At last month’s chapter meeting, that Amy Garrett from OSU said we don’t need to water our vegetables! Okay, she didn’t EXACTLY say that. Maybe it was more like, in some areas, with some soils, with some techniques, with some vegetables, you don’t need to water. That’s still pretty impressive. How could that work?
We all remember that the typical water requirement for vegies is an inch of water per week. On hot weeks a bit more, on cool weeks a bit less. We also know that our vegies typically take about 12 weeks to be ready for harvest. Getting out my calculator I figure that means 12” of water. As I recall, it doesn’t rain in the summer around here!
But suppose you lived in an area where it rained a lot in the winter, but not in the summer. Anyone live in a place like that? Let’s also suppose that several thousand years ago, some massive floods deposited a lot of soil in your neighborhood. Let’s say that soil is -oh- 4 feet deep, and is a silty clay loam. Do you remember that picture they showed during our training with the soil and the spaces for air and water? As I recall, it suggested an average of 50% soil, 25% air, and 25% water. Now if we’ve got four feet of soil, and 25% of it is water, let’s see… carry the two… cube root… divide by… to the second power… Why, that’s 12 inches of water! That’s an inch of water for every week my vegies are thirsty, right under my feet!
It must not be that easy. Sure, if our soil is not compacted, and not overly tilled, capillary action will slowly bring most of that water near the surface, but now that I remember, you can’t get all the water out of the soil. Also, when the water gets to the surface, the sun is going to do its best to evaporate that water before our vegies can get it. That must be why she said “with some techniques”.
We can cut down on the evaporation if we’ve got mulch. Even a dust mulch is helpful. Just a light hoe or rake after a rain to make an insulating layer of dust. (You have to ignore the folks who shout, “Its dry as a bone!”) If we really can’t get all that water, we should maybe go with larger spacing between plants so they don’t fight one another for the water. We could also plant varieties that do best in dry farming situations. How do you find those? They’re working on that. There’s a lot of selection and seed saving going on among the many farmers who are giving this dry farming a go. The Dry Farming Collaborative is a collection of folks with at least some of their land under dry farming. They’re keeping records, and folks at Oregon State University are running trials. This all might seem uninteresting to many folks, but there are already a number of farmers who have little or nothing in the way of water rights, and there is this nagging rumor in the scientific community that our climate just might be changing!
Does it work? Amy showed us a bunch of pictures and graphs that sure gave that impression based on the trials with the Dry Farming Collaborative. More info can be found here: http://smallfarms.oregonstate.edu/dry-farm/dry-farming-project.
Check out these other references about dry farming approaches in our region:
Movie: Search “Vimeo Back to Eden” (be aware - lots of scripture quotes)
Book: Steve Solomon - Growing Vegetables West of the Cascades
Book: Steve Solomon - Water-wise Vegetables
Book: Steve Solomon - Gardening without irrigation, or without much anyway
Book: Steve Solomon - Gardening When it Counts
Book: Carol Deppe - The Resilient Gardener
Book: David Granatstein - Dryland Farming in the Pacific Northwest
Website: California Ag Water Stewardship Initiative - http://agwaterstewards.org/
Book: John Widtsoe - Dryland Farming: A System of Agriculture for Countries under low rainfall.
PDF: Dry Farming Collaboritive, Amy Garrett - https://wrdc.usu.edu/files-ou/publications/dry-farming-garrett-rcspr2017.pdf