Eddy covariance quantification of corn (Zea mays L.) water use and yield responses to irrigations on farm-scale fields

Authors: Anapalli, Saseendran; SRINIVASA, PINNAMANENI - Oak Ridge Institute For Science And Education (ORISE); Reddy, Krishna; SIGNH, GURBIR - Mississippi State University

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/30/2022
Publication Date: 5/30/2022
Citation: Anapalli, S.S., Srinivasa, P.R., Reddy, K.N., Signh, G. 2022. Eddy covariance quantification of corn (Zea mays L.) water use and yield responses to irrigations on farm-scale fields. Agronomy Journal. 114(4):2445-2457. https://doi.org/10.1002/agj2.21130.
DOI: https://doi.org/10.1002/agj2.21130

Interpretive Summary: The Mississippi River Valley Aquifer is fast drying up as the current water withdrawals from it for crop irrigations in the region far exceed the aquifer’s natural recharge rates. Reducing the amount of water pumped is essential for sustainable crop production and saving the aquifer from further decay. Scientists in the Sustainable Water Management Research Unit, USDA ARS, Stoneville, MS, and the National Center for River Valley Alluvial Aquifer, Mississippi State University, Stoneville, MS, investigated corn productivity in clay soil in response to irrigations applied through all furrows, skipping a furrow, and rainfed (unirrigated) conditions. These studies were conducted on farm-scale fields (15 ha). Using about sixty percent of the water applied in all-furrow irrigations, corn harvested in skip-furrow systems was about 4% higher. However, rainfed systems produced about 14% less corn yields on average. The study established that irrigating corn through skip-furrows yields better than irrigating through all-furrows, potentially saving about forty percent of the water pumped out of the aquifer. The farm-scale plots used in this study give us better confidence to recommend the skip-furrow irrigation system to replace conventional all-furrow systems in the region to check further aquifer decline.

Technical Abstract: he current rate of groundwater extractions for crop irrigation from the MIssissippi River Valley Aluviald Aquifers far exceed the aquifer's’ natural recharge levels, hence the sustainability of irrigated agriculture in the Lower MIssissippi regions is in is in danger. Surface flood irrigations applied through furrows dominate row-crop irrigation scenarios in many regions worldwide. In this study, corn (Zea mays L.) yield and consumptive water use (ET, evapotranspiration) in a conventional all-furrow irrigation (FI) were compared against irrigations applied through alternate furrows (SFI, targeted to irrigate with about half of the water applied in FI) and rainfed (RF) systems in large farm-scale fields (10 ha) in 2017 and 2019 in clay soil in the Lower Mississippi Delta region (LMD), USA. Crop ET was monitored using the eddy covariance (EC) method. The average corn yield in the SFI was significantly (12.1 Mg ha-1) higher (4.9%) than in the FI (11.7 Mg ha-1). Corn yield in RF (10.2 Mg ha-1) was significantly lower (10.7%) than in the FI. However, the leaf area index (LAI) measured in SFI was slightly lower than in FI. Seasonal average ET was 556, 573, and 540 mm in FI, SFI, and RF treatments, respectively. The average water use efficiencies (WUE, ratio of grain yield to ET) were 0.021, 0.021, and 0.019 Mg ha-1 mm-1, respectively (10.5 % lower in RF than FI and SFI). This investigation revealed that practicing SFI in corn-based cropping systems can return grain yields comparable to the same crop grown under the conventional FI, saving about 40% of irrigation water. The farm-scale studies conducted in this investigation give better confidence to recommend SFI to replace conventional FI systems in the region for water conservation in cropping systems. Further investigations may be needed to evaluate the viability of SFI in other contrasting soils and climates and recommend the system for adoption by the farming community.