Cover Crop Challenge lets students compete and grow

April 17, 2025

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By Krisy Gashler

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Campus Area Farms
Cornell University Agricultural Experiment Station
School of Integrative Plant Science
Soil and Crop Sciences Section
Agriculture

Cornell AES manages farms and greenhouses that support research but are also unique teaching resources for over 40 courses. This is the sixth story in a series about on-farm teaching; in Cover Crops in Agroecosystems, students explore the uses of cover crops and assess their benefits.

How better to learn with classmates than to soil your undies together? Students in the Cover Crops in Agroecosystems (PLSCI 4125) course learn about the importance of soil nutrient cycling by, among other things, burying a new pair of cotton underwear at the beginning of the semester, then pulling it out at the end to see how much it’s decomposed.

“If you pull the undies out and they’re filled with holes, what you’re seeing is the benefit of our beautiful microorganisms in the soil performing nutrient cycling and all the other ecosystem services that these little guys provide,” said Nazir Adam Sharifi ’24. Sharifi took PLSCI 4125 in Fall 2023 and is now a graduate student in the lab of Matthew Ryan, associate professor in the School of Integrative Plant Science, Soil and Crop Sciences Section.

Ryan teaches Cover Crops in Agroecosystems, in which students learn about the benefits and logistics of planting cover crops, like legumes and grasses, in between cash crop plantings. The practice sequesters carbon dioxide, improves long-term soil fertility and reduces soil erosion – especially important as the changing climate increases the frequency and intensity of extreme rainfall events.

“Cover crops are one of the primary ways that farmers can increase the sustainability of their cropping systems,” Ryan said. “This conservation practice offers ecological benefits, like supporting beneficial insects and reducing water pollution, and it often results in higher yields over time for farmers because of improved soil health.”

Students working with plants in a greenhouse facility — Students in Matt Ryan's class are sampling biomass from their cover crop mixtures in a Cornell AES greenhouse facility on campus. Photo: Matt Ryan

The class is one of over 40 that enrich student learning by hosting experiential activities at the research farms and greenhouses managed by the Cornell University Agricultural Experiment Station (Cornell AES).

One of Ryan’s most impactful activities is the “Cover Crop Challenge.” Students get to choose from among 12 different species, such as crimson clover, annual ryegrass, mustard and oats, to create their own cover crop mixtures. They then plant their mixtures indoors, in one of the Cornell AES greenhouse facilities, and outdoors, in the Crops Garden at Campus Area Farms. Eight weeks later, students take a host of measurements to assess the effectiveness of their cover crops – insect and floral diversity, total biomass, weed suppression and more – and they calculate the economic efficiency of their mixtures.

A student with a big radish — Jake Perno, a student in PLSCI 4125, holds a tillage radish from his cover crop mixture in the Crops Garden at Campus Area Farms. Photo: Matt Ryan

Roots in soil — Crimson clover roots with nodules where symbiotic rhizobia bacteria fix atmospheric nitrogen. Photo: Matt Ryan

Students in a field collecting samples — Students in Matt Ryan's class are busy collecting samples from the cover crop mixtures they designed and planted for the Cover Crop Challenge. Photo: Matt Ryan

Ryan developed the Cover Crop Challenge as a teaching activity in 2013 for his class Sustainable Agriculture: Food, Farming, and the Future (PLSCI 1900), which will be offered again in fall 2025. Between 2021-2023, Ryan worked with colleagues at universities across the country to teach a multi-institutional course Cover Crops in Agroecosystems (PLSCI 4125/6125), which included the Cover Crop Challenge. Students from Cornell, Clemson University, Michigan State University, University of Nebraska–Lincoln, University of New Hampshire and University of Kentucky competed against each other to grow cover crops that were the biggest and most economical. A Dec. 2024 journal article about the Cover Crop Challenge, co-authored by Ryan and 10 colleagues, explores the benefits of the learning activity and offers a guide for others interested in using it.

Students with plants in greenhouse facility — Natasha Djuric (left) and Erika Filer Everest (right) are testing their cover crop mixtures that were grown in a Cornell AES greenhouse.

Natasha Djuric, a graduate student in Ryan’s lab, took PLSCI 4125 in Fall 2022 and co-authored the new article.

“The most impactful thing for me was learning what different people choose to prioritize,” Djuric said. Some students were most concerned with carbon sequestration or preventing soil erosion, while Djuric’s top priority was growing the most flowers to feed pollinators. Students from farming families often prioritized oats, because they knew they were cheap to plant and would grow quickly, she said.

“What we prioritize is a really big factor in deciding which cover crops to use, or whether to use cover crops at all,” she said. “In trying to promote cover crop adoption, it’s really important to see other people’s perspectives.”

For Sharifi, the course brought together complementary elements of key challenges he wants to help address: climate change and agricultural sustainability.

“I came into Cornell focused on the environment and sustainability, but I fell in love with ag, in part because I realized how important ag is for sustainability,” he said. “We have a growing population of 8 billion people, and we need to address problems like climate change and herbicide resistance – modern ag is facing an onslaught of these problems. We haven’t seen a revolution in agriculture since the Green Revolution, and we’re due for another one. I want to be part of that.”

Krisy Gashler is a freelance writer for the Cornell University Agricultural Experiment Station (Cornell AES)

Cover Crop Challenge lets students compete and grow

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