Evaluation of Atmometers within Urban Home Lawn Microclimates

Abstract

2359ReseaRch T urfgrasses in the United States are estimated to cover 16 to 20 million hectares, an area three times larger than any irrigated crop (Morris, 2003;Milesi et al., 2005). The total turfgrass area in the United States is likely to increase greatly as urbanization continues to expand (Alig et al., 2004). Irrigation of turfgrasses in urban areas is a common practice, creating an increasing demand for water in expanding urban areas. However, many homeowners do not understand how to manage the irrigation for their lawn (Bremer et al., 2012(Bremer et al., , 2013(Bremer et al., , 2015. A better understanding of turfgrass irrigation requirements (i.e., ET) would help homeowners manage irrigation more efficiently, reducing the demand for water.Turfgrass irrigation requirements are often determined by ET estimates. Typically ET estimates are obtained from either on-site or off-site weather stations that collect weather data to calculate ET using an empirical model. However, a weather station can be expensive to set up and maintain. Siting of the weather station can also create a bias resulting in inaccurate ET estimation (Ley et al., 1996). This is problematic for practitioners who utilize ET-based irrigation scheduling.ABSTRACT An atmometer is an inexpensive tool used to measure evapotranspiration (ET) in situ. The effects of microclimates associated with urban lawns on the performance of atmometers are not well documented. our objective was to compare ET estimates between atmometers and the FAo-56 penman-Monteith equation (pM ET , FAo56-pM), including within urban lawns. The study was conducted in six lawns in 2010 and one in 2011 in Manhattan, KS, and four lawns in Wichita, KS, in 2011. A weather station and atmometer were positioned in an open sward of turfgrass near each city during each measurement period in Manhattan and Wichita. A commercially available Bellani plate atmometer, using a green canvas cover for grass reference ET (AT ET ), was placed next to a portable weather station in two contrasting microclimates within each lawn. Weather stations recorded temperature, net radiation, relative humidity, and wind speed data used to calculate pM ET . open sward AT ET (4.73 mm d -1 ) averaged 14% less than pM ET (5.48 mm d -1 ). Within microclimates, AT ET (3.94mm d -1 ) averaged 22% greater than pM ET (3.23 mm d -1 ). The differences in ET estimates between measurement techniques varied with wind speed, net radiation, and vapor pressure deficit. The best relationships between AT ET and pM ET , at the open sward and within microclimates, occurred when wind speed was >1 m s -1 , vapor pressure deficit was >2 kpa, and net radiation was >5 MJ m -2 d -1 . overall, atmometers can provide reliable estimates of pM ET and could benefit practitioners with irrigation management within microclimates. Dep. of Horticulture, Forestry and Recreation Resources, Kansas State Univ., 2021 Throckmorton Plant Sciences Center, Manhattan, KS 66506. Contribution no. 15-152-J from the Kansas Agric. Exp. Station.

Comparison of Leaf Area Index, Surface Temperature, and Actual Evapotranspiration Estimated Using the METRIC Model and In Situ Measurements

“…The wind speed at time of satellite overpass was high (5.9 m s −1 ) (black line in Figure 15). Similar results were found by Chen and Robinson, Gleason et al, and Peterson et al [64,65,66]. They observed that as the wind speed increased, ETr from atmometer and ETr from the Penman–Monteith (P–M) equation diverted.…”

Quality‐Based Field Research Indicates Fertilization Reduces Irrigation Requirements of Four Turfgrass Species

“…Potential ET was estimated with an atmometer (ETgage, Model A, ETgage Company) adjacent to the experimental area, and the length of irrigation time was calculated using the irrigation system precipitation rate. Peterson et al (2015) determined that ETgage estimates were strongly correlated (r 2 = 88%) with ET estimates calculated by the Penman Monteith (FAO-56-PM) empirical model when located in an open sward, similar to this experiment. In addition, Hanks et al (1976) recommends that each irrigation event be collected on intervals against the gradient to account for any wind distortion or other influences on irrigation delivery.…”

Comparative Analysis of METRIC Model and Atmometer Methods for Estimating Actual Evapotranspiration

“…Research demonstrated that ET r estimated with atmometers was moderately correlated ( 2 = ±0.70) with weighing lysimeters values [35,36], strongly correlated ( 2 = 0.90) with pan evaporation values [37,38], and strongly correlated ( 2 = 0.92) with agrometeorological data values, for example, [39][40][41][42][43].…”