Help save our precious natural resource :Water Wondering if you are over watering or under watering your lawn ?
Concerned about the water shortage ?
Here are some proven steps to calculate the correct amount of water your lawn needs .
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The following is an exercise that will walk you through the process of “ how to do a water audit .” Considerations to bear in mind are 1 ) it is based on your having only one station for a given area , 2 ) the area has similar soils throughout , 3 ) shade and sun areas have been separated for valves , and 3 ) irrigation schedules are being set for plant material that has been established . For the sake of this exercise , the example used is turf ; however , other species can be used . Evapotranspiration rates for varying plant material will need to be adjusted as appropriate . Items needed :
• Water auditing cups
• Paper & pencil ( to draw a diagram of the area and marking water auditing results ).
• Ruler or tape measurer ( if water auditing cups do not have measurements on sides ).
• CIMIS data table ( see below )
Step 1 : Place a catch can device ( Grass Farm Water Auditing cup ) by a sprinkler head and half way between the next sprinkler head .
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Note : For hard soils , it ’ s best to push from the inside of Grass Farm ’ s water auditing cups so as not to break the bottom of plastic cup .
Step 2 : Turn irrigation system on for fifteen minutes .
Step 3 : Take measurements from each cup
Step 4 : Make adjustments to sprinklers where needed . Water between catch cans should not be more that ¼ ” different . If results show greater differences sprinkler adjustments should be made . This may require changes in nozzles , head placement or in extreme cases complete overhaul of irrigations systems and their installations .
Step 5 : Take measurements and find your average precipitation rate found in the catch cans and divide that value into the amount needed for the desired irrigation month . Typically , a watering schedule every third day is recommended . So you would divide the precipitation rate ( found in the catch cans after your 15 minute run time ) into
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the amount of water needed for the month . For example if you had a ½ ” average of water after your run time and you wanted to set your irrigation system for the month of July in San Jose : 7.11 / 10 = . 711 per water application . If your system puts out ½ ” of water in a 15 minute period you would need to run approximately 21 minutes to apply 7 tenths of one inch . Ideally you would apply this in two applications to take advantage of low evaporation , winds and to avoid runoff . This also allows the applied water to soak into the ground before the sun comes up .
Note : when auditing your irrigation system mark down how much time it takes before you see runoff on sidewalks or other hard surface areas . This will be your maximum run time . This is best used to avoid “ runoff ” of irrigation waters into gutters and other areas which do not need water .
Step 6 :
Program run time into irrigation timer .
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Jan |
Feb |
Mar |
Apr |
May |
June |
Jul |
Aug |
Sep |
Oct |
Nov |
Dec |
Total |
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San Jose |
1.35 |
1.87 |
3.45` |
5.03 |
5.93 |
6.71 |
7.11 |
6.29 |
4.84 |
3.61 |
1.80 |
1.36 |
49.35 |
Woodside |
1.83 |
2.20 |
3.42 |
4.84 |
5.61 |
6.26 |
6.47 |
6.22 |
4.84 |
3.66 |
2.36 |
1.83 |
49.54 |
San Benito |
1.15 |
1.62 |
3.08 |
4.64 |
5.58 |
6.37 |
6.88 |
6.47 |
4.78 |
3.68 |
1.66 |
1.24 |
47.15 |
Morgan hill |
1.22 |
1.65 |
3.42 |
4.84 |
6.22 |
6.85 |
7.44 |
6.47 |
5.08 |
3.42 |
1.77 |
0.98 |
49.36 |