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Microirrigation Uniformity
Uniform water applications are important to ensure that all plants in an irrigated zone receive the same amount of water in a given time. For microirrigation, this means that each emitter delivers a specified amount of water to each container. There is an easy test to evaluate water application uniformity. Measurements of the time required to fill the same container must be performed at a minimum of 18 locations throughout the irrigation zone. The statistical uniformity nomograph (Bralts and Kesner, 1983) is based on the statistical coefficient of variation and can be used to determine the overall application uniformity. If the uniformity is low, more than 18 measurements of time (seconds) may be necessary to increase the confidence level of the uniformity measurement. The uniformity test should be performed every six months.
To perform the test you need a small container (an empty bottle will suffice) and a watch with a second hand so you can record the time to fill the bottle at each location. The following steps are required:
- Determine how many measurements represent one sixth of the total locations in the zone. For example, if a total of 18 measurements are performed, this number is 3.
- Add the lowest three measurements of time (seconds) and mark the sum on the x-axis of the nomograph.
- Add the highest three measurements of time (seconds)
and mark the sum on the y-axis of the
nomograph. - If the sums do not fit on the scale or if the value is too small to read, the sums can be multiplied or divided by a common factor. Read the water application uniformity at the intersection of the two lines passing through these points.
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"Uniformity
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