Sweetpotato and Cover Crops

January 19, 2021
Wanna Kaluwasha discovered some benefits of incorporating cover crops in sweet potatoes.

When Waana Kaluwasha was just a child, she decided she was going to grow up and help small-scale farmers. 

“I come from Zambia, a country in Southern Africa where agriculture employs more than 85% of the population, with the majority being small holder farmers who are faced with various challenges,” said Kaluwasha. 

Kaluwasha got an undergraduate degree in agricultural sciences at the University of Zambia before beginning her Master’s degree at the University of Missouri in 2015. Organic sweetpotato production sparked her interest because sweetpotatoes are an important crop worldwide, and she was curious about whether cover crops could benefit organic sweetpotato production.

“Organic sweetpotato growers are challenged by sustainable soil management, which impacts the occurrence of soilborne disease, weed competition, and other pest issues that reduce storage root yield and/or quality,” said Kaluwasha. “Being organic, their options are limited for pest control.”

With support from a $11,956 SARE Graduate Student grant, Kaluwasha worked on a strategy for using cover crops in organic sweetpotato production. She teamed up with Jim Thomas from Share-Life Farms, a central Missouri farm that has been certified organic since 2004. Overall, they determined incorporating cover crops as green manure before transplanting sweetpotato slips resulted in decreased weeds, healthier sweetpotato plants, and ultimately 1.5 to 2.4-times marketable root yield compared to plots without cover crops. Together, they discovered:

  • Cover crop varieties: both cereal rye and rapeseed can be cover crops in organic sweetpotatoes, where weed control practices are minimally implemented; cereal rye appeared to promote storage root production more so than rapeseed after tillage.
  • Managing weeds: tilling cover crops into the soil suppressed weeds during the early growing season, resulting in dependable and elevated root yield.

“It was a rewarding experience working with farmers and a huge learning experience for both my advisor and I, as this was our first time working with cover crops as relating to organic sweetpotato production,” said Kaluwasha. “I learned so much interacting with Mr. Jim Thomas regarding organic production, it was good to see things from the farmer’s perspective.”

Dig Deeper

Read a full case report about this project.

Watch Kaluwasha talk about her findings.

Want more information? See the related SARE grants: