic effects of the black walnut tree,” said Chmiel. 

“It seems to be a part of the local folklore. What this means is that whatever successful applications are developed, sophisticated and educational marketing tools will be needed.” Allelopathy refers to the harmful effects that one plant has on another plant. 

With five piles of composting black walnut hulls, Chmiel concluded that he could make a profit from the waste. “I had a lot of black walnut hulls lying around and I’ve learned that turning ‘waste’ products into something valuable has been a key to my business’ financial success. I also knew that this is a type of ‘black gold’ worth something,” explained Chmiel.

“I figured that the utilization of free local resources like the shredded leaves, wood chips and barn bedding is a good and realistic model for my self and other farmers interested in sustainability,” said Chmiel.

Chmiel has seen success in his own pawpaw patches with the black walnut hulls. He had some straight, two-year-old black walnut hull compost left from 2003. He then spread some of it in pawpaw patches as light mulch. It appeared to break down nicely in the soil, contributing organic matter. He reported that fruit production in these patches seems to be stable or improving.

“I’ve seen local growers and landscapers starting to use and appreciate this valuable natural resource.  I think the most interesting thing to the people using the product is that the pH is 7.3 and the organic matter content is 79%.  Most people assume it is an acidic product and are surprised that it is a sweet product.”

Hank Huggins, a local native plant and gardening enthusiast has experienced success as well.

“Hank tried a truck load of the 2003 composted black walnut hulls. He mixed it into beds for raspberries. He says they’re alive and will see how they produce in the coming year,” said Chmiel.

“I think this is a great way for walnut hullers around the country to maximize their on farm resources while providing a local, natural product that should be quite cost competitive to alternative sources. I knew that the SARE guidelines would apply well to this project, and that other walnut hulling operations around the country could benefit from some of this research,” said Chmiel.

Since 1988, the Sustainable Agriculture Research and Education (SARE) program has helped advance farming systems that are profitable, environmentally sound and good for communities through a nationwide research and education grants program. The program, part of USDA’s Cooperative State Research, Education, and Extension Service, funds projects and conducts outreach designed to improve agricultural systems.

Want more information? See the related SARE grant(s) FNC01-371, Using Animals to Manage Pawpaw Patches.