Physical water conditioners for managing turfgrasses

The physical water-conditioning products tested in these studies did not consistently improve or remediate soil salinity or consistently make a positive impact on turf quality and root-zone salinity.

Two catalytic water conditioners and a magnetic water conditioner were tested. Irrigation was regulated separately for each water-quality unit and each water-conditioning unit.
Photos by T. Barrick

By Bernd Leinauer, Ph.D.; Ty Barrick; Matteo Serena; Marco Schiavon; and Bernd Maier
Read this story in GCM's digital edition

Physical water conditioners, also called “inline” water-conditioning devices (1) have been suggested by manufacturers to lessen the impact of reduced-quality waters on soil and plant stand quality. Physical or non-chemical water conditioners can be classified into different categories based on their working principles (1). Units that are currently used in turf maintenance include:

  • Magnetic or electromagnetic devices that apply a magnetic field from either the outside or the inside of a pipe to the water stream (for example, Magnawet)
  • Electrostatic precipitators that induce an electrical charge in the water; the charge can be applied directly by means of electrical power (for example, Zeta Rod) or as a hydroelectrical dynamic charge from water flowing along a metal pipe (for example, Aqua-PhyD)
  • Catalytic devices (for example, Care-Free, Fre-Flo, Zeta-Core) that provide a turbulent flow of water over an alloy core composed of certain metals (catalyst) that are reported to change the configuration of minerals in the water so they no longer accumulate or bind to surfaces
  • Ozone and oxygen treatment devices that inject ozone into water, creating hydrogen peroxide and nitric acid, which reportedly increase oxygen levels in the water.

The research study site was located at New Mexico State University’s golf course, where both potable and saline water were available for irrigation. The photo shows the construction of the irrigation system for the research project.

Scientific and unbiased information is lacking as to whether turf quality and soil salinity improve over a longer period of time when saline irrigation water is treated with non-chemical water conditioners. We conducted a four-year study at New Mexico State University in Las Cruces, N.M., to investigate the effects of magnetic, catalytic and hydroelectrical water treatment on perennial ryegrass establishment and quality and on soil chemical characteristics. The objective of the research was to determine whether permanent applications of physically treated irrigation water improve perennial ryegrass establishment and quality and affect salinity buildup in the root zone.

Effects of non-chemical water conditioners

Project site

The research was conducted at New Mexico State University’s golf course, where saline groundwater was available for irrigation. The soil at the site was a Torripsamment, a sandy entisol typical for arid regions. Monthly average temperatures, precipitation and reference evapotranspiration (ETo) at the research site are available in a previous publication (5). Climate data to calculate ETo were collected at NMSU’s weather station located on the golf course in close proximity to the study.

The research area measured approximately 246 feet × 65.6 feet (75 meters × 20 meters) and plot size was 20 feet × 20 feet (6 meters × 6 meters). Each treatment was replicated three times.

Water treatments and turf maintenance

Treatments consisted of two types of irrigation water and several water-conditioning products. Plots were irrigated with either potable water (electrical conductivity [EC] = 0.6 deciSiemens/meter, Sodium Adsorption Ratio [SAR] = 1.55) or saline water (EC = 3.1 deciSiemens/meter, SAR = 8.94) pumped from a saline aquifer near the research site. Saline irrigation water was classified as very high in salinity and medium for sodium hazard (7).

Conditioning treatments included two catalytic water conditioners, Zeta-Core (Zeta-Core USA Inc., Corrales, N.M.) and Fre-Flo (Fre-Flo Water Systems Inc., Santa Monica, Calif.); a magnetic water conditioner, Magnawet (Magnawet Corp., Indianapolis, Ind.); and a control treatment. In February 2007, a hydroelectrical treatment unit, Aqua-PhyD (Aqua-PhyD Inc., Irvine, Calif.), was added to the project. Physical water-treatment devices were mounted into the water supply lines, and irrigation was regulated separately for each water-quality and conditioning unit.

A photo of the study site in October 2006 after the first establishment period and the second growing season.

