Cover crops can be integral to a vegetable grower’s production cycle for a number of reasons, including soil erosion reduction, weed control, and more. A new research project backed by USDA’s National Institute of Food and Agriculture (NIFA) aims to dig a little deeper by quantifying the nitrogen cycling benefits of cover crops across different organic vegetable production systems in Florida.

The three-year study, led by an interdisciplinary research team from the University of Florida, is powered by a $496,271 grant as part of NIFA’s Organic Agriculture Research and Extension Initiative.

According to Gabriel Maltais-Landry, an Assistant Professor in the UF/IFAS Soil and Water Sciences Department and principal investigator on the project, the overall goal is to optimize the management of cover crops in organic vegetable systems. “We hope to provide fertility to the crop and to the soil, without oversupplying nitrogen, which can become an environmental hazard,” he said. “We also want to be sure that by optimizing the system for nitrogen, we minimize negative trade-offs with other properties, whether that’s crop quality, nematode pressure, or soil health.”

Three specialty crops that represent the diversity of vegetables grown in Florida will be used for the study: bok choy, cucumber, and bell pepper. Maltais-Landry points out that each have different nitrogen demand and growth forms. The plantings will all be conducted in a certified organic field at the UF/IFAS Plant Science Research and Education Unit in Citra.

Sunn hemp will be the main cover crop used. Grasses are another common type of cover crop, Maltais-Landry explains, but grasses don’t break down as quickly as legumes and some are even known to tie up nitrogen during their slow decomposition.

“We’ll be looking at sunn hemp grown alone or in combination with other cover crops to see if mixtures could extend the duration of nitrogen release during cover crop decomposition. We’ll be looking into how much of that nitrogen actually goes to the next crop.

“We’ll also compare nutrient management approaches: one that’s based on composted manure because that’s often what farmers rely on primarily, just for the sake of cost; as well as a more integrated approach that uses different fertility sources.”

Maltais-Landry will be joined on the project by UF/IFAS colleagues Chris Wilson, Sarah Strauss, Zane Grabau, and Xin Zhao.