Winter 1999

Articles:

The Benefits of the Toro® HydroJect® 3000 for Golf Course Superintendents

Soil water infiltration and leaching of salts improve significantly when the summer cultivation program on putting greens includes using a Toro HydroJect 3000 in the raised position.

By Laosheng Wu

Asst. CE Irrigation/Water Management Specialist

Using a Toro HydroJect in the raised position significantly increased field infiltration rates and decreased the soil's salinity during summer cultivation treatments on an annual bluegrass/ creeping bentgrass putting green, based on the results of a two-year study we recently completed on an in-use practice putting green at Industry Hills Golf Courses in Industry, California.

Golf course superintendents must employ the best management and cultural practices to reduce annual bluegrass/ creeping bentgrass decline in the summer, which otherwise impairs the visual appeal and quality of putting greens in Southern California. Maintaining good soil physical characteristics is absolutely essential for successful putting green management in the summer. At that time of year, the detrimental effects of high traffic and prolonged high temperatures are compounded in soils that have compromised physical characteristics--limited gas exchange, limited soil water infiltration and percolation, and high concentrations of salts--which act together to increase plant stress and summer decline.

In the raised position, the Toro HydroJect significantly improved field infiltration rates during four of five test dates and decreased the soil's electrical conductivity (ECe in the l- to 3-inch and 3- to 6-inch root zone depth, based on the results of our two-year study. The magnitude of the decrease in soil ECe, is biologically important for management of annual bluegrass putting greens during the summer season, said Dr. Robert Green, UCR Turfgrass Research Agronomist, who collaborated with me on the project as co-investigator.

Using the HydroJect equipment in the raised position during the summer can help golf course superintendents in the region to reduce the combined stresses due to high soil and air temperatures, high foot traffic, and soil salinity by improving soil water infiltration and the leaching of salts.

Kit Available Now

"A kit is available now to run the HydroJect 3000 in the raised position," said Dana Lonn, Director of Advanced Turf Technology at the Toro Company in Minneapolis, MN. It is just as safe to use the equipment in the raised or lowered position, he said. The kit can be ordered from any of Toro's distributors by calling (800) 803-8676, he said.

"My colleagues are excited about using the HydroJect in the raised configuration because I have told them that it works; based on my personal experience and UCR's research results at our facility," said Bert Spivey, Certified Golf Course Superintendent (CGCS) at Industry Hills Golf Courses and President of the GCSA of Southern California

"We like to think of ourselves as 'UCR-West'," Spivey said recently, "because we benefit from opening our golf courses to university research." Spivey cooperated with Green and me on the day-to-day operations of the two-year research project, which was conducted on one of the in-use practice greens Spivey manages, the Dwight D. Eisenhower practice green, which is 80% annual bluegrass and 20% creeping bentgrass. It is irrigated with effluent water and was constructed to USGA specifications in 1978. The golf courses are located in a mild, midland climate area of the region.

Putting UCR Results in National Perspective

"The results from the University of California, Riverside research add to the national database regarding the efficacy of our equipment," Lonn said. Previous research by Dr. Paul Rieke at Michigan State and Dr. Jim Murray at Rutgers showed that the Toro HydroJect 3000 increases water infiltration and provides an environment for better rooting. But you can't learn everything about a products usefulness in one geographical location. Dr. Bob Carrow at the University of Georgia showed that the HydroJect in the raised position, used in conjunction with other management practices, such as topdressing, can decrease summer decline of bentgrass greens in the Southeast by managing the surface organic layer," he said.

"In California and other areas of the Southwest, the soil must be leached periodically, due to high concentrations of dissolved salts in the water. We were interested in finding out if the HydroJect could facilitate the leaching process. The results from the UCR research are solid evidence that the HydroJect 3000 significantly facilitates the leaching process in the raised position. Golfers appreciate our product because soils that receive a HydroJect treatment heal more quickly than those subjected to conventional aeration techniques," Lonn said.

The Toro HydroJect 3000 uses short bursts of high velocity streams of water to cultivate the soil while minimizing surface disruption (Fig. 1). The equipment enables turf managers to use less plant stressful techniques to cultivate the soil, which is particularly helpful during the summer when annual bluegrass/ creeping bentgrass is growing under stressful environmental conditions in Southern California.

