- Author: Reyna Yagi
Reyna Yagi (firstname.lastname@example.org), Northern California Urban Agriculture Program Coordinator, University of California Cooperative Extension - Alameda and Contra Costa Counties
How can we as urban farmers do our part to conserve water? Turns out there are a lot of ways that not only will help to save our beautiful state's water, but also help you build a healthier farm or garden with less work on your hands!
Rainwater Harvesting allows you to capture rainwater from roofs, collect it in a cistern for diversion to your landscape for supplemental irrigation. You should also observe your site's water runoff patterns and see how you can manage and maximize your runoff to deal with large rain events, stormwater runoff and infiltration around your site. Consider a rain garden!
- Dry Farming depends on the water stored in the soil from winter rains that plants can use in the spring as the weather warms. Plants rely on good soil moisture and deep roots to seek out this extra water without needing much supplemental irrigation. Grapes, potatoes, tomatoes, winter squash, fruit trees and grains can be dry-farmed.
- Deep watering wets entire root zones which promotes deeper root growth.
- Always water early in the morning to prevent daytime water loss through evaporation.
- Keep an eye on the weather! A refreshing rain or cool, cloudy day will extend the time between watering.
- Maintenance, maintenance, maintenance. Visually inspect your drip system regularly for breaks, leaks and missing pieces. If you don't, your plants will certainly let you know with plant diseases.
California's agricultural industry is the largest in the nation and abroad, carrying with that a great responsibility to protect and conserve our resources. Urban farmers are highly cognizant of this. They are some of the most innovative and conservation-minded folks out there who understand the fragility of our water supply and their role in being model stewards of our lands and waters.
- Author: Rob Bennaton
- Author: Adapted from an article by the Alameda County Master Gardeners Help Desk
To the many benefits of composting, add another: water conservation. When compost is added to bare soils as a thin layer, it is an effective barrier against evaporation of soil moisture, a practice called top- or side-dressing. Compost also reduces plants' needs for water by increasing how much water can be held by the soil - only a 5% increase in organic material quadruples the soil's water holding capacity.1
[A] 2000 study … found that increasing the water holding capacity of the soil by adding compost helped all crops during summer droughts by reducing periods of water stress. The amount of water in … 8 inches … of the compost amended soil increased to 1.9 inches compared with 1.3 inches in un-amended soil. Since vegetables require 1 inch of water a week, at field capacity, the compost amended soil held a 2-week supply of water.2
Compost is the result of a process whereby a large volume of organic matter is rapidly decomposed into a smaller volume that is then used to amend the soil. Soil particles occur in aggregates or clumps, unless they have a high amount of sand particles that do not hold together well. Soil structure refers to the arrangement of sand, silt and clay particles into larger aggregates.3 One can assess the soil structure for their home or community garden by doing the soil-ribbon test and the soils-sedimentation test. This video from Kansas State University tells you how to assess your soil texture by feel. The bottom line is that amending the soil with compost improves its structure, which significantly affects how well it holds water.
Compost is decomposed organic matter that has stabilized, yet, still continues decomposing, though, at a slower rate. The organisms that break down organic matter release glue-like substances that bind soil particles into crumbly aggregates. These irregularly shaped aggregates have air-spaces between them and can be penetrated and occupied by water, nutrients, and plants' roots. Soils rich in organic material have a sponge-like quality that holds water and, thus, plants growing in them have lower water needs.4 In sandy soils with poor water retention, compost improves the soil's water holding capacity by improving soil structure ie., aggregate stability.
Unlike sandy soils, clay soils are characterized by small spaces between the small clay particles. Clay soils have good water retention capacity, however, the spaces in between the particles can fill with water quickly, excluding oxygen and nutrients, and, essentially, drowning the plants. Water saturation in clay soils may also cause soil runoff because those soils cannot hold more water, but, adding compost aerates clay soils and increases its capacity to hold water, oxygen, and nutrients needed for healthy plant growth.
Ultimately, regularly amending with compost lightens clay soils, thus, reducing run-off, and increases the water holding capacity of sandy soils, hence, reducing the need for water. Adding compost as a thin mulch layer over bare soils reduces water evaporation, while also reducing the need for water by garden and farm raised plants. Top-dressing with compost in combination with a thin top-layer of straw mulch in food-growing areas, or a thin woodchip mulch in ornamental garden areas, can reduce plants' water needs around their roots even more, where water is needed the most.
1 Compost Fundamentals, Compost Benefits and Uses. Washington State University, Whatcom County Extension. Accessed on 28 January 2015.
2 M. Charles Gould. Compost increases the water holding capacity of droughty soils. Michigan State University Extension. Accessed on 28 January 2015.
3 Dennis R. Pittenger, ed., California Master Gardener Handbook (University of California Agriculture and Natural Resources, 2002), 36.
4 For the Gardener: Building Fertile Soil. Center for Agroecology and Sustainable Food Systems, University of California, Santa Cruz (Santa Cruz, CA: University of California, no date provided).