UI Extension to study early seeding, optimizing nutrient and water-use efficiency in mustard

An observation a crop scientist made while glancing at a flower bed at the University of Idaho’s Aberdeen Research and Extension Center inspired a trial that could help southern Idaho mustard farmers increase their yields.

It was March of 2025, and the spring planting season was still several weeks away when U of I Idaho Barley Commission Endowed Barley Agronomist Jared Spackman noticed a few volunteer mustard plants had germinated in flower beds behind the research facility.

Based on that discovery, he’s planning mustard trials that will include research into frost seeding — extending the spring growing season by sowing seeds well before the soil is warm enough for germination, putting seeds in a position to sprout at the earliest possible moment.

“This could be an opportunity to get mustard to grow faster and earlier in the spring,” Spackman said. “We will plant mustard after the risk of germinating in the fall is over, and it will theoretically start to germinate as soon as conditions are suitable the following spring.”

Spackman and postdoctoral research scientist Hafiz Haider Ali recently received a two-year, $100,000 award through the U.S. Department of Agriculture Specialty Crop Block Grant (SCBG) Program, administered by the Idaho State Department of Agriculture, to study frost seeding of mustard as well as approaches to optimize nutrient and water-use efficiency for Idaho’s culinary mustard varieties. The Idaho Oilseed Commission submitted the grant application.

Many crops, including canola, have cold-hardy varieties available that can be planted in the fall, germinating before the snow falls and surviving through the winter, providing a head start in growth that can lead to higher yields than spring-seeded crops. Currently, however, there are no fall mustard varieties available, though U of I brassica breeder Kamal Khadka is working to develop some for Idaho. In the meantime, Spackman believes frost seeding could give mustard yields a slight boost and make the crop more enticing to growers.

For the frost-seeding trial, Spackman will plant mustard on Oct. 15, Nov. 15, April 15 and May 15. He anticipates the October mustard will sprout and die during the winter.

Another component of Spackman’s SCBG project will entail quantifying water-use efficiency and evapotranspiration (ET) — which measures the movement of water into the air from soils and crop foliage — in mustard. Most states rely only on natural rainfall for mustard production. Idaho is an exception and raises most of the nation’s irrigated mustard, but much more research is needed on effective irrigation management for the crop.

Meetpal Kukal, an assistant professor of hydrologic science and water management, will assist in the project, tracking data from monitoring stations placed in a commercial mustard field on weather conditions and ET.

The goal will be to develop the first crop coefficients for spring mustard raised under irrigation. Irrigators use crop coefficients to predict ET and anticipate a specific crop’s water needs. Currently, farmers use spring wheat coefficients as an analog for spring mustard.

A third prong of the project will involve adjusting the rate and timing of nitrogen applications to optimize yield. Spackman hypothesizes that mustard may use nitrogen more efficiently if the nutrient is applied two or three times throughout the season instead of all at once near the beginning of the growing season. This multi-application process would target different growth stages, hopefully reducing competition with soil-borne microbes. If Spackman is right, his fields will require lower rates of nitrogen application but produce comparable yields.

Demand for domestically raised mustard is on the rise. Furthermore, Spackman believes mustard could provide an important nematode-management tool for cereal farmers, for whom applying soil fumigants to control nematodes isn’t economically advantageous. A chemical found in mustard has proven to be an effective, natural nematicide.