Emerging farmers apply science, explore soil-improving crops

Horticultural science professor Julie Grossman near cover crops at Big River Farms.
November 5, 2020

Big River Farms and UMN partner on summer cover crops to benefit the environment, increase profitability for underrepresented farmers

The story of how Big River Farms and the University of Minnesota are working together to improve soil health, pollinator habitat and landscape cover has a number of intriguing “plots” — all of them centered on cover crops and intended to make the science of environmentally-friendly farming accessible and beneficial to emerging farmers.

Big River Farms, a program of The Food Group, is a non-profit 150-acre incubator farm near Marine on St. Croix, Minnesota. Focused on using nutritious food to strengthen community, it offers education in organic agriculture to farmers who have historically been discriminated against in the food and farming system, such as BIPOC, Latinx, women and New American farmers.

These emerging farmers represent a growing population of food producers in Minnesota and the upper Midwest. At Big River Farms, farmers share infrastructure and equipment and receive mentorship and education as they start their own farming businesses.

For a number of years, Big River Farms has partnered with Julie Grossman, PhD, and her team at the University of Minnesota on workshops and demo plots, using science to enhance soil quality, improve nutrient management and increase productivity on the land. Grossman is an associate professor in the Department of Horticultural Science at UMN’s College of Food, Agricultural and Natural Resource Sciences (CFANS) and Principal Investigator at the Grossman Lab, which optimizes legume management to provide non-legume crops with nitrogen and improve soil health and function, especially in organic systems.

A summer under “cover”

In summer 2020, farmers at Big River Farms collaborated with Grossman’s team to plant plots with summer cover crops, such as legumes and grasses. Cover cropping — which in this case means planting between cycles of main crops — is a management practice used to contribute to soil health and a variety of other benefits on working land.

“Cover crops have multiple benefits,” said Grossman. “For example, many organic farmers are interested in nitrogen fixation, meaning the chemical process by which nitrogen in the atmosphere is assimilated into organic compounds.”

Grossman explains that legume cover crops, including peas, vetch and crimson clover, are essentially a free form of fertilizer. “Even though these particular cover crops aren’t harvested for food or feed, they take nitrogen from the air in association with soil microbes, capture it in their leaves, and then it goes back to the soil as fertilizer when it is time to ‘kill’ the cover crops,” she said, describing the process of using a walk-behind tractor to chop the cover crops into tiny pieces that are highly accessible to microbes in the soil. 

“Working with the Grossman Lab has helped make the practice of cover cropping much more approachable,” said Molly Schaus, farm director at Big River Farms at the time. “The research done this summer was particularly interesting to me because it studied the benefits of combining a partial season cover crop rotation with either an early or late season vegetable crop. This means we could learn to incorporate cover crops within a vegetable rotation, rather than taking a piece of land out of production for an entire season to gain a benefit from the cover crop.” 

Schaus noted that Grossman’s team really focused on making the science applicable to the farmers. “The research they conducted is in a real farm setting, and they focus on studying practices that are actually realistic for farmers to implement.”

Attracting pollinators 

One of the most immediate impacts Schaus noticed from having flowering cover crops was an increase in pollinators. Naomy Candelaria, an MS student in the applied plant science program at CFANS and a CFANS Diversity Fellow advised by Grossman and Mary Rogers, PhD, in Horticultural Science, spent much of her summer at Big River Farms studying the capacity of cover crops to provide ecosystem services, including attracting beneficial insects and pollinators.

Grossman smiled as she described some of Candelaria’s work at a few sites: “vacuuming up bugs” from fields in order to study them. According to Candelaria, the best part of the project — in addition to being surrounded by beautiful flowering plants and mesmerizing insects — is the cross-disciplinary work. “Having the opportunity to acquire diversified knowledge and participate in different field or lab activities is always entertaining and captures my attention,” she said. “And as a future-generation farmer myself, I need to be aware of all the essential components that make up the farm, including soil and entomological interactions.”  

Nitrogen knowledge 

For Madison Moses, a PhD student in applied plant sciences and DOVE and CFANS Diversity Fellow working on the same project, the summer was all about testing which cover crops perform best at different times, such as “after spring greens” and “before fall broccoli.” 

“We’re particularly interested in trade-offs between nitrogen provision and pollinator benefits in cover crops,” said Moses. “It has been exciting to see the differences in growth patterns between some of the cover crops we’re using. For example, legumes like field pea and cowpea seem to grow much slower, especially in the first month of growth, than non-legumes like sorghum-sudangrass or buckwheat. This tells me that the non-legumes, while impressively fast growing, probably have low tissue quality that can become a barrier to nitrogen provision.”

For Moses, their favorite part of the project was using a water wheel transplanter for the first time. “I had just started grad school shortly before our planting date for lettuce at Big River Farms, so it was one of my first field days here in Minnesota,” they said. “The water wheel transplanter moved very fast, so I was stressed about it at first. But once I got the hang of it, I really enjoyed it. I have never had a transplanting go so quickly or smoothly.” 

Sowing relationships, reaping rewards

For Grossman, the most satisfying aspect of partnering with Big River Farms is the opportunity to work alongside farmers to answer questions and help them maximize productivity. “The teamwork is very important to the growers and to us,” she said. “The ingredients to success — collaboration, trust and long-term relationship building — have yielded great results.” 

Schaus agrees. “The members of Julie’s lab have been excellent and eager teachers, which improves our community’s cover crop techniques and practices.” 

For emerging farmers at Big River, Grossman Labs and CFANS graduate students, it’s clear the scientific “plots” will continue to thicken and open new chapters of opportunity with cover crops.

Learn more about the CFANS Diversity Fellowship program for graduate students and postdocs

Please visit this page for more information on the University’s DOVE Fellowship