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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Water Management and Systems Research » Research » Publications at this Location » Publication #345839

Research Project: Improving the Sustainability of Irrigated Farming Systems in Semi-Arid Regions

Location: Water Management and Systems Research

Title: Crop water use and crop coefficients of maize in the US Great Plains

Author
item Trout, Thomas - Collaborator
item Dejonge, Kendall

Submitted to: Journal of Irrigation and Drainage Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/29/2018
Publication Date: 4/12/2018
Citation: Trout, T.J., Dejonge, K.C. 2018. Crop water use and crop coefficients of maize in the US Great Plains. Journal of Irrigation and Drainage Engineering. 144(6):04018009. doi:10.1061/(asce)ir.1943-4774.0001309.
DOI: https://doi.org/10.1061/(ASCE)IR.1943-4774.0001309.

Interpretive Summary: Maize water use was measured by water balance in a 6 year field trial in the west-central U.S. Great Plains. About 10% of seasonal crop evapotranspiration was estimated to be surface evaporation, and seasonal crop evapotranspiration averaged 68% and 82% of tall (alfalfa) and short (grass) reference evapotranspiration, respectively. Derived basal alfalfa reference crop coefficients matched published values during crop development, but during reproductive growth exceeded published values by about 10%. Derived basal crop coefficients were linearly related to crop canopy ground cover, providing opportunities to scale canopy to water use.

Technical Abstract: Maize water use was measured by water balance in a 6 year field trial in the west-central U.S. Great Plains. Seasonal water use of the 102 day maturity class variety varied from 616 to 774 mm with an average of 666 mm. About 10% of the seasonal crop evapotranspiration from the drip-irrigated crop was estimated to be evaporation from the wet soil surface following precipitation or irrigation. Seasonal crop evapotranspiration averaged 68% of tall (alfalfa) reference evapotranspiration and 82% of short (grass) reference evapotranspiration. Derived basal alfalfa reference crop coefficients, Kcb, matched ASCE Manual of Practice (MOP) 70 values (Jensen and Allen 2016) fairly well during crop development, but were about 1.05 during reproductive stage which exceeded MOP values by about 10%. Short reference Kcb values matched values published in FAO-56 (Allen et al. 1998) fairly well. The derived basal crop coefficients were linearly related to crop canopy ground cover which provided an excellent way to scale Kcb during both crop development and maturation stages.