Effective irrigation scheduling to improve corn yield, net returns, and water use

Authors: SHELDON, KENDALL - University Of Tennessee; SHEKOOFA, AVAT - University Of Tennessee; MCCLURE, ANGELA - University Of Tennessee; SMITH, AARON - University Of Tennessee; MARTINEZ, CHARLES - University Of Tennessee; Bellaloui, Nacer

Submitted to: Agrosystems, Geosciences & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/2/2023
Publication Date: 12/6/2023
Citation: Sheldon, K., Shekoofa, A., McClure, A., Smith, A., Martinez, C., Bellaloui, N. 2023. Effective irrigation scheduling to improve corn yield, net returns, and water use. Agrosystems, Geosciences & Environment. 6:1-12. https://doi.org/10.1002/agg2.20449.
DOI: https://doi.org/10.1002/agg2.20449

Interpretive Summary: Improving irrigation management and optimizing its use will save money and achieve high production in corn. The objective of this study was to maximize profitable corn yield using variable rate irrigation technology and soil water sensors. A field study was conducted at the University of Tennessee Milan Research and Education Center, in 2020 and 2021. Total irrigation amounts (millimeter, mm) treatments (T1, T2, T3) were 139.7 (5.5 inch) (T1), 124.4 (4.9 inch) (T2), and 68.5 (2.7 inch) (T3) in 2020, and 62.2 (2.5 inch) (T1), 46.9 (1.8 inch) (T2), and 30.4 (1.2 inch) (T3) in 2021. Rain-fed treatment was used as control. All irrigation treatments resulted in a greater yield than the rain-fed treatment in 2020. The irrigation cost was the lowest ($41.1/ ha) in T3 compared to the highest ($83.8/ ha) in T1. Considering the distribution of rainfall during 2020 and 2021, T3 with the fewest scheduled irrigation events had the best yield with 13.0 and 3.5% higher yield than rain-fed plots, respectively in 2020 and 2021. Results indicate that more than half the amount of irrigation can be saved without compromising yield or economic returns. This research demonstrated that irrigation scheduling would help corn growers optimize water use efficiency and improve corn production.

Technical Abstract: Irrigated cropland in Tennessee continues to increase to sustain higher temperature and water-deficit. Corn (Zea mays L.) production is directly related to water availability. Inefficient irrigation scheduling can result in excessive or inadequate water application. The objective of this study was to maximize profitable corn yield using variable rate irrigation (VRI) technology and soil water sensors. A field study was conducted at the University of Tennessee Milan Research and Education Center, in 2020 and 2021. Total irrigation amounts (millimeter, mm) treatments (I-1, I-2, I-3) were 139.7 (I-1), 124.4 (I-2), and 68.5 (I-3) in 2020; and 62.2 (I-1), 46.9 (I-2), and 30.4 (I-3) in 2021. Rain-fed treatment was used as control. All irrigation treatments resulted in a greater yield than the rain-fed treatment in 2020. The experiment was a randomized complete block design. Early in the season four Meter Inc. ZL6 soil water loggers were installed to monitor soil water levels. Each logger had 4-sensor per each irrigation treatment at depths of 20 and 66 cm. Irrigation scheduling decisions were based on rainfall, sensor-depth, matric potential, and crop rooting zone. The plots were 34 × 36 m to account for irrigation transition area and to accommodate the commercial size harvest combine. All irrigation treatments yielded significantly greater than rain-fed (RF) plots in 2020. In 2021, all treatments yielded numerically greater than RF, but only I-3 yielded significantly higher than RF. The irrigation cost was the lowest at $41.1 ha-1 for I-3 compared to the highest for I-1 at $83.8 ha-1. Considering the distribution of rainfall during 2020 and 2021, I-3 with the fewest scheduled irrigation events had the best yield with 13.0 and 3.5% higher than RF. Results indicate that more than half the amount of irrigation can be saved without compromising yield or economic returns. Information obtained from this research would help corn growers optimize water use efficiency and improve corn production.