Overhead irrigation was applied by Walla Walla MP2000 Rotators (Walla Walla Sprinkler Company, Walla Walla, Wash.) operated at 30 psi (200 kPa), with one pop-up streaming rotor installed in each corner of a plot. Irrigation audits were conducted during each of the growing seasons to ensure distribution uniformity was never lower than 0.7 and to provide data necessary to schedule irrigation run times.

Water meters were used to record irrigation water use separately for each conditioning unit and for each water quality (saline or potable). Irrigation amounts were calculated every Monday morning based on the previous week’s cumulative ETo rate, and plots received a daily equivalent of one-seventh of the total weekly ETo.

Turf maintenance

The perennial ryegrass (Lolium perenne L.) cultivar IG2 was seeded on Jan. 20, 2005, and on March 13, 2007, at a rate of 6 pounds/(1,000 square feet) (30 grams/square meter).

On Oct. 10, 2006, the entire study area was sprayed with glyphosate herbicide to remove any existing vegetation so that a second establishment experiment could be conducted. The entire area also was irrigated with potable water from November 2006 to March 2007 to leach salts that had accumulated in the root zone during the first two years of the study. This ensured that there was no difference in soil salinity between plots irrigated with saline water and those irrigated with potable water at the onset of the second establishment experiment, as our data analysis confirmed.

The plots were fertilized with 15-15-15 fertilizer at a rate of 1 pound nitrogen/1,000 square feet (5 grams/square meter) before each seeding. A total of 10.2 pounds/1,000 square feet (50 grams/square meter) each of nitrogen, phosphorus (P2O5) and potassium (K2O) were applied in 2005 and 2007. Fertilizer applications were made approximately every 15 days during the first two months of establishment and every 30 days thereafter. Nitrogen was applied from 15-15-15 fertilizer at rates totaling 5.1 pounds nitrogen/1,000 square feet (25 grams/square meter) in 2006 and 4.1 pounds/1,000 square feet (20 grams/square meter) in 2008.

Irrigation

In 2005 plots irrigated with both saline and potable water received 80% ETo. From March through August 2007, plots irrigated with potable water received 95% of ETo, and plots irrigated with saline water received 110% ETo. From March to October in both 2006 and 2008, plots irrigated with potable and saline water received 75% and 110% ETo, respectively. The additional volume of water added to the saline-irrigated plots compared to those irrigated with potable water corresponded to the leaching fraction necessary to prevent excessive buildup of salt in the root zone.

The area was mowed with a rotary mower at a height of 2 inches (5 centimeters), with clippings returned. Weeds were removed manually during the entire four-year research period.

Data collection and analysis

A photo of the study site in November 2008 at the end of the four-year study testing the effects of non-chemical water conditioners on turfgrass quality and root-zone salinity.

Digital image analysis was used to assess stand establishment (3,6). Three pictures per plot were analyzed for green coverage and averaged for statistical analysis. Each image covered an area of 3 feet × 3.6 feet (0.9 meter × 1.1 meters). During the 2005 establishment period, photos were taken every two weeks in February and March and monthly from April to June. Establishment in 2007 was evaluated based on images taken on April 2 (18 days after seeding, May 2 (48 days after seeding), and June 19 (96 days after seeding).

Turfgrass quality was assessed by means of a visual rating scale of 1 to 9, recommended by the National Turfgrass Evaluation Program, where 1 = dead turf and 9 = dark green, uniform turf (4). Turfgrass quality of each plot was determined monthly from May to October in 2006, from May to July in 2007, and twice a month from March to November in 2008.

Aqua-PhyD, a hydroelectrical water treatment unit, was included during the last two years of this study.

Normalized Difference Vegetation Index (NDVI) readings were collected monthly from June to October in 2006 and twice monthly from March to November in 2008 to substantiate visual quality ratings. A Greenseeker (Trimble Navigation Ltd., Ukiah, Calif.) was used to take measurements at approximately 3 feet (90 centimeters) above the surface at a normal walking speed. NDVI values were recorded and stored in a data logger (8). The mean vegetation indices from each plot were calculated and used for further statistical analyses.

