AgBioResearch

Michigan vegetable producers are facing an increased incidence of extreme weather events — such as drought, heat and heavy rainfall — that place extreme stress on crops. New cropping systems are needed to help reduce the risks associated with these events.

Daniel Brainard, associate professor in the Michigan State University (MSU) Department of Horticulture, is undertaking a range of research projects to build resiliency in vegetable crops. He is looking at reducing tillage and maintaining crop residues on the soil surface, two principles basic to conservation agriculture.

His current projects include several long-term trials exploring the best way to implement strip tillage systems to build soil health, increase moisture retention and protect tender crops, and develop new irrigation systems to reduce heat and drought stress for historically nonirrigated Michigan vegetables.

Strip tillage involves tilling fields in straight lines separated by a strip of untilled soil where a cover crop may be planted. For some crops, such as carrots, the cover crop strip can protect the cash crop when plants are small and vulnerable. When the cover crop dies and is left on the soil surface, it acts as mulch and helps to preserve soil moisture and prevent erosion.

With support from other MSU specialists and MSU Extension educators, Brainard’s long-term strip tillage trials have shown beneficial increases in soil organic matter and improvements in soil moisture under drought conditions, along with reduced labor and fuel costs for tillage.

“Part of what we are looking at is what crops strip till systems work for,” Brainard said. “What are the potential benefits? What are the constraints, and what are complementary practices that people could integrate into that system to make it work — including adjustments in weed and nutrient management practices. Growers need to be aware that, if you’re going to try this, you’re also going to need to make other adjustments in the system to make it work.”

Strip tillage sometimes requires a specialized approach to weed management because weeds that were previously controlled with tillage can spread and interfere with the crop. Weeds emerging in the tilled in-row zone are particularly challenging to manage without damaging the crop. This is not a major issue for crops with suitable herbicides, but it is for those crops without herbicides or for organic growers.

To help address weed management challenges in both strip tilled and conventionally tilled vegetable crops, Brainard received a Partnership Grant from the North Central Region SARE program (Sustainable, Agriculture, Research and Education) to travel to Europe with three Michigan growers to study in-row cultivation tools (weeding machinery) and bring them back to test in Michigan. These were demonstrated to more than 100 growers at the Midwest Mechanical Weed Control Field Day and will be featured in an upcoming series of videos.

“We have learned that many of the European growers are successfully using in-row tools such as finger and torsion weeders, which aren’t being used very much here,” Brainard said. “And we’ve learned quite a bit about where these tools work best — in specific crops and soil conditions — and where they don’t work so well. We’ve spent time learning how to calibrate these tools to work best so that Michigan growers don’t have to.”

Through a long-term trial, Brainard has also developed a system to irrigate asparagus that increases yields and reduces heat stress through evaporative cooling. The evaporative cooling helps prevent the asparagus from growing too quickly during hotter spring months, which causes the asparagus spears to open, making them unappealing to consumers.

“Irrigation can be very valuable for certain varieties of asparagus, especially on light, sandy soils,” Brainard explained. “There is a newer variety called Guelph Millennium that is not as drought-resistant or -tolerant as some of the older varieties, so to make that work in Michigan, it has helped for some growers to have irrigation in place. Our long-term trial has shown about a 10 percent boost in yield with irrigation on average over the past seven years.”

Brainard’s work is made possible by funding from USDA initiatives such as the Organic Agriculture Research and Extension Initiative, MSU Project GREEEN (Generating Research and Extension to meet Economic and Environmental Needs), and support from Michigan vegetable commodity groups such as the Michigan Vegetable Council and the Michigan Asparagus Research Board.

Though his research in both irrigation and strip tillage seeks to reduce risk for farmers, Brainard said there are also risks involved in trying anything new, and that research cannot eliminate all of them. Ultimately, for growers, the most important question is should they make the investment?

“When growers invest in an irrigation system, they are making a decision about buying infrastructure not just for that year but for the whole life of the asparagus,” he said. “They know that some years it is not going to need irrigation, but they also know that some years it might. The system might not get used for three years, but if you have that one really hot, dry year and you use it then and you get 20 percent increase in yield? It pays for itself.

“That’s why I like to do long-term trials, where you can start to get a feeling for this risk avoidance. You’re going to have some years when something bad will happen that you can’t anticipate. But if you have your systems set up well, they can survive that.”