11-Year Study of Cropping System Influence on Subsurface Drainage Flow in Central Iowa
Abstract
People have converted over 99% of Iowas original land cover of wetlands and tallgrass prairie to tile-drained crops: first to perennial cereal crops and then to an annual corn/soybean rotation after World War II. This massive land use change has increased streamflow in the Mississippi River Basin and increased flood and drought severity, now exacerbated by anthropogenic climate change. Restoring living plant cover duration past the crop growing season has the potential to increase plant water use and soil water retention, thereby mitigating downstream vulnerability to flooding and improving crop resiliency to drought. Thus, our study quantifies the annual drainage volume on a plant cover duration range from fully perennial (i.e. prairie), through annual (i.e. corn/soy) with cover crops, to fully annual plant communities from 2010-2020. The Comparison of Biofuel Systems (COBS) experiment in Central Iowa has 6 treatments: corn and soybean years of a corn/soy rotation, continuous corn, corn with winter rye cover crop, fertilized prairie, and unfertilized prairie. We found significant differences in drainage between treatments, with corn and soybean systems exhibiting higher drainage than the cover crop or prairie treatments. Drainage volume also varied with precipitation, increasing in wetter years and decreasing in drier years. Further, drainage response to precipitation depended on treatment, with drainage in unfertilized prairie exhibiting lower sensitivity to rainfall than the corn and soybean treatments. Drainage generally declined over time. The trajectory of that decline depended on treatment, notably in the shift of the unfertilized prairie from one of the lowest drainage volumes to one of the highest. Plant community and soil structure establishment likely explain observed differences in drainage. Overall, our results indicate that cover crop usage in agriculture can mimic prairie hydrology and drought resilience.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.H52I..05S