Effluent water has positive potential
Golf courses are by far the leading recreational turfgrass users of wastewater. The reasons are simple: golf courses have intensively managed turf, they have managers with a high level of professionalism, and they require significant amounts of water. However, with the appropriate knowledge, other managers of large turf areas can take advantage of the benefits wastewater use offers.
The use of wastewater-also called effluent water-on turfgrass areas is currently a politically correct thing to do. Many environmental groups that ordinarily oppose "wasting" water on large turf areas support this use of effluent water. Why? The main reason is that this water is no longer wasted. Plus, turf utilizes nutrients in the effluent, reducing potential pollutants. Also, according to James R. Watson's Waste- water Reuse for Golf Course Irrigation, most turf areas have relatively permeable soil-a 3- to 4-foot depth of soil is adequate to cleanse, purify or reclaim wastewaters.
Generally, we evaluate water in terms of its mineral and biological components. We then classify it based on its intended application. You can find numerous sources that classify plants with respect to their tolerance of, or sensitivity to, salinity and specific mineral toxicities. Such sources help identify which plants thrive with wastewater irrigation.
Making these types of plant selections is important because most grounds managers don't have a choice in the quality of water available for their site. And, the growing trend by city governments to mandate that large sites use only recycled water is further reducing many grounds managers' choices of water quality.
The simple fact is that if a given soil is irrigated with a given water over an extended time, the soil assumes the characteristics of that irrigation source. Most of the problems encountered with irrigation water are associated with the direct and indirect effects of some specific compounds: excess total salts (TDS), excesses of specific mineral ions (sodium, boron, chloride, etc.) and excesses of bicarbonate, which contribute to elevated (alkaline) pH. Understanding how these minerals affect your turf can help you better manage it and take advantage of effluent water.
Take the tests In our quest to understand effluent use, it is imperative to know the condition of the soil and the mineral makeup of the irrigation source. Your first step, then, should be an irrigation-suitability test. As a grounds manager, you are interested in testing for the elements that affect or impact turf quality. Therefore, look for an irrigation-suitability test that includes the following minimum test standards: * pH * Conductivity * Calcium * Magnesium * Potassium * Sodium * Iron * Alkalinity * Carbonate * Bicarbonate * Hydroxide * Chloride * Sulfur * Boron * Total salt concentration.
For effluent water nutrients, also request analysis for: * Phosphorus (P) * Total Kjeldahl nitrogen (TKN) * Ammonia-nitrogen * Nitrate-nitrogen.
Helpful formulas and ratios the lab should figure for you: * Sodium adsorption ratio (SAR) * pHc * Adjusted SAR * Total cations and anions.
To collect enough water for irrigation purposes, it is common for large sites such as golf courses to use several water sources, such as well, city, surface drainage, river and effluent. It is important to sample each source individually. Also, take one composite sample directly from the irrigation head, after it has run at least 10 minutes to flush all stagnant water from the line. Doing so will ensure that you perform your test on a representative sample of the water with which you're irrigating your turf. It is also important to sample throughout the year to check for variations. Most waters change over time, and some will change significantly due to seasonal demands on the water table.
A good soil test is of equal importance. The soil test helps determine the levels of critical elements. It also helps indicate the quantity of any one type of irrigation water the soil can filter before you encounter significant problems. It is extremely important that you include sodium in the test. Some labs-but not all-include this in their standard package. Sample each individual area of your property. Typically, greens, tees and fairways may have different soil types and different concentrations of harmful elements.
Take a road trip We're not talking about traveling to some exotic destination. Instead, visit the source of your irrigation water-the sewage-treatment plant. Because many different types and levels of effluent processing exist, investigating your source can give you real insight into uses for the water.
Treatment plants range in size from community-wide facilities to giant municipal facilities that process millions of gallons of wastewater per day. Find the facility that serves your site, call the plant manager, ask to take a tour and have him or her explain the process to you. Learn what variations can affect the output of the treatment process, such as: * How much industry is involved in the waste stream and how does it affect overall quality? * In a seasonal-population area, how does the fluctuation of tourists affect the variation in amounts processed per day?
To receive effluent water, many large sites must agree to use a minimum gallonage per day, week or month. Find out what your municipality expects of you and develop a contingency plan should an extended rainy period set in.
Many plant operators have told me nothing is wrong with their water. "See?" they say. "It fits all the regulatory-discharge specifications." In those cases, you need to help them understand that your criteria for irrigation suitability are very differnt from their discharge standards. Once you explain your needs, your plant manager might even be able to modify the process to give you a more suitable water for your irrigation requirements. Another resource the plant operator might share with you is his or her water-testing records. These can be a great source of monthly testing results, which can help you monitor seasonal changes-for a very low cost or even for free. If you gain nothing else out of the hour spent, you will at least let the plant operator know you are interested in what is going on at the plant and are concerned about the final product you will receive.
What is important? After you receive the results of your water tests from the lab, you need to prioritize the data into what affects you most. You can break down the components of water quality into five main areas. (See the table, "Components of water quality," opposite page, for more details on each component.)
Problems that occur on sites with high soil salinity are compounded with a highly saline irrigation source. These problems are usually not uniform across the site but occur sporadically. A high level of soil salinity can reduce or delay seed germination and seedling development. On established turf, the first sign of a salinity effect is a blue-green- or purple-colored turf similar to the color of drought-stricken grasses. You'll typically encounter salinity problems during periods of heat or drought stress. This occurs because the turf's demand for water is high during this time. The high salt content of the soil solution reduces plants' water availability. High demand by the turfgrass, coupled with reduced water availability due to salts, causes drought-like conditions. This is compounded by the fact that it is hard to leach excess salts from soil during periods of high temperatures and limited rainfall.
Develop your management plan If you have worked through the water test and found your irrigation water falls outside several of the acceptable ranges, the water may still be suitable for turfgrass irrigation. A few suggested alternative management practices are: * Plant salt-tolerant grasses. Not all grasses perform equally under the same conditions. When selecting grasses, pay close attention to the E.C. tolerance of the proposed plant vs. the E.C. of the irrigation water. * Improve drainage. Any additional tools that you can use to add aeration, reduce soil compaction and improve percolation may be beneficial in removing harmful salt concentrations. * Leach excessive salt. Exceeding the leaching fraction will carry dissolved salts through and out of the zone. * Acidify irrigation water. The addition of acidification agents, such as pHAIRWAY-brand product or sulfuric acid, causes the soil sodium to more easily leach from the soil profile and neutralize the bicarbonates from the water and soil. This frees up available calcium, forms better soil structure and increases water percolation. * Correct the soil balance. Carefully consider the base-saturation percentages on the soil test. In poor-quality water, the reduction of available calcium and magnesium is critical. You must replenish it as required. * Consult an expert. Seek the advice of your peers who are successfully dealing with effluent water or obtain the services of a qualified water-quality specialist. Both can help you manage the details of your overall program. Dealing successfully with an effluent-irrigation source can be a reality. It is essential to "plan your work and work your plan." By removing many of the "unknown" elements from the overall equation, it is possible to make good use of water that has been under-used in the past.
Steve Ninemire is president of the 9Mire Group (Prosper, Texas). He can be reached at (972) 346-2522.
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