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Greener Fields: Sustainable Systems for Potatoes
 
Plant physiology professor Robert Dwelle defines “sustainability” for his freshman class in plant science as “meeting the needs of the present without jeopardizing the ability to meet the needs of future generations.”
     How are University of Idaho scientists and educators working to develop and implement sustainable cropping systems for potatoes—the crop in which Idaho has led the nation in production since 1957?
     Bingham County, blessed with good soil and plentiful water from the Snake River and aquifer, is the largest potato-producing county in the U.S. The traditional potatoes-wheat rotation results in a build-up of diseases, nematodes (tiny, unsegmented worms that attack roots), and weeds, so most farmers fumigate the soil, which is costly and can result in water contamination.
     Jack Brown, a plant breeder at UI, says, “There is a tremendous impetus in many countries to find 		 
UI crop nematologist Saad Hafez examines forage radishes during a green manure field day and farm tour near Blackfoot.
alternatives to synthetic fumigants because these will be banned soon. Brassicas—mustard and rapeseed, for example—are ideal; when they break down they release exactly the same toxic compounds as the synthetic fumigants.”
     In Bingham County, extension educator Brian Finnigan makes the results of research available to farmers. “I’m trying to help farmers see that when you incorporate sustainable practices into your cropping systems, you can maintain your profitability and improve your soil and water quality.”
     Including green manure crops in rotations is one time-honored sustainable practice. The benefits of plowing under crops such as legumes, brassicas, vetch, and buckwheat are multiple.
     “For years, a farmer near here has been taking one third out of production each year and growing Austrian winter peas as a green manure crop,” said Finnigan. “He has achieved a dramatic reduction in pesticide and fertilizer use and a gain in yield and quality in wheat and potatoes.”
     Last fall the University of Idaho, Northwest Coalition for Alternatives to Pesticides, Natural Resources Conservation Service, and Idaho Rural Council sponsored a farm tour to provide information about green manure crops.
     At Steve Goodwin’s farm, potatoes will be planted in May where radishes were turned under and will be evaluated in the fall for diseases, nematodes, quality, and yield. “Results will show that radishes ahead of potatoes produce better potatoes,” claims Finnigan.
     Saad Hafez, nematologist at the UI’s Parma Research & Extension Center, has demonstrated that radishes and mustard ahead of sugarbeets reduce sugarbeet nematodes. And Jim Davis, plant pathologist at the UI’s Aberdeen R&E Center, says his research shows that “we can control a serious and costly disease, verticillium wilt [early dying disease], by using sudan grass or corn as green manure.”
     Garden-variety brassicas are not quite tough enough, so Brown’s group has produced hybrids of mustard and rapeseed. “We’ve increased the concentration of glucosinolates [the compounds that produce toxic substances] fivefold plus changed the type to make it more toxic.”
     “We’re on the right track,” says Finnigan. “A green manure crop must be treated like a crop, but farmers do want to reduce pesticide use for cost savings and improving environmental quality.”
     For more information, call (208) 885-6681.
 
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