Tinker was an advocate of living lightly on the Earth by conserving resources and living a joyful life of volunteer simplicity. This post is for local farmers who may not know her legacy and want to continue this important work.
Along with Judy Alexander, Tinker spearheaded the Dryland Farming Project, exploring the limits of what staples can be grown locally with little inputs, especially without irrigation. “We need to research ways that we can locally and sustainably grow staple crops such as grains, legumes, and seed crops.”
Today we have a vibrant farming community and many people share Tinker’s passion. Organic Seed Alliance develops seeds that grow organically with less inputs. Finn River is growing wheat and many others are working together toward a sustainable farming future.
Garden soil acts as a bank account, holding available water.” Tinker Cavallaro gave a presentation based on the Dryland Farming Project ten years ago at the Quimper Grange. Tinker discussed her presentation with me beforehand and I wrote up the handouts. These are some of the notes:
Understanding our climate and the site’s soil properties is the foundation for making smart choices in garden irrigation. Rainfall quantities vary across the Quimper Peninsula. Close to the mountains, Quilcene gets much more rain. Port Townsend is located in the rainshadow of the Olympics, a unique area with less rainfall than most of Puget Sound. The rainshadow of the North Olympics extends from Sequim to the San Juan Islands.
“As crops grow they make heavy withdrawals from the garden soil bank account.” We will investigate more about soil properties but here are some basic tips:
Practices and techniques
- Develop the habit of checking the soil for moisture
- Use drip irrigation or low-volume sprinklers
- Use water-filled containers with holes placed next to larger plants
- Foliar spray or fertigation with liquid fertilizer known as ‘tea’ made of water and organic matter such as compost, manure, seaweed or nettle
- Raised beds hold moisture better than rows do
- Plant seeds and transplants deeper than normal in the soil
Crops that do well with no extra water
Early Spring Crops
- Peas
- Greens: mustard, arugula & early lettuce
- Kale, cabbage, early broccoli & radish
- Direct-sown early carrots & beets that are heavily thinned
- Grains
- Potatoes
Late Spring-Sown Crops
- Field corn
- Amaranth, quinoa
- Winter squash
- Dry beans including field peas, garbanzos, lentils & fava beans
Crops that require summer irrigation
- Celery & celeriac
- Napa cabbage and summer brassicas
- Summer lettuce & spinach
- Onions if you expect sizable bulbs
Understanding the Soil’s Capacity
Our rainy season, extending from fall through winter, provides enough water to bring our soils to field capacity, or the ability for the soil to hold all the moisture possible. Summer rains, on the other hand, are usually insignificant. In our windy location the little rain that falls often evaporates.
As plants grow they make heavy ‘withdrawals’ from the garden soil bank account. Hot sun and wind cause plants to transpire moisture. The roots of plants pull soil moisture from the soil, up through the plant and out the surface of leaves. Foliage gives clues as to the plants ability to conserve water or use it freely. Drought-tolerant plants from dry climates tend to have small leaves or grey foliage. Magnification reveals tiny hairs that shade the leaf surface. The lush foliage of leafy green vegetables on the other hand can withdraw much water if not properly managed.
How plants utilize water
Plant roots, in a symbiotic relationship with soil microbes form a region known as the rhizosphere, the active site for water and nutrient uptake. Plant enzymes dissolve insoluble starches and oils that are required for plant energy and change them into water-soluble sugars. Roots draw moisture from the soil to their ultimate lateral spread and depth. The size of a plant’s roots indicates drought tolerance.
Healthy soil includes air and water. This water can move upward through the soil by a process known as capillary action. Water is drawn up in a wicking action through the gaps between soil particles. Soil texture determines the soil’s capacity to hold moisture. Sand holds one inch of water per foot of soil. Sandy loam (soil with a bit of silt and clay) can retain 2 inches of water per foot; clay soil retains 3 inches of water per foot. The point is that clayey soil holds three times as much water as sandy soil. If the capillary action is not strong enough then the gravitational pull will sink water deeper into the soil.
Cohesion describes when water is attracted to water and adhesion describes when water is attracted to other materials. When irrigation or rain moistens the ground, soil particles act almost as magnets and water adheres to them. Like a wet sponge, the ground is holding as much water as possible. Water is highly cohesive so gravity will pull water deeper into the soil. This happens when the water cannot adhere to the surface of the soil. If the soil structure has enough pores and humus that acts like glue, more water can be utilized. Root systems have to be able to penetrate the soil, become more extensive, and grow deeper to utilize the soil water.
Plants are much healthier if they can aggressively seek new water in soils unoccupied by roots and grow deeper and wider. Not only will vigorous plants be capable of withstanding drought and wind, they will also create more flavors and sugars.
( For more information on this important topic see Steve Solomon’s Growing Vegetables West of the Cascades, Ch 5)
Sustainable Garden Design 