CITY OF MANSFIELD STORM WATER MANAGEMENT
IRRIGATION
How Does Irrigating Lawns And Landscapes Affect Stormwater?
Irrigation practices can significantly the quality of water in local waterways. The problem exists when too much water is applied for irrigation purposes, or when water has been directed onto impervious surfaces, like roadways.
When too much water is used for irrigation, the water will eventually runoff the lawn or landscape and enter our local storm drainage system and waterways. Pesticides, herbicides and fertilizers applied to the lawn or landscape before irrigation will be washed off and enter the local waterways as well. The water quality problem with excess irrigation is not the water itself; the substances dissolved in the water on its way into our local waterways are the problems.
How Much Water Is Too Much?
Some plants require water, especially during the summer months, in order to survive. However, the amount of water applied to lawns and landscapes exceeds the amount of water required in many instances. Many times the water applied exceeds even the amount of water needed to keep the lawn or landscape lush and green. There several items in the marketplace for determining how much water is in your soil, and even how much water needs to be applied. There are also many low-tech ways of determining these values.
A recommendation is to apply 1-1.5 inches of water to your lawn or landscape at a rate that does not lead to runoff. This can be monitored using a rain gage, or even tuna can, to determine the amount of water applied. Observing the area for signs of runoff while watering will help determine if the water is being applied at a rate that exceeds its ability to absorb the water. This recommendation is for watering during summer months in order to maintain a lush and healthy lawn.
One of the most important features to consider for proper irrigation is the ability of the soil to absorb the amount of water applied. If water is applied to lawns and landscapes in the same volume, but in a shorter period of time, much of the water does not get the opportunity to soak in and runs off the area applied. While the plants may remain alive and green, this may result in shallower root systems that require more frequent watering than deeper root systems.
In periods of excess water, the root walls tend to be thinner, as well as shallower, to make it easier for water to enter. In periods of water scarcity, the root walls tend to become thicker and penetrate deeper, to ensure whatever water the plant collects is not released back into the soil. Watering only when the plant shows signs of a lack of water ensures the proper balance for the root wall structure. The signs of dehydration are different for different plants, but tend to include leaf curling or folding and yellowing of green areas.
Using proper irrigation techniques reduces the chance for excess irrigation flowing off of the lawn or landscape. By keeping irrigation water on your lawn or landscape, you are reducing the amount of fertilizers, pesticides, herbicides and other pollutants entering our local waterways.
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