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UF/IFAS Extension Irrigation Best Practices: Calibrating and Scouting for Maintenance
- 1. UF/IFAS Extens ion Irrigation Best Practices Calibrating & Scouting for Maintenance
- 2. “quality landscapes that conserve water, protect the environment, are adaptable conditions, and are drought tolerant.” Florida Statute 373.185 Florida-Friendly Landscapes TM
- 3. Presentation Objectives By the end of this training, you will be able to: • Identify why irrigation maintenance is vital • Detect common irrigation issues • Design & conduct a catch can test • Calculate irrigation rates & uniformity • Recommend corrective actions
- 4. Why is irrigation maintenance vital? Pair & Share.
- 5. Groundwater Withdrawals vs Aquifer Recharge Balance is key to keeping water a renewable resource In many areas of Florida, the rate of groundwater withdrawal has been exceeding the rate of aquifer recharge.
- 6. Saltwater Intrusion Affected by many factors, including: • Rainfall levels • Withdrawals • Recharge • Sea level
- 8. 75% Percentage of US residential water use applied outdoors 2-3 times plant needs Amount of over-watering by homeowners
- 9. Scout to Help Out Role Play – count out groups of three
- 16. What other irrigation issues have you seen? Discussion.
- 17. Uniformity and rate of irrigation are key to… • Keeping plants healthy • Conserving water • Avoiding stormwater runoff • Minimizing erosion • And more!
- 18. Catch Can, You Can! Calculate uniformity & rate Measure water captured Place catch cans & apply water Assess site - Mary Brogan Park
- 19. DU = Vlq / Vavg Vlq = Summed volumes of the lowest ¼ of cans / # of cans in the lowest ¼ Vavg = Vcan1 +Vcan2+Vcan3… / total # cans A report card on how uniformly your irrigation is being delivered to plants. Average catch of lower quarter. Average catch overall. Distribution Uniformity (DU)
- 20. DU = 1.00 Acceptable DU levels Factors affecting DU Perfect uniformity. The entire area receives the same amount of water. Rotary sprinkler 0.55 – 0.65 Spray sprinkler 0.45 – 0.55 Pressure, nozzle spacing, system condition, nozzles. Distribution Uniformity (DU)
- 21. PRnet = 3.66 x Vavg / tR x ACD Vavg Amount of water (in/hr) that actually reaches the landscape, after losses between nozzle & landscape. Average catch volume (mL) Net Precipitation Rate (PRnet) ACD Area of catch device throat (inches2) tR Testing run time (min)
- 22. Turf Basic Rule of Thumb Adjust Seasonally Use Available Irrigation Scheduling Tools Apply ½ to ¾” per week, when 30-50% of turfgrass shows signs of wilt. Irrigation frequency and amount should be defined by evapotranspiration, soil water-holding capacity, and plant root zone depth. Tools take into account ET, rainfall, and other factors. UF/IFAS Irrigation Guidelines
- 23. Ideal Run Time (lower boundary) Upper Run Time Boundary Use your system’s PR (gross or net) to determine how long irrigation would have to run to deliver a set amount of water. Use the Scheduling Multiplier (SM) to see how much you would need to increase the run time to adjust for lack of distribution uniformity. Calculating a Simple Schedule
- 24. SM = 1 / 0.4 + (0.6 x DUlq) Ex: plants need ¾” water per week & DUlq is 0.55 Estimate of the additional amount of water required to achieve an acceptable appearance. SM = 1 / 0.4 + (0.6 x .55) = 1.37 0.75” x 1.37 = 1.03” water should be applied Focuses on avoiding stress to under-watered areas. Scheduling Multiplier (SM) Ex: takes 48 min/wk to deliver ¾” water, with SM = 1.37 48 min x 1.37 = 66 min of watering per week recommended
- 25. FAWN Urban Turf Irrigation App Provides recommended adjustments to irrigation schedule, based on weather station data. https://fawn.ifas.ufl.edu/t ools/urban_irrigation/ My Virtual Lawn App Allows you to compare how differently controlled irrigation systems would perform in your landscape. http://irrigationtool.appspot. com/
- 26. 7,942 – 15,884 Gallons of water saved per 1,000 sq.ft. per year by calibrating sprinkler system to deliver ½” or ¾” instead of 1” of water $240 Cost to implement this change
- 27. 12,707 Gallons of water saved per 1,000 sq.ft. per year by using UF/IFAS recommendations and calibrating sprinkler system to replace 60% ET instead of 100% $240 Cost to implement this change
- 28. Making Every Drop Count For more information and resources, check out these EDIS topic areas: https://edis.ifas.ufl.edu/topic_landscape_irrigation https://edis.ifas.ufl.edu/topic_series_florida_turfg rass_irrigation_requirements
Editor's Notes
- Before we start, I want to thank you for starting this journey of becoming Master Gardener volunteers. Throughout your training this spring, you are learning all about the 9 principles of FFL. Who can tell me some of the principles? What is the purpose of FFL?
