Jumbo. Colossal. Super colossal. The superlatives used to rate Treasure Valley
onions suggest they could take over the world. And in a way, they have. Many
of the onions sold in U.S. grocery stores during fall and winter come from
this valley at the border of Oregon and Idaho.
After 20 years of research, scientists at OSU’s Malheur Agricultural Experiment Station have helped Treasure Valley onion producers triple their acreage in
onions and reduce water use, pesticides, fertilizer, and runoff. And, in the
process, the onions got bigger.
But the story wasn’t always this sweet.
Back in the mid-1980s, years of tractor-operated cultivation had compacted
onion fields in Treasure Valley. Traditional furrow irrigation was sending
water, fertilizer, and pesticides across the surface of fields, and beyond.
Nitrate and residues of the herbicide DCPA seeped through the soil into groundwater.
“We could see regulations were coming down the pipeline,” said Clint Shock,
superintendent of the OSU research station, appropriately located on Onion
Avenue in Ontario.
Shock experimented with drip irrigation to replace the old furrow system.
He was able to apply moisture and fertilizer slowly right to the root zone,
keeping topsoil in place and protecting water quality. And, with no water splashing
onto onion leaves, drip irrigation reduced the chances of disease.
Shock and colleagues continued their experiments. They developed systems that
released water only when sensors indicated that soil moisture had dropped below
a particular level. At the same time, breeding programs by private seed companies
developed improved onion varieties for Treasure Valley, and growers adopted
herbicides that would break down quickly, replacing stronger, long-lived chemicals.
With water and fertilizer dripped directly to the roots in measured amounts—and
only when needed—onions grew large and well-centered, perfect for making onion
rings. And the results are measurable beyond the onion fields.
“Twenty years of groundwater sampling indicates that residues of the herbicide
DCPA are decreasing in the Valley,” said Shock, “and nitrate residues are also
starting to decrease, despite the three-fold increase in onion production.”