Salinity buildup in the root zone was determined on soil samples collected at depths of 0 to 4 inches (0 to 10 centimeters) and 4 to 12 inches (10 to 30 centimeters) in October 2005 and May and September in 2006. Soil samples at depths of 0 to 4 inches and 4 to 8 inches (10 to 20 centimeters) were collected in July 2007 and February, June, September and November 2008. Samples were subsequently analyzed for electrical conductivity, sodium and Sodium Adsorption Ratio (SAR).

Results

Turfgrass establishment

Data analyses revealed that neither water treatment alone nor any of the combinations of water treatment, water quality and days after seeding had a significant effect on perennial ryegrass establishment in either 2005 or 2007. However, irrigation with saline water significantly delayed establishment. At the end of both establishment periods, coverage by perennial ryegrass was greater in plots irrigated with potable versus saline water. It was also noted that saline irrigation led to an increase in root-zone salinity over time, which resulted in a slowed rate of establishment in perennial ryegrass (2).

Overall, turfgrass quality and NDVI values of perennial ryegrass were consistently lower when irrigated with saline water, except in summer 2006, when NDVI values did not differ between plots irrigated with saline water and those with potable water (data not shown). Water quality did not affect turf quality in 2006 and 2007.

Overall, water conditioning systems affected turfgrass quality in 2007 and NDVI in 2008 on some sampling dates, but treatments did not improve or decrease quality similarly throughout the investigative period. Quality differences between plots receiving different conditioning treatments were only apparent on one of the sampling dates (Table 1). Plots irrigated with water treated by Fre-Flo and Aqua-PhyD showed greater turf quality than control plots or plots irrigated with magnetically treated water (Table 1). In 2008, control plots and plots irrigated with Fre-Flo-treated water exhibited greater NDVI during the fall than all other treatments (data not shown).

Root-zone salinity

2005. In 2005, water conditioners had a significant effect on electrical conductivity, sodium and SAR in root zones of plots irrigated with saline water. Electrical conductivity was highest for the Fre-Flo and control treatments and lowest for the plots treated with Zeta-Core and Magnawet. Under saline irrigation, control plots also exhibited higher SAR and sodium content than plots treated with Fre-Flo or Magnawet.

The positive effects of water conditioners were not observed on plots that received potable water. On the contrary, whereas Fre-Flo and Magnawet treatments reduced SAR and sodium concentrations in plots irrigated with saline water, both water treatments resulted in increased levels of sodium and SAR in plots irrigated with potable water. Furthermore, although some of the salinity parameters measured in plots irrigated with saline water at the end of the growing period of 2005 may have been significantly different from one another, all of the measured parameters were well below threshold levels that are considered critical for cool-season turfgrass growth.

2006. No clear trend was observed for the salinity parameters measured in root zones in 2006. In May, electrical conductivity and sodium concentrations in control plots irrigated with saline water were lower than in plots that received conditioned water. However, in September, electrical conductivity values on the same control plots were the highest among all plots, but sodium concentrations were not significantly different from values measured on treated plots. (Table 2). Furthermore, unlike in 2005, water conditioning had no effect on electrical conductivity or sodium concentrations in plots irrigated with potable water (Table 2).

2007. In 2007, only irrigation water quality affected salinity in the root zone; however, water conditioning did not improve the chemical composition of the root zone.

2008. As observed in 2007, conditioning treatments had no effect on electrical conductivity values measured in 2008. Analysis of sodium data collected in 2008 indicated that, with the exception of the June sampling date, water conditioning had no significant effect on sodium concentrations (Table 3). In June, sodium concentrations in untreated plots were lower than in Fre-Flo-treated plots but did not differ from any of the other treatments (Table 3). Plots irrigated with magnetically treated water exhibited lower sodium concentrations than plots treated with Fre-Flo or Aqua-PhyD. Furthermore, water conditioning did not affect SAR values on plots receiving potable water throughout 2008 (Table 4). However, on plots irrigated with saline water, SAR was lower on control plots than on Aqua-PhyD or Fre-Flo-plots. Magnawet-treated plots exhibited the lowest SAR values. In November, the lowest SAR values were recorded on Zeta-Core plots (Table 4).

