By Patricia Acklin, Chair, ACC Water Conservation Action Team
There is growing interest in the American West in a technique called dry farming, which allows growers to forgo irrigation. This does not mean growing plants without water. Instead, dry-farmed plants use water already stored in the ground (which is also different from rain-fed agriculture). Dry farming is used in many regions of the world, and is often associated with Mediterranean climates. It was also common among Indigenous peoples in North America before colonial settlement.
Generally, dry farming requires a rainy season of more than 50 centimeters (19.6 inches) of annual precipitation, followed by a dry growing season. The soil must be fine enough to allow water to permeate but also retained over time. Plants are set out as early as possible to use existing soil moisture to get started. Wider spacing, planting in furrows to reduce evapotranspiration, and adding an insulating layer of mulch on top of the soil also encourage plant roots to extend deeper into the soil in search of existing moisture as the growing season progresses.
Plants grown in the Northwest using dry farming include:
Tomatoes
Melons
Potatoes
Squash
Beans
Research on dry farming is currently underway in and around Portland and the Willamette Valley by Oregon State University (OSU), nonprofit organizations, and private citizens. OSU is also conducting research here in the Rogue Valley at the Southern Oregon Research and Extension Center. They’ve had success in growing tomatoes, summer and winter squash, some melons, and corn for grinding into flour. Five varieties of melon are being planted this spring!
Dry farming practices must be adapted to accommodate differences between the climates of the Rogue and Willamette Valleys. In the Willamette, rainfall extends later into the spring and begins earlier in the fall, and it is also a little cooler. The warmer, drier climate here causes increased reliance on methods such as addition of organic matter to the soil for increased water retention and nutrients, increased mulching, and planting of cover crops.
For farmers, an agrometeorological station can be used to measure meteorological data such as temperature, rain, air humidity and other variables. Dry farming yields are often smaller but the flavor is more intense.
If you are interested in experimenting with dry farming, there is support available through dry farming collaboratives, according to Diane Choplin of the Small Farms Education Program at the OSU Extension Service in Jackson County.
If you are interested in experimenting with dry farming, there is support available through dry farming collaboratives, according to Diane Choplin of the Small Farms Education Program at the OSU Extension Service in Jackson County.