- This is the definition of FFL from the FL Statutes. You can see that a major focus of FFL is to conserve water and protect the environment. So you are really becoming certified as educators and stewards of our water resources. At the same time, you live in the community and deal with the same difficulties as your neighbors. So you have a really well-rounded vantage point. You are increasing your awareness of best practices for irrigating, fertilizing, etc, but you are also able to relate to those around you in the community who struggle to learn the best ways to approach landscaping and then struggle to implement those practices. By implementing what you can and sharing your story, you can inspire others!
- Go thru contents of their folders & presentation objectives Handouts include: FAWN Fact Sheets on application rates, rain sensors, etc. Local watering restrictions in our area EDIS Publication SL384
- We want to use the right amount of water. Over- or under-watering can result in: Increased plant diseases and weeds. Shallow and weakened roots. Nutrient runoff or leaching. Saltwater intrusion (due to excess water use) Wasted water. Irrigating too much wastes money too: Water costs Cost of dealing with excess runoff & non-point source pollution Maintenance must include adjusting the irrigation schedule, because plants’ water needs vary over time recent plantings vs. established vegetation seasonal changes affect plant water needs
- Water Conservation Overall, water withdrawal data collected every five years by the USGS shows that total freshwater withdrawals in Florida have been decreasing. However, water conservation efforts and reductions in water withdrawals are still important, especially as we continue to grow in population. In parts of FL, the rate of groundwater withdrawals has been exceeding the rate of aquifer recharge, and this has caused reductions in groundwater levels. For example, excessive withdrawals have reduced pressure in the Floridan aquifer system, which has affected our springs. The average spring water flow in Florida has declined by 21 percent (Knight and Knight 2014). Excessive withdrawals from our aquifers have also been linked with saltwater intrusion; this negatively affects our water supply. Some regions of FL are classified by the state as "water resource caution areas“, where there are now or will be critical water supply problems within the next 20 years. Water conservation is a priority for state and local government, and we need to raise awareness among citizens as well. Source: https://edis.ifas.ufl.edu/fe943
- The Process of Saltwater Intrusion: The figure above shows how saltwater intrusion can occur. Where fresh groundwater and saline groundwater meet is called the freshwater/saltwater interface. As the aquifer is recharged inland, it flows toward the coast and prevents saline groundwater from coming inland. However, if we pump too much water out of the aquifer system, saltwater interface can migrate landward, and we then have “saltwater intrusion”. If we have a well near the freshwater/saltwater interface, saltwater contamination in the well can occur. Source: https://www.usgs.gov/media/images/process-saltwater-intrusion
- Map source: https://www.sfwmd.gov/documents-by-tag/saltwaterinterface Saltwater intrusion With saltwater bodies on both sides of FL, we have potential for saltwater intrusion into our fresh groundwater supply on both coasts. Being more dense than freshwater, saltwater is exerts a constant pressure to infiltrate the porous aquifers. If water is pumped for our use at a rate faster than the aquifer is replenished, the pressure of freshwater over saltwater in the land mass is decreased and intrusion can occur. Saltwater intrusion is worsened by drought periods when rainfall isn’t sufficient enough to replenish the freshwater aquifers. So, our local and state governments have to pay careful attention to well location and pumping rates, and we have to do what we can to conserve water. Source: https://edis.ifas.ufl.edu/fe757
- Approximately 75% of US residential water is used outdoors (Brehm, Pasko, and Eisenhauer 2013), and over half of the residential outdoor water use is for landscape irrigation (or roughly 9 billion gallons per day). (EPA 2016). Source: https://edis.ifas.ufl.edu/fe996 Haley et al. (2007) found that overall, homeowners over-watered as much as 2-3 times the amount their plants really needed, based on climate. (Source: p. 4 of ENH1114) Why does this happen? Because we don’t do great with calibrating or maintaining our irrigation systems. And we don’t always know how much to water or how to deliver the right amount of water. So let’s look first at some common irrigation issues that require maintenance. Side note: SUMMARY OF 2017 ESTIMATED WATER USE “The total amount of water withdrawn from groundwater and surface water resources in 2017 within the District was approximately 2,629 mgd (Table 8). The two largest water use categories were AGR and PWS, using 1,076 mgd and 1,084 mgd, respectively. These two categories constitute 82 percent of the total water use. Of the total use, 988 mgd (38 percent) came from surface water and 1,640 mgd (62 percent) came from groundwater sources (Figure 8)”. Source: https://www.sfwmd.gov/sites/default/files/documents/2017_est_water_use_report.pdf
- Count out into teams; 5 teams of 3 approx. Roles – 1) MG; 2) landscaper, neighbor, HOA, or other; 3) observer/time-keeper Role play presenting issue as MG. Then discuss!
