Effects of different amendments (organic matter and hydrogel) on the actual evapotranspiration and crop coefficient of turf grass under field conditions *

Abstract

The irrigation schedule in arid areas has to be efficient in order to reduce losses due to evaporation and deep infiltration. Irrigation optimization poses the need to establish with precision the value of actual evapotranspiration (ET a ), and the crop coefficient ( K c ). The water soil availability can be increased using hydrogel and organic matter amendments, and their effects could vary ET a and K c . The aim of this study was to determine the ET a , and K c of an experimental site with lysimeters on the Spanish Mediterranean coast cropped with a turf grass variety, Agrostis stolonifera ‐L‐93 , under field conditions, and amended with hydrogel and organic matter. Reference evapotranspiration (ET 0 ) was determined from meteorological data (FAO‐Penman‐Monteith equation). ET a was calculated from the water balance, and K c was obtained by dividing ET a by ET 0 . K c was calculated and compared on a yearly, monthly and daily basis. In summer, the differences between amendments become manifest:Unamended lysimeter (100% sand) had K c values (0.92‐1.16), similar to organic matter amended lysimeter (0.99‐1.17). Maximum and minimum K c values for the hydrogel amended lysimeters (1.04‐1.52) were higher than those from the other because of the ability of this compound to retain water, which facilitated evapotranspiration. Finally, hydrogel helped to maintain the turf grass quality.

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