Cover crops and irrigation impacts on corn production and economic returns

Authors: RUSSELL, DILLON - Mississippi State University; SINGH, GURBIR - University Of Missouri; QUINTANA-ASHWELL, NICOLAS - Mississippi State University; KAUR, GURPREET - University Of Missouri; GHOLSON, DREW - Mississippi State University; KRUTZ, JASON - Mississippi State University; NELSON, KELLY - University Of Missouri

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/20/2024
Publication Date: 3/5/2024
Citation: Russell, D., Singh, G., Quintana-Ashwell, N., Kaur, G., Gholson, D., Krutz, J., Nelson, K.A. 2024. Cover crops and irrigation impacts on corn production and economic returns. Agricultural Water Management. https://doi.org/10.1016/j.agwat.2024.108739.
DOI: https://doi.org/10.1016/j.agwat.2024.108739

Interpretive Summary: An increase in irrigated crop acreage along with more frequent droughts during the agricultural growing season have caused a decline in groundwater levels for the Mississippi River Valley Alluvial Aquifer in the Mississippi Delta region. A field experiment was conducted from 2019 to 2021 to determine if combinations of irrigation scheduling thresholds and cover crops (CCs) could improve corn production, water productivity (WP), irrigation water use efficiency (IWUE), and net economic returns. The irrigation thresholds used for irrigation scheduling were a wet threshold, a dry threshold, and no irrigation. The CC treatments were cereal rye , hairy vetch, wheat-radish-turnip mix, and no cover crop. In 2020, corn yields were reduced by 9–26%in CC treaments compared to no cover crop. In 2021, wet irrigation threshold treatments had 8% higher corn yield than no irrigation and 9% higher than the dry irrigation threshold treatments, respectively. The no irrigation treatments showed higher WP than either the dry or wet irrigation thresholds. For the CC treatments hairy vetch had higher WP in year two of this study. Hairy vetch under the dry irrigation threshold had higher IWUE than all other treatments. Average across both years, the no-CC treatments generated $167, $340, and $58'ha-1 more under the wet, dry, and no irrigation treatments, respectively. Water conservation was affected by both CC selection and irrigation management. This research will help producers make informed decisions for irrigation, scheduling, and cover crop usage.

Technical Abstract: Increases in irrigated crop acreage and frequent droughts during the growing season have caused continual groundwater decline of the Mississippi River Valley Alluvial Aquifer in the Mississippi Delta region. A field experiment was conducted from 2019 to 2021 to determine if combinations of irrigation scheduling thresholds and cover crops (CCs) could improve corn (Zea mays L.) production, water productivity (WP), irrigation water use efficiency (IWUE), and net returns. The irrigation thresholds used for irrigation scheduling were a wet threshold (-40 kPa), a dry threshold (-90 kPa), and no irrigation. The CC treatments were cereal rye (Secale cereale L.), hairy vetch (Vicia villosa R.), wheat (Triticum aestivum L.)-radish (Raphanus sativus L.)-turnip (Brassica rapa L.) mix, and no cover crop. In 2020, CCs reduced corn yield by 9–26% compared to no cover crop. In 2021, wet irrigation threshold treatments had 8% and 9% higher corn yield than no irrigation and dry irrigation threshold treatments, respectively. No irrigation treatments showed higher WP than dry and wet irrigation thresholds, while hairy vetch had higher in WP among CC treatments in year two of this study. Hairy vetch under the dry irrigation threshold had higher IWUE than all other treatments. The no-CC treatments generated $167, $340, and $58'ha-1 more under the wet, dry, and no irrigation treatments, respectively, when averaged over both years. Water conservation was affected by CC selection and irrigation management.