Can crop rotations facilitate surface water – groundwater connectivity to maximize yield during drought?

Authors: Schreiner-Mcgraw, Adam; WOOD, JEFFREY - University Of Missouri

Submitted to: American Geophysical Union Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/4/2022
Publication Date: 12/12/2022
Citation: Schreiner-McGraw, A.P., Wood, J.D. 2022. Can crop rotations facilitate surface water – groundwater connectivity to maximize yield during drought? [abstract]. American Geophysical Union Meeting Abstract. Paper 1163208.

Interpretive Summary:

Technical Abstract: Rainfed corn (Zea mays) and soybean (Glycine max) rotation is the primary agricultural system in the Midwest United States and covers millions of hectares of land. One of the challenges is that rainfed agricultural systems are particularly susceptible to growing season droughts that can cause catastrophic crop losses of sufficient magnitude to influence global markets, which occurred in 2012. Climate models suggest that precipitation is shifting to occur less during the summer, which makes these droughts more likely. In regions with heavily eroded topsoil, such as the claypan region of Missouri and Illinois, the impacts of drought are amplified due to the low moisture holding capacity of the shallow soils. In the claypan region, a layer of high clay (>50% clay) acts as an impermeable barrier and prevents interactions between the groundwater and soil water pools. We therefore evaluated a cropping system that includes a 2-year hay crop thought to create root channels in the claypan layer which may allow water to flow through it. This should facilitate interactions between shallow groundwater and soil water, allowing for a larger effective water storage capacity, which could serve to buffer crops during drought. We compared this system under aspirational management, to a field with a conventional corn-soybean rotation. We used a combination of eddy covariance, sap flow, and soil moisture measurements to evaluate crop water use over the 2022 growing season, which included periods with strong soil and atmospheric drought. Relationships between vapor pressure deficit and crop water use were used during the drought period to evaluate if the extended hay rotation allowed groundwater to supplement surface soil moisture. Additionally, we used a water balance approach to evaluate the contribution of groundwater to plant water use at both the conventional and the extended hay rotation fields. Results from this study may help farms build more resilience to changing climate conditions where droughts are more frequent.