Blending Tradition and Technology to Preserve Arid-Adapted Seedlines
Irrigated dry farming sounds like a contradiction. And that’s because it is. But in our NS/S seed grow-outs, that contradiction may be the key to sustaining the health of the seeds in the seed bank while also preserving the arid adaptations that Indigenous seed keepers have cultivated over generations.
For thousands of years, dry farming, growing without any supplemental irrigation, has been standard practice in the Sonoran Desert. The O’odham word, ak-chin, meaning “mouth of the wash,” refers to the farming practice of planting in washes or arroyos to utilize the rainwater and nutrient-rich sediment that comes down from mountain foothills. Growing seeds in the rigorous conditions of ak-chin dry farming naturally selects for resilience and efficiency. Over generations, these practices have shaped hundreds of varieties of arid-adapted food crops like O’odham 60-day corn, tepary beans, devil’s claw, and more. While dry farming facilitates great resilience, it is not without risk. As we’ve experienced in recent years, sometimes monsoon rains come very late, or not at all. In those seasons, a dry-farmed crop may be lost entirely.
As we grow seeds to regenerate the seed bank and increase availability to growers, we are always thinking about how to balance resilience and reliability. Tohono O’odham dry farmers have rightfully reminded us that an over-irrigated crop loses resilience and the seeds produced may no longer be of value to the community that shaped that seedline. At the same time, if we exclusively practice dry farming, we risk losing entire seedlines in a poor monsoon season. In the context of the seedbank, this would also be a failure to appropriately care for these seed lines.
Enter the contradiction of irrigated dry farming, also known as deficit irrigation. In our newest addition to the Conservation Center, we learned from the field design at the Tohono O’odham Community College farm. With a homemade water level, tractor, and a lot of hand shoveling, we dug a 20-bed basin field that captures monsoon rainwater from three directions. Rainwater harvesting basins trap sediment, and then the overflow fills the basin field. We saw this work beautifully during a 1.5” rain in late June. While this field is designed to mimic some ak-chin practices and maximize rainwater capture, it is also connected to our irrigation system so we can supply supplemental water as needed during critical periods of crop development.
This spring, we grew Gila Pima A’al Hu:ñ, a 60-day corn that thrives in low water conditions. Instead of setting up a regular irrigation pattern for this growout, we practiced deficit irrigation–using rain as the primary water source and waiting as long as possible between supplemental irrigations, often 2-3 weeks or more. Though the corn was not truly dry farmed, this was the least amount of water we’ve applied to a corn grow-out at the Conservation Center, and the plants produced healthy, viable seed.
While we have a lot more learning and experimenting ahead, by combining modern drip irrigation technology with the design practices of ak-chin dry farming, we hope to appropriately balance resilience and reliability to ensure these seeds continue to meet the needs of the seed keepers who have invested so much care into their cultivation and will continue to do so for generations to come.
Pictured above: New dry farmed plot after a heavy rain in July. Photo credit: Kristen Densmore, Garden Assoc. Americorps
This piece is republished from The Seedhead News No. 130. You can read this full Seedhead News edition here>>