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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 #424731
Research Project: Improving Crop Performance and Precision Irrigation Management in Semi-Arid Regions through Data-Driven Research, AI, and Integrated Models

Location: Water Management and Systems Research

Title: Crop water use and crop coefficients of sunflower in the U.S. central great plains

Author
item Trout, Thomas
item DeJonge, Kendall
item Zhang, Huihui

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/27/2025
Publication Date: 6/1/2025
Citation: Trout, T.J., DeJonge, K.C., Zhang, H. 2025. Crop water use and crop coefficients of sunflower in the U.S. central great plains. Agricultural Water Management. 316. Article e109583. https://doi.org/10.1016/j.agwat.2025.109583.
DOI: https://doi.org/10.1016/j.agwat.2025.109583

Interpretive Summary: Sunflowers are an important crop in dry regions like the U.S. Great Plains, where conserving water is crucial for farming. A long-term study looked at how much water sunflowers use during their growth cycle. It found that a significant portion of the water used by sunflowers is lost to evaporation from the wet soil after irrigation. Compared to other reference crops like alfalfa and grass, sunflowers use less water. The research also discovered a useful way for farmers to predict how much water their sunflowers need: by measuring how much ground the plant leaves cover. This method helps farmers avoid wasting water, which is important in areas where water is scarce. By optimizing irrigation, farmers can balance the needs of their crops with the need to conserve water.

Technical Abstract: Sunflower crop water use (evapotranspiration, ETc) was measured by water balance in a 9-year field trial in the west-central U.S. Great Plains. Seasonal ETc of the well-irrigated crops varied from 422 to 660 mm and averaged 523 mm. About 10% of the seasonal ETc with surface drip irrigation was estimated to be evaporation from the wet soil surface following precipitation or irrigation. Seasonal ETc averaged 68% of alfalfa (tall crop) reference evapotranspiration and 82% of grass (short crop) reference evapotranspiration. Derived mid-season basal alfalfa reference crop coefficients, Kcb, averaged 1.11 but varied among seasons from 0.94 to 1.34. Derived mid-season climate-adjusted basal grass reference crop coefficients averaged 1.25 and likewise varied seasonally. 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.