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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Soil, Water & Air Resources Research » Research » Publications at this Location » Publication #332920
Title: Long-term application of the Crop Water Stress Index in Midwest agro-ecosystems

Author
item DOLD, CHRISTIAN - Orise Fellow
item Hatfield, Jerry
item Prueger, John
item Sauer, Thomas - Tom
item BÜYÜKCANGAZ, HAKAN - Orise Fellow
item RONDINELLI, WESLEY - Texas A&M University

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/9/2017
Publication Date: 11/15/2017
Citation: Dold, C., Hatfield, J.L., Prueger, J.H., Sauer, T.J., Büyükcangaz, H., Rondinelli, W. 2017. Long-term application of the Crop Water Stress Index in Midwest agro-ecosystems. Agronomy Journal. 109(5):2172-2181. https://doi.org/10.2134/agronj2016.09.0494.
DOI: https://doi.org/10.2134/agronj2016.09.0494

Interpretive Summary: Agricultural land in the Midwestern US is largely used for rainfed corn and soybean production. The native ecosystems in this region predominantly consist of tallgrass prairie. Water stress can occur in summer which can affect carbon assimilation, biomass production and yield of those agro-ecosystems. In addition, high spring precipitation can result in very wet to water logged soil conditions, especially on cropland. The Crop Water Stress Index (CWSI) was calculated for corn, soybean, and reconstructed tallgrass prairie in Central Iowa from July/August 2006/2007 - 2015. Carbon uptake at all three sites decreased as the CWSI increased, showing that water stress adversely affected carbon assimilation. Prairie CWSI significantly decreased with increasing soil water content. CWSI of corn and soybean increased with increasing soil water content, indicating that the CWSI concept not only applies to drought, but also to wet soil conditions. The CWSI can be applied to measure crop water stress in rainfed corn and soybean production as well as native grasslands. Thus, it is a possible tool for farmers or extensionists to evaluate water stress of both drought and water logging in the Midwestern US.

Technical Abstract: Agricultural land in the Midwestern US is largely used for rainfed corn (Zea mays L.) and soybean (Glycine max (L.) Merr.) production. The native ecosystems in this region predominantly consist of tallgrass prairie. Water stress can occur in summer which can affect carbon assimilation of those agro-ecosystems. In addition, high spring precipitation can result in very wet to water logged soil conditions. In this study, the theoretical Crop Water Stress Index (CWSI) was calculated using eddy flux measurements coupled with infrared thermometer sensor data for corn, soybean, and reconstructed tallgrass prairie in Central Iowa from July/August 2006/2007 - 2015. The relationship between CWSI and eddy flux derived net ecosystem production (NEP), actual evapotranspiration (ET), and volumetric water content (VWC) at 10 cm soil depth was investigated. Average CWSI values varied greatly among years and agroecosystems from 0.1 to 1.1. The NEP significantly decreased at all three sites with increasing CWSI (p < 0.05), showing that water stress adversely affected carbon assimilation. Prairie CWSI significantly decreased with increasing VWC (r = -0.45, p < 0.001). CWSI of corn and soybean increased with increasing VWC (p < 0.05), indicating that the CWSI concept not only applies to drought, but also to wet soil conditions. The CWSI decreased with increasing ET of soybean (r = -0.24, p < 0.001) and prairie (r = -0.29, p < 0.001), which is probably related to evaporative cooling. The theoretical CWSI can be applied to measure crop water stress in rainfed corn and soybean production as well as native grasslands.