Performing A Greenhouse Water Audit

1. Performing A Greenhouse Water Audit By Paul Thomas, and Forrest Stegelin, The University Of Georgia Cooperative Extension Service

2. Adverse Water Use Legislation Is Inevitable • 1). 27 counties in Georgia currently have year-round water • restrictions in place that limit landscape watering. • Birmingham, Alabama landscapers, greenhouse and nursery • owners are desperately trying to prevent city officials from • shutting down nursery’s and landscapers….again. • 3). Most of Florida is in a Stage 2 drought. Water tables are • dropping and water use legislation is popping up everywhere. • 4). California, Texas, Oregon, Washington and most other • western states have new and more extensive water use • legislation. You do not own water in these states…you pay • for the right to extract it.

3. Adverse Water Use Laws Are Preventable The drought is forcing legislators to take action. They are in a tough spot! They cannot control the weather, and yet answer to the citizens. They need facts to make the best decisions. The question is not “if” restrictive legislation is to be proposed at the local level, it already has been and will be again! If things don’t improve, it’s only a matter of time before national legislation is proposed that will limit water use for all farmers and growers. Doing nothing will result in legislators justified in their beliefs that they must act given what facts are known and what they see.

4. Why Do A Water Audit? The large volumes of irrigation water used, and the high visibility of our industry, puts our industry at risk of losing control over our water resources. Worse, our industry is being viewed as a major water waster! Legislators want to know how much water we use, so they can assess if steps need to be taken…but we have no clue! Our lack of interest greatly concerns the people who regulate water usage in our state. We must become pro-active.

5. Our Image? What Can We Do?

6. Will A Greenhouse Audit Really Help? Yes, The greenhouse industry is probably the most efficient water user group of all commodities in agriculture. The greenhouse industry is efficient compared to car washes and industrial firms. The trouble is, we don’t have the proof. What proof? Facts! Figures, Ratios, Comparisons! Water conservation documentation – Drip tubes, etc. Gallons of water per dollar of tax revenue generate. Gallons of water per square foot / acre / year. Gallons of water per dollar wholesale “farm-gate” value. We need to get this information soon!

7. Water Audit Procedures Carefully audit (measure), review and then document commercial water use in your operation. Identify potential problem areas, and then explore methods to improve water use efficiency. Develop short and long term management tactics to reduce water use.

8. Water Audit Procedure The following are some important questions you should ask. Once answered, develop a summation of your findings, and document all the improvements you made. This information will help you explain your water use policy and use history to legislators.

9. What’s In A Water Audit? Audit Information: Current “Best Management Practices” (BMP’s). Crop inventory organized by water need. Pesticide and chemical inventory. Expansion, storage and recycling options. Water conservation technology implemented.

10. Goals Of A Water Audit Reduce luxury water consumption! Eliminate non-target water use (waste). Reduce current fertilizer and pesticide usage. Minimize legislative problems through consistent education efforts. Restore legislator’s confidence in our water use policies, and our industry.

11. The Audit Greenhouse Water Use Is Different Than Field Agriculture

12. Part 1. Water Source Assessment  ________________________________ Do you have multiple sources of water? Do you store water for emergencies? Do you have a “manditory water restriction” plan? How long can your operation do without water? What would be the financial loss if water was cut off?

13. Is Your Water Source and/or Pump Capacity Up To The Challenge? If your pump provides only 30 gallons per minute (GPM), you can easily see that it will not be capable of irrigating a large field of perennials and eight greenhouses at the same time. You would likely have to water one house or one zone at a time. A member of your crew would likely be watering all day, most days. Your pump would run all day, every day. Hot weather labor costs would skyrocket!

14. What If Things Were Different? ? If you had that one day’s supply of water stored in a 30,000 gallon storage tank…. with a distribution pump, and a capability to deliver several hundred gallons per minute… and you automated the delivery system….. and used efficient drip irrigation or ebb and flow benching…. …..you could water your entire facility in a few hours for just pennies in labor !!!

15. The Solution: Water Storage! YES! You can! At 30 GPM, would you have enough water replaced in the storage tank each day to allow full watering schedules? If we assume the pump cycles on 45 minutes per hour, then 45 x 24 hours in a day = 1080 minutes. At 30 gallons per minute, we would have 32,400gallons of water pumped per day. If watering was automated, you’d save the labor cost, and complete all your watering in a few hours. If you had a three day supply, you’d never have a direct use shortage, and you may use less electricity as the tank would rarely be drawn down and require a full day of pump activation. The labor savings would be significant!

