Location: Cropping Systems and Water Quality Research
Title: Climate change impacts on plant water availability in a rainfed cropland with shallow soils in the U.S. Corn BeltAuthor
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Schreiner-Mcgraw, Adam |
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Baffaut, Claire |
Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only Publication Acceptance Date: 11/13/2024 Publication Date: 11/13/2024 Citation: Schreiner-McGraw, A.P., Baffaut, C. 2024. Climate change impacts on plant water availability in a rainfed cropland with shallow soils in the U.S. Corn Belt. ASA-CSSA-SSSA Annual Meeting Abstracts. Paper No. 159685. Available: https://scisoc.confex.com/scisoc/2024am/meetingapp.cgi/Paper/159685 Interpretive Summary: Technical Abstract: In the rainfed cropland of the U.S. Corn Belt, understanding crop water use is important to adapt management practices to a changing climate. Changing precipitation patterns are expected to affect distributions of soil water, vadose zone water, and groundwater in complex ways. In this presentation, we evaluate where in the root zone crops obtain water from. To do this, we co-locate measurements of crop water use, soil moisture profiles, and groundwater level at three locations within a field (ALT field) with a restrictive soil layer to quantify where in the subsurface crops draw water from. We found that crops primarily drew water from the topsoil (top 10-30 cm) and groundwater, accounting for an average of 27% and 53% of growing season water use, respectively. Groundwater use was calculated as a residual of the water budget, so measurement uncertainty likely biased our results. Additionally, there is considerable variability between the three locations, likely due to differing water table depths. To test if our results are robust over a longer period, we calculated field-scale water budgets using measurements of precipitation, evapotranspiration (ET), and runoff at the ALT field, managed with alternative practices to boost sustainability, and a field following the prevailing management practices in the region (PRV). We found that both fields had considerable ET sourced from groundwater; an average of 71 mm and 98 mm per growing season for the PRV and ALT fields, respectively. Next, we built a process-based hydrologic model of the ALT field using the ParFlow.CLM modeling system that was able to capture the hydrologic processes with a high degree of accuracy. We use downscaled climate change scenarios to force the model and discuss the impacts on water availability in different soil layers. Our results highlight the importance of groundwater in rainfed croplands in the U.S. Corn Belt. |