Review of Turfgrass Evapotranspiration and Crop Coefficients

Abstract

Abstract. This review summarizes available data related to turfgrass evapotranspiration (ET c ) and crop coefficients (K c ) for both warm-season and cool-season grasses. Daily, monthly, or seasonal ET c rates and K c values determined at different locations in the U.S. are shown in this review, as well as the methods used to determine or estimate these values. Warm-season turfgrasses are characterized by their lower ET c rates compared to cool-season turfgrasses. Results showed that ET c is highly variable, not only between species but within same species. For example, ‘Tifway‘ bermudagrass, a warm-season turfgrass, showed ET c values of 1.78 mm d -1 in central Florida and 4.83 mm d -1 in Colorado, whereas zoysiagrass showed an ET c value of 9.40 mm d -1 in Texas. On the other hand, creeping bentgrass showed an ET c value of 3.3 mm d -1 for ‘Pennlinks‘ variety, while ‘Seaside‘ showed an ET c value of 10.7 mm d -1 , both in Nebraska. This variability was affected by genotype and plant morphological characteristics but was also due to weather conditions. Variability was also observed in turfgrass K c . Minimum and maximum monthly K c values for cool-season grasses were estimated as 0.05 and 1.05, respectively; for warm-season grasses, monthly K c values ranged from 0.28 to 0.99. The lowest reported K c values within a turfgrass species could serve as selection criteria to breed new varieties resistant to drought or contributing to water savings. Evapotranspiration rates and crop coefficients should be used with awareness of the local conditions under which the values were developed.