Efficient Irrigation for Recreational Turfgrass in New England: Evapotranspiration and Crop Coefficients
Creators: name: Poro, James W
Publisher: name: University of Massachusetts Amherst
Year: 2015

description: <strong> ABSTRACT</strong>
<strong>EFFICIENT IRRIGATION FOR RECREATIONAL TURFGRASS IN NEW ENGLAND: EVAPOTRANSPIRATION AND CROP COEFFICIENTS</strong>
AUGUST 2014
JAMES PORO, B.S., UNIVERSITY OF MASSACHUSETTS AMHERST
M.S., UNIVERSITY OF MASSACHUSETTS AMHERST
Directed by: Dr. J. Scott Ebdon
As water demand increases it will become more imperative for golf course superintendents, landscape managers, and other industry professionals to improve water use efficiency in the management of recreational turfgrass. Scheduling irrigation according to actual turfgrass evapotranspiration rates (ET<sub>T</sub>) is an integral component of efficient irrigation practices. Impracticality of field derived ET<sub>T</sub> for industry use, however, directs the need of weather station derived reference (predicted) evapotranspiration (ET<sub>0</sub>). To accurately predict (estimate) ET<sub>T</sub> of turf and other crops, scientifically derived landscape (crop) coefficients (K<sub>c</sub> values) are used in conjunction with mathematical models that incorporate local meteorological data. Research is limited, however, in identifying K<sub>c</sub> values and subsequent ET<sub>0</sub> for turfgrass species selected and maintained under high intensity recreational practices congruent of golf courses and sports fields in the cool-humid northeast climate. Therefore, objectives of this study were to (i) observe and record ET<sub>T</sub> of three commonly selected recreational turfgrass species; 'Exacta' Perennial ryegrass (<em>Lollium perenne </em>L<em>.)</em>, 'Touchdown' Kentucky bluegrass (<em>Poa pratensis </em>L.), and 'Memorial' Creeping bentgrass (<em>Agrostis stolinifera </em>L.) maintained as golf and sports turf, (ii) analyze the impact various management practices (nitrogen fertility and height of cut) have on ET<sub>T</sub>, (iii) develop accurate K<sub>c</sub> values appropriate for use with the recommended FAO 56 Penman-Monteith mathematical model for accurate ET<sub>0</sub> of recreational turf maintained in the cool-humid northeast.
Four heights of cut (HOC) and two nitrogen fertility rates (N) were evaluated to determine their impact on turfgrass growth and subsequent water use and ET<sub>T</sub> of three recreational turfgrass species. Golf turf (creeping bentgrass) maintained at a lower height of cut than sports turf exhibited a smaller leaf area component and a significantly lower (20%) ET<sub>T</sub>. N applied as slow release (82%) throughout the growing season increased ET<sub>T</sub> by 5%, particularly with perennial ryegrass sports turf. Taller HOC also increased ET<sub>T</sub> by 10% due to increased leaf area indices and subsequent decreased resistance to ET. Predicted ET<sub>0</sub> according to FAO 56 for all three years of the study (79 observations) captured 71% of ET<sub>T</sub>. Yearly and monthly calculations suggest less variable (cloudy) weather yielded more accurate ET<sub>0</sub>. Crop coefficient (K<sub>c</sub>) values established in conjunction with FAO 56 ET<sub>0</sub> ranged from 0.90 to 1.00 for shorter golf course turf (creeping bentgrass), and 1.15 to 1.25 for taller sports turf (Kentucky bluegrass and perennial ryegrass). Results indicate shorter grass exhibits a lower ET<sub>T</sub> than taller grass due to various factors, and in the case of industry application, FAO 56 ET<sub>0</sub> can accurately estimate ET<sub>T</sub> of recreational turf in the cool-humid northeast when fitted with appropriate K<sub>c</sub> values.