By Brent McGhie, UC Master Gardener of Butte County, May 19, 2017.
The most important advantage to drip irrigation is that it is more efficient than traditional irrigation methods. Drip emitters can be placed to deliver water only where it is needed, so water isn't wasted on unplanted areas. By applying water slowly, drip irrigation also allows water to be absorbed quickly into the soil instead of standing on the soil surface. This means that far less water is lost to evaporation than with flood irrigation or sprinklers. Additionally, because water sinks into the soil rather than puddling, there is less loss due to runoff, which makes drip irrigation a good choice for steep terrain. Another way in which drip systems can conserve water is by installing them under a layer of mulch, promoting even greater water savings by further reducing evaporation from the soil. Last but not least, it should be noted that by saving water, drip irrigation also saves the homeowner money.
Drip irrigation has several other advantages. In addition to water, plant roots also need air and when soil pores are completely flooded, roots can actually “suffocate.” The slow application of water by drip systems virtually guarantees a good soil/water environment with a balance of water and oxygen in the soil. Next, weeds don't grow if they don't have water, so they become far less of a problem when water is efficiently targeted to desirable plants by using drip irrigation. As a bonus, this means that herbicide use can be cut back or eliminated, which is better for both the environment and the pocketbook. A final advantage of drip irrigation is its flexibility. It can be installed in a variety of landscapes and, at a relatively low cost, it can be altered and changed as plants grow.
There are disadvantages to drip irrigation systems that should be considered as well. Sediment or bugs that find their way into the tubing can clog drip emitters. In-line filters can be installed to eliminate most of this clogging, but mineral deposits can also clog emitters. There is really no easy way for homeowners to eliminate this, but clogging due to mineral deposits can be delayed by using emitters with a greater flow rate. For example use a 2-gallon per hour (2gph) emitter rather than a 0.5gph emitter, but run it for a shorter time. The faster flow discourages mineral buildup which can cause clogging.
In addition to problems with clogging, drip irrigation systems, with their softer tubing and plastic emitters, are more easily damaged by animals than irrigation systems made of sturdier PVC or metal components. Some dogs seem to delight in chewing on drip tubing, and drip systems also make tempting targets for thirsty rabbits or squirrels. On the plus side, burying drip tubes in shallow trenches or under mulch seems to be effective in mitigating this sort of damage.
If you are considering installing a drip system, putting it on an automatic timer is recommended. An automatic timer provides a consistent watering schedule. With a timer, you provide the exact amount of water you want and there is no forgetting to turn the system on or off.
Something else to consider when planning a drip system is planting zones. Simply put, this means that the same valve should service plants with similar watering needs. You wouldn't want a drip line that waters a vegetable garden to also serve a cactus garden, because their water needs are so different. A simple, inexpensive pressure regulator is also necessary because drip systems require far less water pressure than normal house pressure. Most emitters cannot withstand pressures greater than 40psi and micro-sprinklers cannot function below 10psi (psi stands for “pounds per square inch,” the measurement standard for water pressure).
Many retailers offer how-to pamphlets that provide further information on drip irrigation components and installation.
Schwankl, Larry, and Terry Prichard. Drip Irrigation in the Home Landscape. Oakland, CA: U of California, Division of Agriculture and Natural Resources, Communications Services—Publications, 1999.
By Brent McGhie, Butte County Master Gardener, February 7, 2014
Since this is shaping up to be one of the driest years in California history, it's appropriate to look at ways to conserve water in the home garden. A good starting point is the garden soil itself. Sandy soils tend to drain too rapidly, while heavier clay soils may drain poorly and not provide sufficient oxygen for plant roots. Adding organic compost to the soil will help rectify both of these situations. Organic material increases the water-holding ability of sandy soils and loosens clay soils, so that they are better aerated.
A lawn is normally the single greatest water-user in the home landscape, so unless it serves a specific purpose, such as entertainment, or a play area for pets or children, you might consider replacing it. Lawn substitutes can include planters, ground covers, mulches or hardscape features such as decks or patios. If you choose to have a lawn, the type of turf will affect water use. Warm season grasses such as Bermuda grass, St. Augustine grass, or zoysia grass typically require about 20 percent less water than cool season grasses like tall fescues or bluegrass. Water only when necessary. If you step on the lawn and it springs back when you move your foot, it doesn't need water. Aerating the lawn will maximize water penetration and the duration of watering should be timed so that excess water does not run off of the lawn due to saturated soil. Adjust sprinklers so that water does not end up on concrete or gutters where it is wasted. For lawns and all landscape plants, watering in the early morning hours when wind and temperatures tend to be low means less water will be lost to evaporation.
If you are deciding what to plant, California natives from our climate zone are a good choice. They will need regular watering at first, but can often survive with little more water than they receive from average rainfall after they are established. Try to limit the use of plants that require frequent irrigation and, for efficiency, group them in areas where they can be watered together.
All plants should be watered only when necessary. Check on soil moisture and adjust your watering schedule frequently to reflect seasonal variations in temperature, wind and rainfall. Any plants with similar watering requirements should be grouped and watered with separate valves. Although sprinklers are the best way to water lawns, the most efficient way to water other plants is with drip or soaker hoses. This minimizes water loss through evaporation or runoff. Infrequent, deep watering results in deeper root growth, which in turn allows plants to develop greater tolerance for hot, dry weather. It is important to maintain your irrigation system, checking for leaks, broken sprinkler heads, clogged drip emitters and other problems that could result in wasted water or stressed plants.
A drought year is not the time to engage in excessive pruning. Such pruning can lead to heavy plant growth and a resulting increased demand for water. Light pruning during the winter can shape a plant without stimulating excess growth. And early summer pruning reduces vigor, leaf area and water demand without stimulating excessive growth.
Over-fertilizing can also result in excess plant growth and extra water consumption.
There are several advantages to mowing lawns slightly higher during hot weather. Their growth rate is slowed (reducing water demand) and deeper root growth is encouraged. Taller grass also shades the soil, which lowers evaporation and reduces weed seed germination.
Finally, think twice before running water. Indoors, for example, flush the toilet only when necessary. Turn off the tap while brushing your teeth. Capture water in a bucket or a large pot while the shower or the dishwater is warming up and use it to water garden plants. Using a broom instead of the hose to clean a driveway can save hundreds of gallons of water. Leaving the hose running while washing a car can waste 150 gallons of water; instead, re-fill a bucket with water as needed, and turn off the hose. It's often just a matter of common sense.
Geisel, Pamela M. "Pub. 8036 Water Conservation Tips for the Home Lawn and Garden." Anrcatalog.ucdavis.edu. UCANR, n.d. Web. http://anrcatalog.ucdavis.edu/pdf/8036.pdf
"Water Conservation in Your Garden & Landscape Checklist." Colusa County Farm Bureau. UCCE, n.d. Web. http://cecolusa.ucanr.edu/files/65442.pdf
Kim, Dohee. "Questions and Answers about Water Conservation." UC Cooperative Extension Connection. UCANR, n.d. Web. http://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=5356
Water Conservation Suggestions for Your Home Vegetable Garden." UCCE Master Gardeners of Trinity County, n.d. Web. http://cetrinity.ucanr.edu/files/180197.pdf