Fields of Yellow and Green
Cover Crops Help Idaho’s Potato and Sugar Beet Farmers Go Natural
In the 1990s, tests on wells at the Fort Hall Indian Reservation in eastern Idaho found high levels of pesticides
in the water supply of theShoshone-Bannock Tribes. For years, area potato farmers who lease around 85,000 acres on the reservation had been using soil fumigants to control soil borne pests like nematodes, tiny wormlike animals that
burrow into potatoes, causing damage.
In order to continue leasing the land—about one-third of Idaho’s total acreage in potatoes—the farmers were forced to find natural alternatives. They have found one solution in “green manure,” a technique that involves planting mustard in the fall, after the wheat crop has been harvested and before the potato crop is planted in the spring. When tilled back into the soil, the mustard releases a compound that keeps nematode levels down.
There were other benefits as well, such as help controlling
erosion on flat, windy potato fields. “One of the farmers at a workshop funded by AFT said he could move through the soil faster; he described the soil as being more ‘mellow,’” says Jennifer Miller of the Northwest Coalition for Alternatives to Pesticides, who organized field days to educate farmers about how the practice works.
The practice also works on another major Idaho cash
crop: sugar beets. Duane Yamamoto, a sugar beet farmer
in the southwestern part of the state, was able to use
radish as a green manure crop to control his sizeable
nematode problem. “It works,” he says. “It’s so much
better for your ground. It gets your microorganisms
But there are drawbacks limiting the spread of the
practice: in addition to extra labor, fertilizer and fuel,
green manure crops require additional water for irrigation,
which many farmers don’t have. But it’s still a valuable
change for the many potato and sugar beet farmers
around the state who have adopted it.
“We need to promote this,” says agronomist Dennis
Searle of the Amalgamated Sugar Company, who worked
with Yamamoto Farms on their green manure project.
“We need to do everything biological that we can. Chemicals aren’t popular. There will be a time when we have to farm without them.”