Irrigation scheduling based on Crop Water Stress Index (CWSI) for cool and warm-season turf grass under subsurface-drip irrigation method

Abstract

Aims: This study was conducted to determine irrigation scheduling basedon the Crop Water Stress Index (CWSI) of cool (CS) and warm-season (WS)turfgrass species under subsurface-drip irrigation method.Methods and Results: The field experiment was carried out during thesummer period of 2018 in the Agricultural Production and Research Centre(TURAM) of Silivri municipality, Istanbul-Turkey. Specific objectives wereto measure actual evapotranspiration (ETc) values for both turfgrass types,to compare their responses to different water levels, to determine CWSIvalues for both turfgrass species under different irrigation scheduling andopportunity of using CWSI in irrigation timing, to compare ETc withreference to evapotranspiration (ETo) calculated with five differentmethods and to determine crop coefficient curve (kc) for experimentalconditions, and to focus on the crop growing and irrigation managementparameters under subsurface-drip irrigation method. Three irrigationstrategies [I1:30%, I2:50%, and I3:70%) were tested in a split-plotrandomized complete block design with three replications. Thesestrategies corresponded, respectively, to 30%, 50% and 70% of totalavailable soil moisture depletion at 0-30 cm of the effective root zone andreturning soil moisture back to field capacity. The results indicated thatcolour, quality, fresh yield, dry matter yield, irrigation water use efficiency,water use efficiency, vegetation height and mowing were significantlydifferent in terms of irrigation strategies for both species. The mostappropriate irrigation strategies were I2:50% for CS and I3:70% for WSturfgrass which corresponded to a CWSI of 0.47 and 0.45, respectively.Conclusions: The amount of applied irrigation water in WS turfgrass was53% less than in CS turfgrass. Actual evapotranspiration was 26% lower forWS than for CS turfgrass.Significance and Impact of the Study: These results obtained from theexperiments will help choosing of turf type and irrigation scheduling tosave water in urban areas.