The idea of growing watermelons without a drop of water is hard to imagine. But that’s what is happening in western Oregon, where dry-farmed melons, tomatoes, and squash are surpassing irrigated crops in quality and taste. In uber-dry eastern Oregon, wheat has long been grown without additional water, and now a new technique is building soil moisture where every drop counts.
The tasters were skeptical. They made their way past rows of ripe vegetables back to a table where plates of cut tomatoes lay ready to sample. The tomatoes looked luscious, as tomatoes do in August. But these tomatoes were grown without irrigation. The taste-testers picked up toothpicks, speared the wedges, and bit into the tomatoes. Astonishment lit their faces.
The ‘Big Beef’ and ‘Early Girl’ tomatoes grown with no irrigation tasted sweeter, had a firmer texture and deeper color than the same varieties grown with water. “You know when you cut open a fresh tomato and all the guts run out? With these, the guts stay inside, firm and contained,” reported one surprised taster. “But the real difference is how they taste.”
Amy Garrett was too busy to notice. Surrounded by farmers, gardeners, and academics who had never before tasted dryfarmed tomatoes, she fielded questions until her voice rasped from the effort. “The most common question is, ‘How many times did you water,’” says Garrett, an assistant professor of practice in OSU’s Extension Service. “When I repeat, again, that I didn’t add any water at all, they have a hard time getting their head around it.”
Garrett’s Dry Farming Project fascinated the 100 or so people who came to taste the results and satisfy their curiosity about an ages-old but little-used practice that, inconceivably, produced better-tasting vegetables. Earlier in the summer, Garrett had started a 4,000-square-foot trial plot of tomatoes, melons, squash, and potatoes at the Oak Creek Center for Urban Horticulture, at the edge of OSU’s Corvallis campus. She planted two rows of each vegetable variety: one row was irrigated, one was not.
The dry-farmed plants didn’t go thirsty, though. As Garrett planted into the Woodburn silt loam, she compressed the soil surrounding seeds and transplants to start capillary action, lifting soil moisture to the surface to germinate seeds and encourage roots. As the season wore on, vegetable roots stretched deep, tomatoes rooted down 5 feet to harvest the receding water. She kept a thin portion of topsoil fluffed up with shallow tilling as a dust mulch to keep moisture from escaping during the dry summer days.
The droughts in 2014 and ’15 rattled farmers in Oregon. Wells ran dry and some farmers found themselves without water early in the season. Curious about the possibility of farming without irrigation, Garrett met with Dick Wadsworth, a retired farmer in Veneta, Oregon, who had adapted California techniques of dryland vegetable farming to Willamette Valley soils. Inspired by what she learned from Wadsworth and early adopters in California, Garrett planted a demonstration plot at Oak Creek in 2015. The results were so encouraging, she launched a research-based project in 2016 to determine the quality and economic viability of dry farming for small farmers in the Willamette Valley.
Garrett wants to know if dry farming will ease farmers’ increasing anxiety about climate change and its effect on water availability. When she read the predictions made by Willamette Water 2100 (see story in this issue), her resolve strengthened. She recruited Extension colleagues Heidi Noordijk, an education program assistant at North Willamette Research and Extension Center, and Dana Kristal, Small Farms program coordinator at the Southern Oregon Research and Extension Center, to start their own trials. They followed Garrett’s lead, planting well-known varieties side by side, early in the season when the most soil moisture is available for plants. Noordijk and Kristal hosted dry farming events in their regions, and as expected, evaluations by tasters showed the dry-farmed crops have superior flavor, an important consideration to Oregon’s small farmers who sell directly to the public.
The economic benefits are less clear, Garrett says. Some vegetables, such as tomatoes, produce smaller fruit when dry farmed, but richer flavor. Overall yield is lower, because nonirrigated plants are planted further apart to reduce competition for available moisture. And dry farming isn’t suitable for all soils; deep, organic-rich soils with some clay content have more water-holding capacity and lend themselves to dry farming. Shallow or sandy soils are not ideal.
But considering that irrigation consumes as much as 70 percent of the world’s freshwater withdrawals, dryland farming in western Oregon may be a sustainable alternative. To learn more, Garrett will continue to gather data from OSU trial plots in coming seasons, and from the new Dry Farming Collaborative, which includes many small-scale farmers who have signed on to share results. “We need to be proactive about expanding our drought mitigation toolbox,” she says. “Our work is essential for future generations.”
Wind blows through the wheat fields stretching out to the foot of the Blue Mountains east of Pendleton. With it comes dust, a constant reminder that some of the world’s most productive soils are being swept away.
Stephen Machado nods through blowing topsoil dust. “Once it’s gone, it’s gone,” he says. Since the 1800s when farmers first put plow to soil in Eastern Oregon, up to 60 percent of the soil’s organic matter essential for retaining water has been lost. In a drought-prone region where a majority of fields are not irrigated, that’s a nail-biting situation. For 16 years, Machado, an Oregon State University dryland cropping agronomist, has been researching ways to keep farming sustainable by building up soil organic matter, which he likens to currency. Without it, the underground economy starts to fail.
Machado shoves a soil probe into the bone-dry soil of August as he talks about the problems of farming in a region where 16 inches of rain is a luxury. During cropping years, wheat residue—chaff, stubble, roots—adds organic matter. But as soil microbes whittle it away, residue disappears. With none to replace it the following year, supplies drift into the deficit column.
When soil lies bare during fallow years, wind and rain lift it and wash it away. No-till farming, which has become a more common practice in Eastern Oregon, helps by leaving a protective layer of plant debris on the surface. Farmers disturb the soil only once, when crops are seeded with tools designed to drill seed and fertilizer into fields at the same time. But it’s not enough, according to Machado, to build organic matter in the soil.
Back in his office, Machado picks up a jar of what looks like crushed charcoal, shakes it and says, “I believe this is going to help.” The coal-black material is biochar, a soil amendment made by burning plant waste slowly, at high temperatures with no oxygen, a process called pyrolysis.Biochar is being touted as a carbon-negative technology that has some promise in combatting climate change. The process traps CO₂ that trees and other plants have absorbed from the atmosphere. In nature, this CO₂ would make its way back into the atmosphere as the plant decays or burns with oxygen. With pyrolysis, the CO₂ is captured and prevented from reentering the atmosphere. The carbon is locked in biochar, which it can continue to sequester for decades.
Biochar contains miniscule crooks and crannies where water collects and microbes hole up and gnaw on plant residue, releasing nutrients. Researchers, including Machado, have found that one application of less than 10 tons per acre—one percent by volume—is all that’s needed to adequately increase water- and nutrient-holding capacity and increase crop yields. The additional moisture in the soil may allow farmers to plant every year, which boosts organic matter and crop yield.
Biochar has drawbacks. Because of limited supply, the price is steep, but higher yields could eventually offset expense. Machado tells farmers to think of biochar as a capital investment “like buying a tractor, only one that could last forever.”