Published in Winter 2024
By: Sophia Nowers (student), Lucas Nebert, Teagan Moran & Matthew Davis Oregon State University
Around the Willamette Valley of Oregon, small farmers and beginning farmers can struggle with access to irrigation water. In order to help new farmers grow food without irrigation, the OSU Dry Farming Project launched a Dry Farm Accelerator Program with funds from the Western SARE Research to Grassroots grant program. A cohort of 11 farmers participated in the Dry Farm Accelerator Program during the 2023 growing season.
What is dry farming?
Dry farming is the production of crops without irrigation during a dry summer growing season. To meet their water needs, dry-farmed crops use soil moisture that is retained from the winter and early spring rains. Dry farming is different from dryland farming, which is unirrigated farming in semi-arid regions, such as the interior west of the USA. In dryland regions, low rainfall may necessitate farmers keeping their fields fallow for one or more years to store sufficient water to produce a crop. Western Oregon receives an average of 48 inches of precipitation annually, meaning that a dryfarmed crop can be grown every summer. In suitable locations in Oregon, farmers have successfully dryfarmed many warm-season crops, such as tomatoes, melons, corn, sorghum, quinoa, amaranth, legumes, squash, and potatoes. The OSU Dry Farming Project conducts research, education, and outreach activities to help farmers produce dry-farmed crops profitably and sustainably.
Small and beginning farmers are interested in dry farming
Small farmers and beginning farmers are often interested in dry farming due to either a lack of water rights or because they have junior or limited water rights. However, there are many other reasons that farmers are interested in dry farming. Some lack the infrastructure or capital investment required to irrigate farmland. Additionally, many urban farmers can accumulate big water bills if using municipal water. Some farmers with a long history of irrigated farming are interested in dry farming to keep land without water rights in production, as a low-input weed management strategy, and for perceived improvements in flavor and storability of dry-farmed crops.
However, dry farming is riskier than irrigated farming. Not only are yields lower, but the risk of crop failure is higher. For example, on certain sites, drought stress in a tomato crop can result in a high incidence of blossom-end rot, resulting in the loss of a half or more of total tomato yields. One thing beginning dry farmers need to understand in order to successfully dry farm is whether their site is suitable for dry farming.
Location, location, location
Dry farming success can be highly dependent on the ocation of a farm or garden. Site suitability for dry farming encompasses many factors including climate, annual precipitation, growing degree days, exposure to wind, and the soil’s available water holding capacity and subsoil constraints on root development. Soil type is extremely important for dry farming, because the soil is the principal water source for the plants throughout the growing season. Thus, a good first step to determining if a plot of land is suitable for dry farming is to determine your soil series. A quick and easy method to do this is to look up how your site is mapped on the Web Soil Survey; however for more certainty, it is recommended to take a 5-foot-deep soil pedon (see picture). Then a determination of the soil’s available water holding capacity (AWHC) can be made—the amount of plant available water a soil can hold against the force of gravity. At least 9 inches of AWHC in a 5-foot deep soil sample is a suitable amount for dry farming warm season vegetables, and 11 inches or more is ideal. Root-restrictive layers such as a hardpan can also reduce roots’ access to valuable subsoil moisture.
Other relevant site factors are important too. Insufficient nutrients and low soil pH can affect root growth and crop development, which can restrict access to soil moisture. Climate and microclimate should also be considered. Hotter and drier sites will be less amenable to dry farming and cooler humid sites. However, farmers will also want to make sure that their site has sufficient growing degree days to mature the crop. Finally, fast winds can pull water away from the crop and the soil. Sheltering the crop from the wind can help improve dry farming outcomes.
What is the Dry Farming Accelerator Program
Many small farmers, urban farmers, and homesteaders involved in the Dry Farming Collaborative are interested in having more hands-on involvement in OSU Dry Farming Project research. So in 2022, the Dry Farming Project launched the Dry Farming Accelerator Program intended to make it easier for growers to adopt dry farming. This included a soil assessment by a soils expert, a soil nutrient test, an introductory dry farming curriculum (https://smallfarms.oregonstate.edu/article/dryfarming-accelerator-program), access to seeds and starts, and access to peer-to-peer groups of growers trialing dry farmed crops on their farms.
Every member of the cohort grew a trial of North Georgia Candy Roaster winter squash to compare the yield of their farm to others. The goal is to give growers a base of knowledge in dry farming and develop dry farming strategies for different climates and soil types in Oregon. Additionally, farmers could participate in multiple other trials including a toolkit for controlling blossom-end rot in tomatoes, “Oaxacan Green” dent corn trials, grafted tomato trials, and “Lilly” melon trials.
Next steps
Now that the 2022 cohort has completed the Dry Farming Accelerator Program, we look forward to continuing to work with them in future trials. We are also making the Dry Farming Curriculum that we produced for the program available to the broader community. If you are interested in learning more about dry farming the Dry Farming Curriculum would be a good place to start. We hope to be able to do more cohorts in the future, and if you are interested you should contact Lucas Nebert at [email protected] or Matthew Davis at [email protected].