Evapotranspiration estimates of soybean using surface renewal: Comparison with crop coefficient approach. (December 2022)

• Record Type: Journal Article
• Authors: Masanganise, J.; Kunz, R.; Clulow, A.D.; Mabhaudhi, T.; Savage, M.J.
• Is Part Of: Physics and chemistry of the earth. Volume 128(2022)
• Publication Date: 2022-12
• Subjects: Energy balance -- Latent heat flux -- Reference evapotranspiration -- Sensible heat flux; Geophysics -- Periodicals; Geochemistry -- Periodicals; Earth sciences -- Periodicals; Geodesy -- Periodicals; Astrophysics -- Periodicals; 550
• DOI: 10.1016/j.pce.2022.103244
• Languages: English
• ISSNs: 1474-7065

Abstract

Abstract: Evapotranspiration ( E T ) is widely considered the main consumptive water use in agricultural production and its accurate determination enables crop producers to make informed decisions. Field experiments were conducted in KwaZulu-Natal, South Africa to estimate soybean E T from sensible and latent heat flux obtained using the surface renewal (SR) method. Two versions of the SR method (SR2) were used. One version combines SR analysis with Monin-Obukhov similarity theory (MOST), hereinafter referred to as SRMOST. The other is a combination of SR analysis and dissipation theory (DT) referred to as SRDT. The E T estimated using SRMOST and SRDT ( E T S R M O S T and E T S R D T respectively) were compared to the E T obtained using the standard crop coefficient ( K c ) approach ( E T K c ). During flowering, pod formation and seed filling, both SRMOST and SRDT methods slightly overestimated E T obtained using K c approach with an average normalised root mean square error ( N R M S E ) of 23.4% and an average normalised mean absolute error ( N M A E ) of 10.1% for SRMOST and 21.7 and 9.4% for SRDT respectively. During senescence and at maturity, SRMOST and SRDT slightly underestimated E T compared to K c approach. The average statistical measures for SRMOST were N R M S E = 21.0% and N M A E = 9.2%. Correspondingly, the statistics for SRDT were 17.5 and 7.1% respectively. Both SR2 methods estimated the minimum E T more accurately compared to the maximum. The SRDT method was more in agreement with K c approach. Surface renewal is robust, less expensive than other micrometeorological techniques and a reliable method for deriving evapotranspiration of soybean when crop coefficients are problematic. Highlights: Evapotranspiration of soybean was estimated using the surface renewal (SR) method. The crop coefficient ( K c ) approach was used to evaluate surface renewal performance. SR and K c approach estimates of evapotranspiration were almost indistinguishable. Surface renewal is an alternative method to the crop coefficient approach.