Soil moisture variability on golf course fairways across the United States: An opportunity for water conservation with precision irrigation

Authors: STRAW, CHASE - Texas A&M University; BOLTON, CONNOR - Texas A&M University; YOUNG, JOEY - Texas Tech University; Hejl, Reagan; FRIELL, JOSH - Toro Company; WATKINS, ERIC - University Of Minnesota

Submitted to: Agrosystems, Geosciences & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/19/2022
Publication Date: 12/7/2022
Citation: Straw, C., Bolton, C., Young, J., Hejl, R.W., Friell, J., Watkins, E. 2022. Soil moisture variability on golf course fairways across the United States: An opportunity for water conservation with precision irrigation. Agrosystems, Geosciences & Environment. 5(4). Article e20323. https://doi.org/10.1002/agg2.20323.
DOI: https://doi.org/10.1002/agg2.20323

Interpretive Summary: Fairways are intensely managed areas present on all golf courses and represent a large proportion of the irrigated area within a course. The commonly relied upon approach to schedule irrigation on fairways has been a combination of visual observations of the turfgrass and short-term forecasts. This approach often leads to all fairway areas across the course receiving the same amount of irrigation, regardless of specific area needs. Precision irrigation is a strategy which attempts to reduce water consumption by only applying irrigation where, when, and in the amount needed. A useful component of precision irrigation is to generate soil moisture variability maps, which can be developed by using soil moisture sensors equipped with Global navigation Satellite System (GNSS) technology. Previous research has noted excessive variability within golf course fairways, however this research has been limited to only a few states and a few fairways per course. To encourage repeatable, uniform, and large-scale data collections, a protocol was developed at the University of Minnesota in 2019 which outlines standard procedures to collect georeferenced soil moisture data using a GNSS-equipped, handheld soil moisture meter. The objective of this case study was to report fairway soil moisture variability findings from nine golf courses (four public and five private) in eight states (AZ, CA, CO, FL, KS, MN, NH, and TX) that completed the protocol during 2019-2022. Approximately 80-315 georeferenced soil moisture data points were collected per fairway using either a FieldScout TDR 300 with an external GNSS receiver or FieldScout TDR 350 with an internal GNSS receiver. For each course, data was collected on the same day and 7 to 14 fairways were considered. Soil moisture variability was present regardless of climate region and course characteristics, indicating soil moisture variability may be inevitable at large scales. These findings suggest that advancing irrigation practices and technologies to conserve water resources through precision irrigation is needed.

Technical Abstract: Conventional golf course fairway irrigation relies on visual observation of the turfgrass, followed by secondary considerations of short-term weather forecasts, which oftentimes lead to ‘blanket’ applications to an entire area. Precision irrigation may achieve water use reductions by irrigating only where, when, and in the amount needed. Technology can further enhance its application; for example, using global navigation satellite system (GNSS)-equipped soil moisture sensors for creating fairway soil moisture maps to identify variability. However, research regarding soil moisture variability on fairways at golf courses that differ by climatic region and course characteristics is limited. The objective of this case study was to report fairway soil moisture variability findings from nine golf courses in eight states in the United States that completed a soil moisture mapping protocol during 2019–2022. Each course used a handheld GNSS-equipped soil moisture device to collect georeferenced soil moisture (percentage volumetric water content [VWC]) data from seven to 14 of their fairways. Soil moisture variability was assessed through summary statistics, box and whisker plots, and spatial maps. The mean soil moisture on fairways across courses was 22.4–48.8% VWC, the range was 27.6–43.7% VWC, and the CV was 7.5–39.4%. Box and whisker plots and spatial maps of soil moisture aided in visualizing variability within and between fairways at all courses. Results suggest that golf course fairway soil moisture variability is inevitable regardless of climatic region and course characteristics, which further reiterates the need for advanced irrigation practices and technologies for water conservation via precision irrigation.