The Influence of Nutrients on Turfgrass Response to Treated Wastewater Application, Under Several Saline Conditions and Irrigation Regimes

The vast development of golf courses implemented in arid and semiarid regions, and the intense aquifer pumping rate of the water needed to irrigate these grass lands, provokes saline problems, mainly in the coastal areas, due to sea water intrusion. The reuse of treated wastewater to irrigate golf courses is considered as an alternative to the use of potable and ground water. The objective of this work was to study the response of Bermuda grass ( Cynodon dactylon , L. Pers) to several irrigation rates I with reused treated municipal wastewater in two locations in southern Portugal. Three different irrigation regimes based on different values of electrical conductivity (EC w ), namely EC w = 0.3 dS m −1 (potable water; control treatment), EC w = 1.6 dS m −1 , and EC w = 2.4 dS m −1 , using the sprinkler point source as experimental design, were established. Grass yield (aboveground biomass) was recorded monthly, and linear regressions between yield and net irrigation rates I were obtained. The results showed a clear and pronounced influence of the nutrient concentration in wastewater on the response of the turfgrass irrigated under several water regimes and saline conditions. Higher irrigation rates (I > 6 mm d −1 ) triggered higher yields, but this increase was slightly lower under higher salinity conditions (EC w = 2.4 dS m −1 ). We conclude that wastewater can be used to irrigate turfgrass as an alternative to potable water due to the presence of significant quantities of some essential nutrients, like K. However, the EC of wastewater can be a limiting factor.