Our results indicate that water conditioners did not consistently improve or remediate soil salinity. A clear trend showing similar results for all the parameters measured over a longer time period could not be established. Additionally, on sampling dates where conditioners appeared to improve soil salinity (for example, October 2005, September 2006), all soil data were still well below threshold levels considered critical for cool-season turfgrass growth. After four years of research investigating several non-chemical water conditioners, we could not substantiate a consistent positive impact of these conditioning units on turf quality and root-zone salinity.

Funding

Financial support of the study was provided by New Mexico State University’s Agricultural Experiment Station and Office for Facilities and Services; Cooperative State Research, Education and Extension Service, U.S. Department of Agriculture under Agreement No. 2005-34461-15661 and 2005-45049-03209; United States Golf Association; Rio Grande GCSA; Southwest Turfgrass Association; and the Environmental Institute for Golf. The authors are also grateful for the donations from Helena Chemical Co., Pennington Seed Inc. and Zeta-Core USA.

Acknowledgments

The authors are grateful for the help and support of 27-year GCSAA member Bruce Erhard, golf course superintendent at NMSU’s golf course. Dr. Rossana Sallenave’s help with the manuscript is also greatly appreciated. A longer version of this paper was published on Sept. 24, 2012, in the online journal Applied Turfgrass Science (www.plantmanagementnetwork.org/ats/) as “Usefulness of non-chemical water conditioners for managing turfgrasses and their root zones” by B. Leinauer, T. Barrick, M. Serena, M. Schiavon, B. Meier and C. Robertson.

Literature cited

1. Duncan, R.R., R.N. Carrow and M.T. Huck. 2009. Turfgrass and Landscape Irrigation Water Quality: Assessment and Management. CRC Press, Taylor and Francis Group, Boca Raton, Fla.

2. Johnson, C.M. 2007. Establishing cool- and warm-season turfgrasses using saline irrigation in combination with subsurface drip irrigation. M.S. thesis. New Mexico State University, Las Cruces, N.M.

3. Karcher, D.E., and M.D. Richardson. 2005. Batch analysis of digital images to evaluate turfgrass characteristics. Crop Science 45:1536-1539.

4. Krans, J.V., and K. Morris, 2007. Determining a profile of protocols and standards used in the visual field assessment of turfgrasses: A survey of national turfgrass evaluation program-sponsored university scientists. Online. Applied Turfgrass Science doi:10.1094/ATS-2007-1130-01-TT.

5. Leinauer, B., T. Barrick, M. Serena, M. Schiavon, B. Meier and C. Robertson. 2012. Usefulness of non-chemical water conditioners for managing turfgrasses and their rootzones. Online. Applied Turfgrass Science doi:10.1094/ATS-2012-0924-01-RS.

6. Richardson, M.D., D.E. Karcher and L.C. Purcell, 2001. Quantifying turfgrass cover using digital image analysis. Crop Science 41:1884–1888.

7. United States Salinity Laboratory staff. 1954. Diagnosis and improvement of saline and alkali soils. USDA Handbook 60. U.S. Government Printing Office, Washington, D.C.

8. Xiong, X., G.E. Bell, J.B. Solie, M.W. Smith and B. Martin. 2007. Bermudagrass seasonal responses to nitrogen fertilization and irrigation detected using optical sensing. Crop Science 47:1603-1610.

Bernd Leinauer (leinauer@nmsu.edu) is a professor and turfgrass Extension specialist, Bernd Maier is the Extension viticulturist, and Ty Barrick is a research associate, all in the department of Extension plant sciences; and Matteo Serena and Marco Schiavon are graduate research assistants in the department of plant and environmental sciences at New Mexico State University, Las Cruces, N.M.