16. Part II. Water Use Assessment and Storage Do you know your greenhouse operation’s maximum daily water demand in summer? Do you know your greenhouse operation’s maximum weekly, monthly or yearly water usage – in cubic feet or gallons? Do you know your greenhouse operation’s maximum daily water demand? Do you know which crops have maximum daily water demand?Which have the least?

17. Part II. Water Use Assessment and Storage There are three basic methods to determine water usage over time! 1. Endpoint Flow Rate 2. Volumetric Calculations 3. Flow Meter Reading

18. Flow Meters Are Your Best Choice! Accuracy Continuous Measurement Data Acceptability Is Good Low Maintenance / Permanent Low Long-term Cost Simple To Install

19. An In-Line Flow Meter

20. And easy to read:

21. Part III. Water Use Labor Cost Assessment Are your employees watering efficiently? Do you periodically observe your employees watering skills? Do you know how much the application of water is costing you per hour? On what basis do you decide to water? Need? Schedule? Do you have a daily time period set to water within?

22. Part III. Water Use Assessment Do you record daily, weekly or monthly water use? Do you test your water quality on a monthly basis? Do you keep the results of your water tests to show the absence or presence of ground-water contamination

23. Knowing True Costs Can Generate Significant Savings You can save up to 70% of water used for pot crops and 35% for bedding plant production by updating your watering system to include drip irrigation, ebb and flow benching or flood floor systems. Automation would save hundreds of hours / month. The estimated labor savings is significant. If you pay the average of $8.40 / hour, you can save just over $7300.00 per Quonset house or large bay per year.

24. Part IV. Application Technology Do you know if your pressure is correct for that particular system component? Do you have particle filters and properly calibrated injectors or proportioners? When did you last test the system? What percentage of your total crop “variable cost” does watering take up?

25. Back-Flow Prevention Selection: Back-flow prevention is the law in Georgia! Are you connected to a municipal water source controlled by a water authority? Pumping from a well? Pumping from a stream? Do you or any neighbors live within a mile of the greenhouse? How are you applying the water? Using drip irrigation? Injecting fertilizer, pesticides or chemicals? If so, you are required to have a back-flow prevention system

26. Back-Flow Prevention Guidelines: Consult with the Local, State, County or on some cases the Federal agency that may monitor water quality and safety. They have specific guidelines as to the type of back-flow prevention needed. However, if you are connected to a local water authority (LWA), their rules supersede all others. If the State requires only a single stage check valve and the water LWA requires a double check reduced pressure device, you must go with the more expensive LWA requirements. The most effective and cheapest back-flow prevention measure is a 12” air-gap between the top of a storage tank and the incoming water line. Water can’t jump up-hill in open air!

27. REDUCED PRESSURE ZONE BACKFLOW PREVENTERS PROS: ·   Two IN-LINE INDEPENDENT CHECK VALVES with intermediate relief valve . ·    For use in hazardous CROSS-CONNECTION situations. ·    If both check valves fail, BACK SIPHONAGE IS DIVERTED TO THE ATMOSPHERE.

28. REDUCED PRESSURE ZONE BACKFLOW PREVENTERS ·    They have low pressure drains incorporated into their design. ·    Test port cocks are provided for testing back siphonage. ·    Can be installed below irrigation sprinkler head,. CONS: ·   Expensive in the SHORT RUN ·    Must be installed one foot above the ground.

29. Part V. Water Recycling Do you recycle any portion of the water used in your growing operation? Can you accurately measure the amount of recycled water? Could you report with some accuracy how much water you saved per year by recycling? Have you attended a water recycling lecture or meeting in the last year to update your understanding of the new technology, standards and methods being used?

