Author: Amy Garrett, Small Farms Program, Oregon State University

Publish Date: Summer 2015

Three 10’ x 100’ plots have been established at Oak Creek Center for Urban Horticulture (OCCUH) in Corvallis to demonstrate dry farming practices in several crops including dry beans, tomatoes, potatoes, squash and melon. In Western Oregon these crops are typically irrigated with between approximately 12 to 20 inches or 300,000 to 500,000 gallons of water per acre depending on the location, planting date, seasonal variation, irrigation method, and variety (Oregon Commercial Vegetable Production Guides). The dry farming demonstration plots will receive absolutely no irrigation. Varieties and management practices (soil preparation and planting techniques) were selected based on interviews with several established growers experienced in dry farming. Soil temperature and moisture in each plot will be monitored through out the growing season at 6” and 18” (compliments of USDA Hydrologist, Deb Harms, with the National Water & Climate Center).

So what is dry farming?

Dry farming refers to crop production during a dry season, (e.g. summer in the Willamette Valley), and utilizing the moisture stored in the soil from the rainy season. No irrigation is used. The Willamette Valley receives about 40” of precipitation per year, with less than 1” of rain falling during July and August combined. This seasonal drought coincides with the greatest period of transpiration. Dry farmers work to conserve soil moisture during these long dry periods through a combination of management strategies including drought-resistant crops and varieties, planting technique (timing, depth, spacing, and method), tillage, surface protection, and increasing soil organic matter. Regional rainfall and soil type are important considerations for dry farming. A soil with moderate clay content and high organic matter can effectively store water for crop growth during dry summer months. The soil type for dry farming demonstration at OCCUH is a Dayton silt loam, which has some clay content from 15 to 40 inches deep.

Dry farming is not a yield maximization strategy; rather it works with nature to produce sustainable food with fewer external inputs such as irrigation water and fertilizer. (Runsten and Mamen, 2014). Production costs are lower, but yields often are lower as well, and the economics of dry farming are poorly understood. Dry farming is also not a new way of farming. Before the rise of dams and aquifer pumping, dry farming was a staple of agriculture for millennia in places like the Mediterranean, and much of the American West including the Papago Indians in the Arizona desert (Soloman 2009). However, there is little research-based information on what soil types are most conducive to dry farming vegetables or how dry farming management practices affect the vegetable quality and productivity.

Why dry farm?

As our water supply is becoming increasingly affected by climate change through reduced snowmelt, higher temperatures, and drought (Van Horne et al., 2013), water scarcity is becoming a harsh reality in the western region. It is critical for our food security to understand what we are capable of producing in the absence of irrigation. Dry farming practices could assist in diversifying cropping options for some growers on land without water rights or on irrigated land in drought years when the water supply is limited. OSU Extension Small Farms Program is applying for grant funding to further this work with field research focused on yield, quality, and economics as well as mapping the soils in our region that may be conducive to dry farming vegetables to better understand how dry farming management practices may assist growers in our region.

For more information about the dry farming demonstration and upcoming field days visit: http://smallfarms.oregonstate.edu/dry-farming-demonstration

This project is funded in part by the National Institutes of Food and Agriculture under the Beginning Farmer and Rancher Development Program and supported by the OSU Small Farms Program, OSU Department of Horticulture, and the USDA National Water and Climate Center.

Resources

Oregon Commercial Vegetable Production Guides: https://horticulture.oregonstate.edu/vegetable-production-guides

Runsten, D. and Katy Mamen. “Dry farming”. California Agricultural Water Stewardship Initiative (CAWSI). 10 November 2014. http://agwaterstewards.org/index.php/practices/dry_farming

Solomon, Steve. Gardening Without Irrigation: or without much anyway. Valde Books. 2009.

Van Horne, B., Strobel, M.L., and S. Hardegree. Climate Risks in the Northwest. 2013. USDA Regional Climate Hubs: Managing your risk in a changing climate.