- Broken line or nozzle Solution: repair line or replace nozzle
- Water over-spray or runoff (regular occurrence judging by staining) onto driveway. Also, trash pile on top of storm drain Solution: change out nozzles (quarter-spray instead of half spray), adjust rotor arc, place trash elsewhere on property
- Trying to use rotors to water grass on both sides of sidewalk, resulting in watering of impervious sidewalk and road. Applying too much water at once, leading to runoff. Solutions: calibrate and adjust sprinklers and scheduling to avoid over-watering, re-plant narrow strips of grass with low-maintenance groundcover so less water needed after established, replace narrow strip of grass to right of sidewalk with mulch, re-vamp to low-volume irrigation, etc.
- Nozzles missing! Solution: replace nozzles
- Irrigation uniformity issue. Foreground only receives water from one sprinkler, because on edge of driveway. Solution: Catch can test to determine uniformity and calculate scheduling multiplier; or, retrofit to add more emitters.
- Head-to-head coverage is best
- So, we have seen how scouting of irrigation function can help identify issues. And we have seen how the uniformity and rate of irrigation can affect runoff and plant health. Now we are going to do an activity, where we measure the uniformity and rate of our irrigation and compare it to UF/IFAS recommendations!
- It’s called a catch can test. Have any of you done one of these? In field, we will view testing of and discuss rain sensors, look at basic irrigation controller, and conduct catch can test.
- When return to class, have someone use xls to enter all can volumes and sort by amount. Use excel to sum the lower quarter and total volume collected. Then have class calculate averages and complete formulas in slide.
- Calculate PRnet for site and explain what it means – this is the amount of water actually being delivered to the landscape surface. Between nozzle and landscape can include drift, evaporation, etc.
- So now, we are going to use our calculated Prnet, along with a scheduling multiplier, to calculate a simple irrigation schedule. There are other, more accurate ways of developing a schedule, like the “Designated Watering Days Schedule” (see back of worksheet) or “Scheduling based on soil moisture”. You can also use online tools, like the FAWN Urban Turf Irrigation App.
- Calculate SM using the worksheet provided. Discuss examples in slide
- Here are a couple of resources to help with irrigation scheduling, as well as evaluating the water savings of different improvements to your irrigation system.
- So how much of a difference can irrigation calibration and improved scheduling really make? Well, here are some estimates from UF of water savings associated with irrigation calibration. Source: EDIS publication, Estimated Water Savings of Florida-Friendly Landscaping Activities (AE515)
- Source: EDIS publication, Estimated Water Savings of Florida-Friendly Landscaping Activities (AE515)
- Thank you for taking the time to learn these concepts, practice troubleshooting and relaying information as a MG, and practice calibrating an irrigation system. I hope you will use the tools and techniques you’ve learned today – try out the irrigation apps, scout your own irrigation system, calibrate and create a simple schedule for your irrigation system, etc. I will check back in later this year, to see how all is going and to see if you may have had a chance to use some of the practices we discussed today.