Open AccessMeasurement of Unirrigated Turfgrass Evapotranspiration Rate in the Red River Valley
Author(s) -
Niaghi Ali Rashid,
Jia Xinhua,
Scherer Thomas,
Steele Dean
Publication year - 2019
Publication title -
vadose zone journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.036
H-Index - 81
ISSN - 1539-1663
DOI - 10.2136/vzj2018.11.0202
Subject(s) - evapotranspiration , environmental science , hydrology (agriculture) , irrigation scheduling , water content , irrigation , crop coefficient , eddy covariance , canopy , growing season , soil water , moisture , agronomy , soil science , geography , ecosystem , meteorology , ecology , geology , geotechnical engineering , archaeology , biology
Core Ideas Soil moisture is needed in defining well‐watered turfgrass condition in evapotranspiration measurement. Deep soil moisture supports turfgrass growth when surface soil moisture is not sufficient. The ET a can be estimated from 0.96 ET o using the ASCE‐EWRI standardized method for well‐watered turfgrass. The ASCE‐EWRI standardized reference ET equation can be used for water management of turfgrass in northern cool climates and during drought periods. Turfgrass actual evapotranspiration (ET a ) measurements are critical for water management and irrigation scheduling. With no historical ET a measurements in eastern North Dakota, turfgrass ET a rates were measured with the residual method using eddy covariance instrumentation and two arrays of soil moisture sensors on unirrigated turfgrass under natural conditions in the 2011, 2012, and 2013 growing seasons. An on‐site weather station provided weather data to calculate the standardized grass‐based reference evapotranspiration (ET o ) (Allen et al., 2005). The daily ET a /ET o ratios were screened using the criteria of soil moisture ≥50% of available water for the top 30 cm of the root zone, rain amounts ≤10 mm, and a recovering period after drought. The screened monthly average ET a /ET o ratios for the unirrigated turfgrass were 1.03, 0.98, 0.94, 0.90, 0.82, and 1.18 from May to October. The mean ET a /ET o ratio for the entire growing seasons was 0.96, implying that the American Society of Civil Engineering–Environmental and Water Resource Institute ET o method was valid for guiding the turfgrass ET a calculation even in unirrigated and cold climate conditions. Because this is the first reported study on ET a measurement of a turfgrass site, the limited data can provide a baseline on water management for turfgrass under various weather conditions in this region. The results indicated that a monthly refinement of ET a /ET o values might be required to maintain the landscape turfgrass quality more precisely in terms of water management.