30. Water Collection There are many ways to recycle water, but all systems require you to plan on how you will Collect and reuse or of the water. Cisterns, and ponds are suitable for large or small operations. Getting the water to that holding are can be a challenge. Drainage Channels Holding Ponds

31. Storage Tanks and Cisterns

32. Table 4.0 – Rainfall In Georgia Month Average Rainfall January 4.0 February 4.0 March 5.0 April 3.0 May 4.0 June 3.0 July 3.0 August 3.0 September 2.0 October 2.0 November 3.0 December 4.0 Potential Rainfall

33. Table 1.0 Greenhouse Rainfall Recapture Potential If you collect rainwater as a supplemental source, the gallons add up to significant savings. Roof Size in Square Feet Rainfall in Inches 0.25 0.50 0.75 1.00 2.00 3.00 4.00 5.00 6.00 1000 140 281 421 562 1124 1685 2247 2809 3371 1100 154 309 463 618 1236 1854 2472 3090 3708 1200 169 337 506 674 1348 2022 2697 3371 4045 1300 183 365 548 730 1461 2191 2921 3652 4382 1400 197 393 590 787 1573 2360 3146 3933 4719 1500 211 421 632 843 1685 2528 3371 4214 5056 1600 225 449 674 899 1798 2697 3596 4494 5393 1700 239 478 716 955 1910 2865 3820 4775 5730 1800 253 506 758 1011 2022 3034 4045 0566 067 1900 267 534 801 1067 2135 3202 4270 5337 6405 2000 281 562 843 1124 2247 3371 4494 5618 6742 2100 295 590 885 1180 2360 3539 4719 5899 7079 2200 309 618 927 1236 2472 3708 4944 6180 7416 2300 323 646 969 1292 2584 3876 5169 6461 7753 2400 337 674 1011 1348 2697 4045 5393 6742 8090 2500 351 702 1053 1405 2809 4214 5618 7023 8427

34. Capacities of Various Sized Cisterns Diameter of Round Type DEPTH 6 8 10 12 14 16 18 6 1266 2256 3522 5076 6906 9018 11412 8 1688 3008 4696 6768 9208 12024 15216 10 2110 3760 5870 8460 11510 15030 19020 12 2532 4512 7044 8532 13812 18036 22824 14 2954 5264 8218 11844 16114 21042 26628

35. Part VI. Water Release - Pollution Prevention Do you know how much water you are releasing from your operation? Do you have a bio-remediation site (a catch-pond with established plants such as cattails) to reduce free nutrients and act a s a bio-filter prior to releasing the water. Do you have a scouting or evaluation program to monitor water release quality and quantity Do you know the acceptable limits for nitrate or phosphorus release in your local community or water district?

36. Part VII. Monitoring water use legislation and local water use regulations Do you know if your county or city has a commercial water use ordinance? Are there water use restrictions in effect in your community? Is your region currently in a drought or low-water supply situation? Have any operations near you been asked to conserve or cease watering use due to a municipality shortage?

37. Part VIII. Planning For Future Expansion Do you have a site-specific water use fact sheet for local legislators or regulatory personnel to inspect upon demand? Is your growing facility within 5 miles of a subdivision or city? Are you familiar with your state regulations regarding water release, well contamination and groundwater contamination?

38. Part VIII. Planning For Future Expansion Is your current water supply sufficient for your potential expansion needs over the next ten years? What are the impediments to expanding your water supply?

39. Part VIII. Planning For Future Expansion Could conservation and new technology negate the need for a new well or expanded usage? Would you consider changing crops grown to include more drought tolerant plants. Would changing over to a water efficient application method pay for the new well or additional water source costs in the next five years?

40. Automating Your Irrigation System Is a Great Investment! Automating your irrigation system proves to be a very good investment. Payback (breaks even) for $4778.00 is under 1 ½ years with 79% return on investment; @ 6% interest over 10 yrs, this is greater than a $22,000 net present value, or a 65% internal rate of return with a benefit cost ratio of 5.8. That is a fantastic benefit ratio. Net labor savings is over $3,712 per house over the next 10 years !!!!! .

41. Automating Your Irrigation System Is A Great Investment! Non-monetary tangible benefits: More uniform plant growth, Scarce labor now freed up Labor for planting or loading trucks, Hire less staff More management time for planning! Don’t forget the real conservation benefit of using between 30% and 70% less water ….and the public relations benefit gained by being efficient and aware!

42. Read Your Greenhouse Water Audit Handout If you have questions, The University of Georgia has faculty that specialize in Irrigation Technology, Crop Production, Agricultural Economics, Regulatory Compliance and Environmental Assessment. See your county agent to access these resources.

43. Acknowledgments: The author would like to thank Ben Bradshaw, Progress Growers Inc, Dr. Don Wilkerson, Texas A&M University, Dr. Maryann Rose, formerly at The Ohio State University, and Dr. Tom Yeager, University of Florida for the use of their previously published materials, tables and figures.