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Good Management Practices ( GMP's)for Scheduling Landscape Irrigation
The objective of the GMP's is to clarify an agreed upon process that compliments or gives a foundation to other generally accepted scheduling methods. Scheduling irrigation has regional and site specific attributes and precedes the final step of programming controllers.
Landscape Irrigation Scheduling ( IMDEC )
1. Inspect -Thoroughly inspect and evaluate each zone of the landscape irrigation system and make all needed repairs to insure proper head alignment, matched equipment in each zone, correct water pressure and optimum performance. Are the plants matched to your climate and hydro zone.
2. Measurements - Perform a Catch Can Audit by Irrigation Association or Texas AgriLife Extension guidelines and calculate the Precipitation rate (Pr) and Distribution Uniformity (DU) in each zone. Make additional repairs or adjustments to improve the Distribution Uniformity (minor equipment changes if necessary). Record location of water source and zone baseline water consumption especially for drip lines.
3. Determine Calculation Factors - Determine the proper factors to be used in the calculations such as; soil structure, crop types (Kc) , acceptable stress levels, along with other pertinent factors.
4. Evapotranspiration (Historical or Real-time) - Determine the historical or real-time Evapotranspiration numbers in inches as needed for the geographic location of the controller. Decide which numbers you will be using.
5. Calculate -Calculate the irrigation schedule based on plant needs, water delivery data, selected ETo and develop the weekly irrigation schedule for the year or season for each zone of the system then program controller in a manner to reduce water runoff.
Programming the controller (IPMAS)
6. Inspect - Inspect and correct the clocks: time, date, am/pm, back up battery, and zip code as needed. Insure weather sensors are in good working order and exposed to the elements.
7. Program - Program the calculated run time schedule (calculated from above methods) into the controller in a manner to reduce water runoff. Use cycle soak times or features if possible. Before entering the start days and times desired, inquire with the City for any requirements or restrictions. Schedules may be programmed weekly, monthly or yearly depending on the controller and schedule method.
8. Monitor - Monitor the landscape plants and real time ETo and make adjustments as needed. Check soil moisture with probe or sensor whenever possible. Monitor performance data if the controller provides such information. Check mainline for leaks by pressure loss or meter movement. Are insects or other pests present causing plant health issues?
9. Adjust - If the irrigation controller is not weather responsive than make incremental changes to correct deficiencies. One time watering events may be needed to zones to correct water deficits in those areas.
10. Secure & Conserve - Set to controller auto position; close the door to the controller and lock if possible to prevent unintentional changes to the program.
Scheduling landscape irrigation is not a static one time event. The process must involve the end user to determine their expectations and inform them about the relationship of irrigation water and plant health. If the client will agree not to supplement 100% of ETo during dry periods those areas can be calculated with a lower Quality Factor (QF) which will result in higher stress (wilt) during dry periods. Existing plants can be identified for their sensitivity to sun exposure or high water demands. This will be helpful in future replanting decisions that will result in lower water consumption. Proper water pressure at the emission device and no water puddles or lateral water movement ( run off ) remain the gold standard for landscape irrigation scheduling.