Kansas State University researchers have received national recognition for a study showing that planting a mustard cover crop helps to improve soil health and ultimately boosts soybean yields.

Our work, funded by the Kansas Soybean Commission, has been recognized by the Supporters of Agricultural Research, a non-partisan coalition that helps to increase federal investment in agriculture. Our research team looked at how we can manage soil health to improve its productive capacity.

Farmers in southeast Kansas know all too well that the soil in the region contains an abnormally inflated amount of charcoal rot. That’s a fungus that chokes the plant’s recycling system so it cannot receive nutrients or water, ultimately killing its roots. Charcoal rot tends to be worse in hot dry conditions, and that’s what happens in Kansas in the summer. We are hot and dry, and the charcoal rot grows and infects our soybean plants.

There are chemical treatments for charcoal rot, but we were interested in finding natural agents to counter the effects of the fungus. It led us to a mustard-seed cover crop, the same plant that’s used to make the condiment that many like to squirt on hot dogs.

The plant has an increased glucosinolite concentration. Glucosinolate is the “tang” we like in mustard, but in soil the glucosinolate produced in the mustard plant acts as a bio-control of the charcoal-rot fungus. The species used in the study is different from a weedy mustard cover crop that is better off sprayed and killed with a herbicide. During two growing seasons our researchers showed that planting mustard seed as a cover crop reduces the incidence of charcoal rot in the soil.

Mustard seed has actually been shown in other systems to improve overall soil health. The approach I’m taking is more of a holistic approach. For example if a person is healthy, they might come into contact with people with a cold, but they won’t become sick themselves because they are overall healthy. In the same way if we can support the soil in a positive way with positive microbes and things that they need, it improves the overall soil health. The soil will be better able to manage diseases that are naturally there all the time.

The researchers also tested various management options, including planting soybeans into standing mustard seed, mowing it or tilling it to incorporate residue into the field. Our key finding is to leave the mustard crop as intact as possible. If we just rolled the mustard cover crop over the top of the soil and planted straight into that, that was the best in terms of reducing charcoal rot.

We are continuing our work, including looking at effects on yields due to Sudden Death Syndrome and soybean nematodes. It’s been suggested that the mustard can control those or have some impact on preserving yield when those are present. But we don’t know for sure.

Again it’s a holistic approach to soil health and seeing more bushels per acre. There’s a lot of promise with mustard seed as being a mechanism or a tool that can be used to improve overall soil health.

Researchers included Chris Little, Xiaomao Lin and Kraig Roozeboom. The Supporters of Agricultural Research featured the Kansas State University study in the report, “Retaking the Field: Science Breakthroughs for Thriving Farms and a Healthier Nation,” highlighting several pioneering research projects in the United States.

Visit supportagresearch.org for more information.

Gretchen Sassenrath is a research agronomist at the Kansas State University Southeast Research-Extension Center. Visit www.southeast.k-state.edu for more information.

Gretchen Sassenrath is a research agronomist at the Kansas State University Southeast Research-Extension Center. Visit www.southeast.k-state.edu for more information.