In the two-year UCR study, the HydroJect equipment did not have a significant effect on the soil's air-filled porosity, and bulk density for a 19-week period at the 0.4 to 2.4-inch soil depth zone at 8 to 9 days following cultivation treatments, which was not unexpected, since creating channels does not alter soil texture. Results for the oxygen diffusion rate at the 1-inch soil depth 8 to 11 days following cultivation treatments were also insignificant using the HydroJect in the raised and lowered positions. The effects of the HydroJect on root mass density were also insignificant.

Cooperating with Green and me were UCR staff research associates Grant Klein and Ralph Strohman. For a copy of the final HydroJject research report, please contact me at laowu@mail.ucr.edu or by telephone (951) 827-4664).

What Does EC Mean?

Electrical conductivity (EC) is a measure of the soil salinity or the total dissolved salts in the soil solution (640 ppm = I decisiemens (dS)/m). The EC of irrigation water in Southern California (ECi,) ranges from 0.3 to 1.5 dS/m. If the ECi, on a golf course is 1.0 dS, which is equal to 640 ppm or 640 mg/L, and the green is irrigated with 3.2 ft/yr, then a 5,000 sq ft golf course green would receive about 640 lb of salts yearly.

Salt inputs are not divided equally throughout the year. Most of the salts are delivered from April through October - about 85 lb/mo/5,000 sq ft green in the example above. Effective irrigation management prevents salts from accumulating to concentrations that damage the turf, particularly in the spring and summer months.

One standard method for measuring EC is to make a saturated paste, take an extract from it, and run the EC of the extract (EQ, as was done in this study. Another standard technique is to take the ECiw.

Typically, golf course superintendents in Southern California use an EC meter and check the readings from the meter against a calibration curve to get the EC, value.

Summer Management Principles

Summer cultivations are not a substitute for spring, and/or fall hollow-tine coring, followed with topdressing, Green said. Summer cultivation treatments are probably effective in reducing soil salinity due to surface/upper root-zone phenomena that limit water infiltration and percolation through the root zone, he said.

Light topdressing (0.5 ft3/1000 ft2) has been shown to decrease surface soil organic matter (0 to 1.2 inches) and may be practiced from early to mid-summer. A knowledgeable fungicide program should be practiced at this time. Spoon-feeding fertilizers during the summer is highly recommended, Green said. Foliar applications of iron seem to improve annual bluegrass/creeping bentgrass.

If there is the possibility of root dieback, applications of cytokinins (seaweed extracts) may improve survival and recovery of annual bluegrass/creeping bentgrass. Hand-watering is effective when root dieback occurs, and wetting agents are efficacious when hydrophobic soil surfaces and layers impede water uptake.

A higher height of cutting and a lower mowing frequency will improve annual bluegrass/creeping bentgrass putting greens in the summer.

"The most successful way to cool grass is to move air across the canopy," Green said. If low air movement is a problem, thinning vegetation surrounding the green is the management alternative of choice. Using fans for cooling purposes is another option.

Summer traffic is an economic benefit but a stress on the grass. If possible, practice some form of traffic control, Green said.

Reclaimed Water Usage in California

The California Water Code mandates municipal wastewater reclamation and reuse, also known by the term, 'water recycling' in California. The Code states that no person or public agency shall use water, suitable for potable, domestic use for nonpotable uses, including, but not limited to, golf courses cemeteries, highway landscaped areas, and industrial uses, if reclaimed water is available at reasonable cost and meets all of the conditions and quality standards set forth in the Code. The Office of Water Recycling at the California State Water Resources Control Board (SWRCB) continuously updates its database of reclaimed water usage statewide. Approximately 354,000 acre-feet (af) of water is reclaimed per year. Usage by sector is given in Table 1. Large water reclamation projects (>1,500 af/yr) use about 80% of the reclaimed water, said Lynn Johnson, Chief, Office of Water Recycling, SWRCB. Both the total amount of wastewater discharged and the amount of wastewater being reclaimed continue to increase. Recent estimates of the percentage of wastewater recycled statewide range from 8 to 12%.

