Studies look at how varieties react to high-saline water

Photos courtesy of Bernd Leinauer, NMSU.

World conditions for growing turfgrass are continually changing with water becoming scarcer, and water quality issues are gaining increased significance. Learning the conditions under which grasses can perform is an essential step to developing appropriate turfgrass varieties to eventually be released. Trials must be conducted where the turfgrasses are exposed to heat, cold and drought.

With the increased use of recycled, or effluent, water in various locations across the U.S., screening turfgrasses for performance with high-salinity water is a major need. The New Mexico State University (NMSU) turfgrass screening facility provides a testing site with wide-ranging conditions that include extremes of hot and cold weather, drought and high-saline irrigation water. NMSU began a program of turfgrass screening several years ago and, more recently, has expanded its abilities to screen turfgrass under various conditions. Dr. Bernd Leinauer, NMSU turfgrass researcher, is leading a program with research results reaching far beyond the borders of the Chihuahuan Desert.

Marco Schiavon, Bernd Leinauer, Matteo Serena and Elena Sevostianova are working on a number of salinity studies at the NMSU salinity screening facility.

Screening site conditions

The Chihuahuan Desert region is almost 800 miles long and 250 miles wide, reaching from the southwestern states deep into Mexico. It includes the Rio Grande Valley of southern New Mexico and the San Simon Valley of southeastern Arizona. Las Cruces, N.M., home to NMSU, lies within the region at 4,000 feet elevation, where nighttime temperatures drop below freezing approximately 100 days of the year, and summer temperatures often reach 105 degrees. The low humidity and seasonal changes have made Las Cruces one of the fastest growing cities in the U.S. The location is also one of the best sites to screen turfgrass plants for performance under various growing conditions.

In addition to the range of climatic conditions, New Mexico has an extensive supply of high-saline water. Leinauer said, “Because of our geological setting, about 80 percent of New Mexico’s groundwater has high salinity. We have data from California, and from Phoenix, Ariz., and our water matches well with the salinity of the recycled water used in those locations.”

NMSU’s screening facility is located on a fully irrigated, 3-acre site at the southeast corner of NMSU’s campus, just south of the Aggie Memorial football field. About 2.5 acres are devoted to salinity screening. After initiating salinity studies a few years ago, NMSU ran out of space at its first site to conduct the requested screening.

“We were contacted by a number of companies about screening. We wanted to do it on a larger scale, but we were limited by the amount of land and water. We asked for more land,” Leinauer said. After receiving a positive response, setting up the new turfgrass screening site was a major cooperative effort, with the NMSU facilities department donating time and money to the project.

Leinauer said, “The well we drilled at our first site was geothermal. The water came out at 160 degrees. The water was used to heat the swimming pool and dormitories on our campus for some time. We drilled a new well at the new site. We have a low-lying aquifer with high-saline water, but it is not geothermal.”

Water is pumped into an 8-inch line that carries it to a holding tank and 2-inch PVC pipes take the water to the plots. A Toro DL 2000 drip irrigation system is then used to water the plots.

Leinauer has done extensive research on subsurface irrigation, and a number of sites in the Southwest are using subsurface irrigation. Leinauer’s earlier studies indicated that subsurface irrigation is an important component in water conservation since less water is lost to drift. Leinauer noted that some companies specify sprinkler irrigation for screening their grasses, providing settings comparable to the type of settings where the turfgrasses will be grown. MP rotator sprinkler heads provide uniform irrigation. Sprinkler and surface drip irrigation are used at the screening site.

NTEP trial plots are planted with bermudagrass in the foreground, tall fescue in the middle, and Kentucky bluegrass in the back.

Screening grasses

The NMSU screening facility is an NTEP testing site, and a number of seed companies have their varieties screened at the site. Warm-season grasses in screening studies include bermudagrass, seashore paspalum and zoysiagrass. Cool-season grasses include Kentucky bluegrass, ryegrass and tall fescue.

Barenbrug USA, Inc., Tangent, Ore., is looking for turfgrass varieties that can perform under drought conditions and in heat and cold, as well as with high-saline water. At the same time, turfgrasses that can perform well with lower inputs are being sought.

Dr. Joseph Wipff, turfgrass breeder at Barenbrug USA, noted that breeding for various characteristics is essential. Wipff said, “At the NMSU site, we not only test our current turfgrass varieties, developed at the breeding site in Oregon, but now also develop new varieties by screening germplasm.”

Wipff said, “The NMSU site has a saline level close to effluent water. It gives us an opportunity to see how the varieties perform under high salinity, and heat and cold stress. We’ll be ready to take them for testing to other test locations.”

Wipff noted the importance of looking at the salinity tolerance of various grasses. “We know that Kentucky bluegrass is very sensitive to salt,” he said. “Ryegrass is a cool-season turfgrass that has some salt tolerance, and there are differences in tolerance between varieties. We made selections and pushed it up a notch. Fescue is more salt tolerant than ryegrass.” He noted that the fescue has produced an improved turf quality and is good for the salinity levels found in recycled water.

Some grasses, such as alkali grass, have done well in high-salinity conditions in roadside settings. The next step is to screen turfgrasses to see how they perform through cold winters and with frequent mowing. The best performing varieties are then ready for trials in target areas for the development of turfgrass that can perform under both high-salinity and cold conditions with frequent mowing.

Expanding salinity studies

The Southwest is at the forefront for water shortages, and a number of restrictions have been placed on water consumption throughout the region. Recycled or low-quality groundwater is frequently used for landscape irrigation. Low-quality groundwater is water that does not meet standards for human consumption, such as New Mexico’s high-saline water.

A NMSU study is looking at advanc­ed turfgrass establishment issues when using high-saline irrigation water, and at associated establishment timing and fertility issues. Leinauer said, “Matteo Serena and Marco Schiavon, graduate students who received their under­grad­­­­­uate and master’s degrees at the University of Padova in Italy, have started new projects investigating establishment strategies when subsurface drip irrigation is used in combination with saline irrigation water. Matteo will look at establishment timing and fertilization to successfully grow warm-season grasses under saline drip irrigation, and Marco will determine minimum water requirements to establish warm-season grasses.”

An earlier NMSU study conducted by Leinauer and Casey Johnson, at that time a Master of Science student at NMSU, looked at the effects of saline irrigation water on turfgrass in comparison with potable water. That study found that while high-saline irrigation water reduced establishment of both warm and cool-season grasses, salt-tolerant turfgrasses such as alkali grass, seashore paspalum, bermudagrass and salt grass could be successfully established. The study also found that salinity tolerances were greater between cultivars within a single species than previously reported species differences, and that no significant differences occurred in establishment between subsurface drip and sprinkler irrigation.

With the wider use of recycled water, an increased need is expected for turfgrasses that will perform well with the high-saline levels found in the recycled water. Seed companies are likely to increase their work in developing new turfgrass varieties that will offer the needed qualities, and the climatic conditions and availability of high-saline water at the NMSU screening site will continue to offer expanded benefits in turfgrass performance screening.

Nancy Riggs is a freelance writer and frequent contributor to Turf. She resides in Mt. Zion, Ill.