ET or evaporation transpiration rate is the amount of water loss experienced by plants. The ET Rate is the amount of water needed to be replaced. Each plant or crop is assigned a percent (K Factor) of that rate based on plant needs.
The daily evaporation is measure in Inches, sprinkler run times are in minutes determine by their precipitation rate(PR). The chart shows the run times for various sprinkler outputs when the ET Rate is 1 inch for the week. Based on the K Factor you would have to irrigate a lawn ( 60% of ET ) 24 minutes for fixed heads, 72 minutes weekly for rotor sprinklers. Assuming the precipitation rate for fixed heads is (1.50PR) and rotors (.50PR)
Fixed heads have a large range of precipitation rates up to about 1.5 or 1.7PR. The distance sprinklers throw will impact volume. As a general rule do not exceed 6 minutes on run time to avoid soil saturation and run off, on fixed head sprinklers
A rotor or impact puts out approximately.05 inches precipitation (.50PR) in a hour, it usually has a fine stream and rotates.
The information on this page is a guideline for drought prone landscapes, similar to the San Francisco North Bay Area, which traditionally has long stretches of drought, compounded by several years of heavy rains and flooding, then repeats the pattern every decade or so.
Managing the upper canopy of the landscapes dictates the growing pattern and the best investment property owners can make in their landscape is having a licensed arborist come out every two years for trees over 15 to 18 feet.
Keeping trees healthy and shaped helps shrubs and ground cover thrive, controlling and minimizing the canopy will keep the root growth in check and help minimize stress in drought.
Plant selection is sometimes dictated by choice, other times chance of survival. The ideal tree for beauty, function and enjoyment is sometimes planted with the intent of it being trained to fit the location.
The legginess of tree canopies can be from surviving drought, or competing for sun as landscapes mature. End of summer or Fall Equinox pruning is a way of communicating with tree roots to let them know what size specimen they are supporting. Scaling back canopies is a way of removing air condition and shade from the roots, signaling to the plant there is less to support.
Plant life focuses on root growth during the winter months, providing top dressing (amendment, and top soil if needed), aeration from blending and mulch for water retention and helps improve the habitat
Gas powered garden tools emit 5% of the nation's air pollution.
The average homeowner spends 40 hours/year, the equivalent to one-week vacation, mowing the lawn.
30% to 60% of urban freshwater is used for watering lawns (depending on locale).
A 1,000 square foot lawn requires 10,000 gallons of water per summer to maintain a "Green" look. (US. News and World Report, 10/28/96)
80,090,000 pounds of synthetic pesticides are used on US. Lawns each year.
When pesticides are regularly applied, 60-90% of earthworms are killed. Earthworms are invaluable for soil health. (PA Department of Agriculture)
Over 100 million tons of fertilizers are applied to residential lawns and gardens annually. (Audubon)
Redesigning the American Lawn by Herber Bormann. Diana Salmon, Garden Geballe, Yale University Press, 1993.