Table 1. Reclaimed Water Usage in California by Sector
Category of Use % af/yr
(thousands)		 Specific Types of Use
Agricultural irrigation 48.3 171 Food crops, sod farms, nurseries, fodder crops, fiber crops, seed crops, silviculture
Landscape Irrigation 16.1 57 Golf courses, parks, playgrounds, school grounds, cemeteries, greenbelts, roadway rights-of-way
Groundwater Recharge 12.7 45 Aquifer recharge, salt water intrusion control, ground subsidence control
Wildlife habitat 6.5 22 Wildlife habitat, miscellaneous enhancements
Recreational Impoundments 6.2 22 Boating, fishing, duck hunting
Industrial use 5.1 18 Cooling, boiler feed, stack scrubbing, process water
Other 5.1 18 Other /mixed applications
Source: Lynn Johnson, Chief, Office of Water Recycling, California SWRCB (personal communication), 2/99. Updates of these data, which were updated in 1/99, are intended to be put on the SWRCB website later this year.

Water Recycling Criteria in California

California was the first state to adopt water reclamation and reuse standards to protect public health. The first reclaimed water application to be regulated was the use of wastewater for agricultural irrigation. Today, California and Florida have the most comprehensive reuse criteria based on the water's end use.

California's Water Recycling Criteria, currently being revised, were adopted in 1978 as wastewater Reclamation criteria by the Department of Health, Services (DHS), which has authority and responsibility, under California law to establish health related standards for water reclamation and reuse. The Water Code provides for 9 California Regional Water Quality Control Boards, (RWQCB). Local health agencies have independent authority and may impose requirements more stringent than those specified by the California DHS or RWQCB.

Total coliform bacteria levels are used as disinfection performance standards in California. The total coliform limits and the treatment required depend on the type of nonpotable end use of the reclaimed water (Table 2). The complete Recycling Criteria are available at http://www.dhs.ca.gov/ps/ddwem/publications/lawbook.htm.

Table 2. California Treatment and Quality Criteria for Nonpotable Uses of Reclaimed Water
Types of Use Total Coliform Limitsa Treatment Required
Irrigation of orchardsb, vineyardsb, fodder, fiber, seed crops; food crops that undergo commercial pathogen-destroying processing; flushing sanitary sewers No Limit Established Secondary
Irrigation of landscape areasc, sod farms/ornamental nursery stock; pasture for milking animals; cleaning roads; commerical cooling water (no mist created); nonstructural fire fighting 23/100 mL Secondary + disinfection
Surface irrigation of food crops; restricted landscape impoundments 2.2/10 mL Secondary + disinfection
Irrigation of food cropsd and open access landscape arease; toilet and urinal flushing; industrial process water; snow making; structural fire fighting; industrial cooling (mist created) 2.2/100 mL Secondary + disinfection, coagulationf, infiltrationg

aBased on running 7-day median. bNo contact between reclaimed water and edible portion of crop. crestricted-access golf courses, cemeteries, freeway landscaping, and other controlled-access landscape areas. dContact between reclaimed water and edible portion of crop, includes edible root crops. eUnrestricted-access golf courses, parks playgrounds, schoolyards, residential landscaping, other uncontrolled-access landscaped areas. fNot required if the turbidity of the influent to the filters does not exceed 5 nephelometric turbidity units (NTU) more an 5% of the time. gTurbidity of filtered effluent cannot exceed a daily average of 2 NTU.

Table 2 is adapted and modified from Crook, J. 1998. Water Reclamation and Reuse Criteria. In: T. Asano (ed.), Wastewater Reclamation and Reuse (Volume 10 of the Water Quality Management Library), Technomic Publishing Co., Inc., Lancaster, PA. Additional sources for Table 2: Bob Hultquist, P.E., Chief, Technical Operations Section, Drinking Water Program, California DHS (personal communication), 2/99; Draft Water Recycling Criteria, California DHS, 9/98.

