Regional Gardening Reports :: National Gardening Association

In the Garden:
Lower South
August, 2005
Regional Report

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This sprinkler system's misalignment and excessive pressure is wasting water.

Irrigation Audits

This long, hot summer season has kept irrigation systems busy providing water for our lawns and landscapes. Future projections in many areas indicate that water supplies may be inadequate to meet demand, and steps need to be taken to make our lawns and landscapes more water efficient. It is also true that in many cases lawns are watered much more than is needed to keep them healthy.

Warm-season turf species, including St. Augustine, zoysia, Bermuda, and centipede, love hot weather. Provide adequate moisture and they will be fine despite the heat. It is best to give your lawn a good soaking with an inch of water and then wait a week to allow it to dry out a little before watering again. Frequent watering invites disease problems and can promote shallow-rooted turf that is less drought tolerant and more susceptible to attack from insects.

Use a rain gauge or straight-sided container to determine how long to run your sprinklers to apply an inch of water. If your soil is a heavy clay, slopes considerably, or is shallow due to underlying rock layers, you may need to apply water in several applications on a given day, with a brief period of time for the moisture to soak in between applications. Shallow soils may not take the full inch of water.

Automated Systems
Automatic irrigation systems are convenient but are often not operating efficiently. This wastes water and thus causes not only higher water bills but also increased sewer bills in many communities where the sewer rates are based on water rates.

Irrigation systems are often poorly designed or out of adjustment. If sprinkler patterns do not overlap properly, some areas will not receive adequate water. We tend to water enough to keep the driest areas green, so some parts of the landscape may be getting much more than they need. The problem may be improper sprinkler spacing, lack of pressure, or sprinkler head adjustment.

If the pressure is too high, sprinklers will produce a fine mist rather than larger spray droplets. This results in drift with much of your water ending up on the street, driveway, or neighbor's lawn!

Some cities offer free system audits for their water customers to evaluate efficiency and detect problems. Likewise some irrigation companies can offer this service. You can get a rough estimate yourself by placing rain gauges or straight-sided containers at various locations around the yard and running the system to check for uniformity. One way to do this is to run the system for 15 minutes and then measure how much water is captured by the various containers. Multiply the depth by 4 to get the rate per hour.

Also note the differences in amounts of water collected by the various containers. This will give you an idea of how uniform the distribution is.

This is a good time of year to make any necessary corrections to your system so it's ready to go again next summer. By having work done in late summer you can avoid the spring rush!

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