Itâ€™s called the kitchen sink treatment among the scientists involved in a four-year, 10-state research project analyzing how to replenish depleted soils in potato rotations.
Essentially, the researchers throw â€œeverything but the kitchen sinkâ€ into improving soil health in their plots â€” fertilizing with composted dairy manure and planting a crop as â€œgreen manureâ€ between rotation crops. Green manure maintains living roots to limit erosion and to â€œleakâ€ additional nutrients, before being plowed into the earth to further boost organic matter.
The research project â€” heading into its second season in major potato production states including Idaho â€” is evaluating more than a dozen treatments in two- and three-year potato rotations. The goal is to determine which treatments are best at boosting soil health, what makes them work and whether or not theyâ€™re cost effective.
â€œYou hear a lot of people talk about the need to improve our soils, and I believe thatâ€™s true â€” I donâ€™t know any grower who doesnâ€™t want to improve their soils â€” but in the end itâ€™s got to pay for itself,â€ said Jeff Miller, who is maintaining trial plots for the project at Rupert-based Miller Research.
The project is funded with an $8 million Specialty Crop Research Initiative grant, offered through the USDAâ€™s National Institute for Food and Agriculture. It includes 24 research collaborators from Idaho, Washington, Oregon, Montana, Colorado, North Dakota, Minnesota, Wisconsin, Michigan and Maine.
â€œA lot of growers are doing green manure and seeing tangible benefits. Is it microbes of the soil or a change in the physical properties of soil? Those are questions we hope to answer,â€ Miller said.
University of Idaho Extension researcher Mike Thornton heads the research in Idaho. UI Extension plant pathologist Brenda Schroeder, UI agricultural economists Chris McIntosh and Alex Maas and several others are also involved.
Miller said specific soil-health treatments may also come with barriers preventing some growers from adopting them, such as high fertilizer costs or scarcity of water to irrigate extra cover crops â€” which are crops planted solely for soil-health benefits.
University of Minnesota soil scientists Carl Rosen is spearheading the grant. â€œIn a lot of our production systems we talk about chemical inputs, fertilizer and some of the physical properties of soils, but we often neglect whatâ€™s going on in the biology of the soil,â€ Rosen said. â€œWeâ€™re really looking at how to improve the biology so we have better nutrient cycling and better disease suppression.â€
Rosen said soil samples from trial plots involved in the project will be sent to his university, where the microbiome and DNA will be measured using new laboratory techniques.