Microbial Considerations in Wastewater Reclamation and Reuse

Part II. Survival and Fate of microbial Pathogens on Reclaimed Wastewater-Irrigated Crop

(Editor's Note. Part I. Types and Occurrence of Microbial Pathogens in Wastewater appeared in the Fall 1998 issue of Soil Water and Irrigation Management. Part III. Assessing Microbial Risks will appear in the Spring 1999 issue. Part II is adapted from and excerpted in part from "Microbial Considerations in Wastewater Reclamation and Reuse," by Dr. Marylynn V. Yates, Professor of Environmental Microbiology and Extension GroundWater Quality Specialist in the Department of Environmental Sciences at the University of California, Riverside and Dr. Charles P. Gerba, University of Arizona, Tucson. The chapter is published in Wastewater Reclamation and Reuse (1998), edited by Takashi Asano, Ph.D., RE (Volume 10 of the Water Quality Management Library), Technomic, Publishing Co., Inc, Lancaster, PA.). Extensive references are provided at the end of the chapter.

The three most important environmental factors affecting the survival of microbial pathogens on reclaimed wastewater-irrigated food and nonfood crops are temperature, moisture, and exposure to sunlight. The lower the temperature, the longer the survival of an enteric pathogen in any environment. As relative humidity, moisture content, and rainfall increase, microbe survival time increases. Desiccation causes rapid-inactivation of viruses and protozoan parasites. Ultraviolet light in sunlight inactivates microbes by inducing damage to their nucleic acids, although it is not effective for inactivation of many parasites, such as Cryptosporidium, due to the thick walls of the oocysts. Wastewater containing pathogens can contaminate crops directly via irrigation or indirectly via soil contact. Crops in the field can also be contaminated by blowing dust or by workers, birds, and insects that spread microbes from irrigation water or soil to the edible portion of the crop.

Food Crops: Potential Microbial-Mediated Illness

Transmission of foodborne illness by enteric pathogens due to irrigation with reclaimed water has been documented for more than a century, which explains why irrigation of food crops, especially those eaten raw, is usually forbidden. Crops eaten raw should only be irrigated with reclaimed water that meets the same quality standards as reclaimed water intended for potable reuse. Lower water quality standards have been applied to reclaimed water used for orchard crops, such as citrus and other fruits; however, recent outbreaks associated with apples, imported raspberries and lettuce, caused by Cryptosporidium, Cyclospora, and hepatitis A-virus, respectively, suggest that reclaimed water of a high microbial quality should be used for these crops as well. If the crop is used for animal feed or grazing, there is a potential for the transmission of enteric pathogens, such as Salmonella, enteropathogenic E. coli, and Cryptosporidium, that infect both man and the animal.

Most foodborne illness associated with enteric microorganisms occurs during the mishandling of food, typically when an ill food handler does not practice proper sanitation (i.e., hand washing). Outbreaks of enteric viruses, including hepatitis A and E, rotavirus, Norwalk virus, echoviruses, and small round viruses have been linked to fresh produce contaminated during food handling.

Outbreaks caused by enteric bacterial, pathogens in developed countries have been associated in recent years with vegetables and fruits imported from developing countries or from areas where lower water quality is the suspected source. Like Salmonella and Shigella, E. coli can grow in cut fruits and vegetables. Cases have been reported on watermelon, cantaloupe, and tomatoes.

Isolation of Cryptosporidium, Giardia lamblia, and Entamoeba histolytica on market vegetables in Mexico City and Costa Rica is evidence that protozoan cysts and oocysts can survive long enough to get into the food supply.

Non-Food Crops: Urban Landscape Irrigation

Association of microbial-mediated illness from non-food crops irrigated with reclaimed water, such as golf courses, school playgrounds, parks, cemeteries, freeway medians, and residential lawns, is a potential health concern for persons employed in landscape irrigation, due to the risk of potential exposure to microbial pathogens via contact with plant surfaces wetted by reclaimed-water and via exposure to pathogens in aerosols that result from spray irrigation. The potential exposure risk extends to persons engaged in recreation on turf irrigated with reclaimed water, such as golfers and children, who may be in contact with plant surfaces irrigated with reclaimed water. Despite these potential risks, no cases of illness have been reported to date from such exposure.