How to Calculate the Precipitation Rate for a Bubbler

Steps

• 1

  Place a 5-gallon bucket under the faucet that will deliver water to the bubbler. Turn the water on to the volume you'll use for irrigation. As you turn it on, start a stopwatch. When the bucket is full, stop the stopwatch. As an example, say it takes six minutes, or 360 seconds.

• 2

  Divide the time in seconds that it took to fill the bucket into the number of gallons in the pail (five). That would be 5 divided by 360, which equals 0.014. Multiply 0.014 by 60, which equals 0.83. The product is the gallons per minute (GPM) delivered by the faucet at the volume you have selected.

• 3

  Multiply the GPM by 96.25, which converts GPM to inches per hour. (This is arrived at by dividing 60 minutes per hour by the universal rate of 7.48 gallons per cubic foot times 12 inches per foot.) In our example, 0.83 times 96.25 equals 79.89.

• 4

  Divide the product by the number of square feet of soil above the mature root system of the plant irrigated by the bubbler, which is known as its total root area. The quotient, expressed as inches per hour, is the precipitation rate for the bubbler. In our example, if the total root area of the tree you want to water is 125 square feet, divide 79.89 by 125, which equals .64. The precipitation rate of your bubbler is 0.64 inches per hour.