Water, Water Everywhere, Yet Not a Drop to Drink About
The hills in Northern California turned golden brown earlier than ever before. Fruit is ripening on the local plum trees, a month earlier than usual. These events, and the news of the drought, have me thinking about water and where rain comes from.
As children, we understand the water cycle: Water evaporates above the Pacific, rises into the air and clouds, travels across California to the Sierra Nevada, falling as rain and snow.
We are so close to the ocean, water vapor surrounds us. Humidity is in every breath — in from the air and ocean, out from our lungs and body.
But what causes precipitation?
The 3 factors in rainfall are water vapor, trees and healthy soil.
Sixty percent (Yes! 60%!) of all rainfall is the result of the small water cycle.
In most locations, the small water cycle is driven by plant respiration. The water vapor condenses on bacteria which originated in healthy soil.
It is the respiration of trees and plants that are the primary source of water vapor, unless you are close to the ocean. They feed the bacteria and other microbes in the soil. The leaves of trees provide coolness, shelter and surface area that encourages dew. And the movement of leaves in the wind plays a part in bacteria taking flight.
Take the Coastal Live Oak, as an example. Each tree can release up to 500 gallons of water, daily into the air, through pores on the underside of its leaves. While they vary in size according to local conditions, old trees can have tap roots that can go down 36 feet. Every coastal life oak has an extensive network of horizontal roots, which catch the subsurface rainwater runoff. The roots provide food to the soil microbiome, increasing biodiversity AND increasing the potential for rain.
Tree planting, therefore, assists in reducing the impact of the drought through rain, through water retention in the soil, through the increase in dew (hyper local water), and contributes to the restoration of the groundwater.
Trees and other plants have been under unrelenting attack as many public leaders call for elimination of landscape watering. Most of these attacks appear misguided when one looks at the science and the facts.
“Research has clearly shown that many, if not most, common trees, shrubs and groundcovers not traditionally considered drought tolerant or low-water use are actually very drought tolerant once established if cared for and irrigated properly” writes Donald Hodel of University of California’s Cooperative Extension (UCCE). “Selecting the right tree for the situation, and then planting and maintaining it properly are critical to conserving water.” The full article, The California Drought and Landscape Water Use can be found here. https://ucanr.edu/sites/HodelPalmsTrees/files/215524.pdf
The cost/benefit analysis clearly shows that landscape plants, especially trees, are worth the investment in resources, especially water, even in severe drought. Trees are a key component of how water vapor turns into the rain we need to end the drought.
SymSoil is a soil health and soil biology company which has a patent on a process to mass produce Robust Compost (with full spectrum soil biology) and Fortified Compost (previously known as V50) which contains significant amounts of preconditioned biochar.