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Title: Varying evapotranspiration and salinity level of irrigation water influence soil quality and performance of perennial ryegrass (lolium perenne l.)

Author
item SCHIAVON, MARCO - University Of California
item MEIHLS, ALEA - University Of California
item LEINAUER, BERND - New Mexico State University
item Suarez, Donald
item BIARD, JIM - University Of California

Submitted to: Urban Forestry and Urban Greening
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/9/2017
Publication Date: 1/21/2017
Citation: Schiavon, M., Meihls, A., Leinauer, B., Suarez, D.L., Biard, J. 2017. Varying evapotranspiration and salinity level of irrigation water influence soil quality and performance of perennial ryegrass (lolium perenne l.). Urban Forestry and Urban Greening. 26:184-190. http://dx.doi.org/10.1016/j.ufug.2017.01.006.
DOI: https://doi.org/10.1016/j.ufug.2017.01.006

Interpretive Summary: Scarcity of fresh water in the southwestern U.S. as well as other arid regions has led to increasing use of recycled waste water and brackish waters for landscape irrigation. Under conditions of low to moderate salt stress most plants decrease biomass production but do not show other overt symptoms of salt stress. As landscape vegetation is generally assessed by appearance not production, it seems desirable to consider use of brackish waters for these environments, saving fresh water for household use and crop production. A study was conducted to evaluate the response of perennial ryegrass (Lolium perenne L.) ‘SR 4550’ turf to varying quality and quantity of irrigation water. A modified line-source sprinkler irrigation system provided a salinity gradient (electrical conductivity (ECw) of 0.6 to 4.2 dS m-1 in between lines. Irrigation was scheduled in four separate irrigation zones perpendicular to the irrigation lines according to 80, 100, 120, and 140% of reference evapotranspiration.. Changes in turf quality were related to the number of days that the area was irrigated with saline water. Both time and water quality accounted for 54% and 46% of the variability in quality and cover, respectively at 80% of reference ET. A model was created to quantify decline in turf quality in relationship to % reference ET irrigation and salinity accumulation in the rootzone. Our results suggest that perennial ryegrass requires irrigation scheduling at 140% reference ET, when irrigation water is below ECw ~ 1.7 dS m-1, and EC of soil extracts below 3.8 dS m-1 to maintain acceptable quality in Riverside, CA. These findings are of interest to extension specialists and turfgrass and landscape managers in the southwestern U.S. and other semi-arid and arid regions with warm climates.

Technical Abstract: Increasing use of recycled water that is often high in salinity warrants further examination of irrigation practices for turfgrass health and salinity management. A study was conducted during 2011-2012 in Riverside, CA to evaluate the response of perennial ryegrass (Lolium perenne L.) ‘SR 4550’ turf to varying quality and quantity of irrigation water. A modified line-source sprinkler irrigation system provided a salinity gradient (ECw ~ 0.6 to 4.2 dS m-1) in between lines. Irrigation was scheduled in four separate irrigation zones perpendicular to the irrigation lines according to 80, 100, 120, and 140% ETo. Changes in turf quality (R2 = 0.30***), were primarily driven by the number of days that the area had been irrigated with saline water. When data were separated by irrigation amount, both time and water quality accounted for 54% and 46% of the variability (P < 0.001) in quality and cover, respectively at 80% ETo. A model was created to quantify decline in turf quality in relationship to %ETo replacement and salinity accumulation in the rootzone (R2 = 0.57). Our results suggest that perennial ryegrass requires irrigation scheduling at 140% ETo, irrigation water quality below ECw ~ 1.7 dS m-1, and ECe below 3.8 dS m-1 to maintain acceptable quality for 442 d in Riverside, CA.