Tune up Landscape Irrigation

Allen D. Owings, Koske, Thomas J., Sheffield, Ron

Collectors can be used to check coverage and inches-per-hour output.

Irrigation programmer.

Today's high tech irrigation systems demand even more attention so you can receive all their enhanced benefits. Systems must be programmed to fit the location’s needs and those of the current season. Adequate soil moisture is essential for a thriving landscape. It can mean preventing the loss of newly planted grass or increased diseases.

Irrigation should be set to run in the early hours of the day. Morning water pressure is usually better, and foliage will have time to dry before the evening dew or afternoon showers set in. This dry evening segment will reduce the infectious period of diseases and help reduce that problem.

Check head output and uniformity with water collectors like tuna fish cans. Place several collectors around, and check coverage and inches-per-hour output.

One approach to irrigation management is to set the timer for what you guess the zone may need; then watch the results. If your needs are just to protect from general plant loss, an on-call approach or weekly irrigation can do the job.

For best water management, the irrigation factors should be incorporated into your program. They are soil type, current drought conditions, sunlight, types of plants, slope and wind.

Soil types have a lot to do with irrigation cycles. Clayey soils require several short, back-to-back cycles because those soils need more water at any one time, but water can only infiltrate slowly. When well-watered, clay lawns have the capacity to supply moisture longer. Sandy lawns take in water easily but have a lower capacity to hold much water. They need more frequent and shorter-cycle applications. Head output should complement the soil's infiltration rate and be a factor in the original design, but you can still best manage whatever equipment you have.

The plant materials in the landscape also affect irrigation. Some materials have deep roots and drought resistance. These materials need not be watered as often as shallow-rooted species and succulents. It would be best to plant similar materials together and allow for more appropriate irrigation in zones instead of all zones getting the same dose.

When in droughty periods during the hot season, water more frequently. Instead of once or twice a week, you may need a third watering. Poorly designed systems will suffer more in drought and will definitely need more irrigation time to make up for their lack of effectiveness.

If you have slopes, it is important to zone the higher areas differently from those that are lower. High spots will need more frequent watering and low spots or downslope will collect water from upslope and need less irrigation to avoid disease and root loss. You may adjust run times or the frequency and timing of their cycles to get the appropriate dose for the site.

Shady areas usually do not need as much water, but that depends on the type of plant materials. Contractors should consider this in their designs. You should base these zone needs on the site conditions and plant material needs.

Wind changes everything. It changes the spray patterns and thus the uniformity of coverage. It also accelerates the evapotranspiration, which causes the soil to dry out more and plants to lose more water. Many areas have the reverse of this problem and have dead air space because of walls and larger shrubs, etc. Consider this aspect of the site when allowing for irrigation programming.

Full automation is far from foolproof. Irrigation needs and cycles should be re-evaluated monthly to locate problems and adjust for changing needs. A properly designed and operated irrigation system will ensure that the critical factor of soil moisture will be there to sustain healthy plant growth.

7/13/2005 6:05:04 PM
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