Evaluating growth-stage-based variable deficit irrigation strategies for improving yield and irrigation water use efficiency of grain sorghum

Authors: HIMANSHU, SUSHIL - Asian Institute Of Technology; ALE, SRINIVASULU - Texas A&M Agrilife; BELL, JORDAN - Texas A&M Agrilife; FAN, YUBING - Lanzhou University; SAMANTA, SAYANTAN - Texas A&M Agrilife; BORDOVSKY, JAMES - Texas A&M Agrilife; Gitz, Dennis; Lascano, Robert; Brauer, David

Submitted to: Irrigation Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/2025
Publication Date: 2/8/2023
Citation: Himanshu, S.K., Ale, S., Bell, J., Fan, Y., Samanta, S., Bordovsky, J., Gitz, D.C., Lascano, R.J., Brauer, D.K. 2023. Evaluating growth-stage-based variable deficit irrigation strategies for improving yield and irrigation water use efficiency of grain sorghum. Irrigation Science. 280. https://doi.org/10.1016/j.agwat.2023.108222.
DOI: https://doi.org/10.1016/j.agwat.2023.108222

Interpretive Summary: In the Texas High Plains hotter drier climate and diminishing irrigation water availability will limit sorghum yields. Methods are needed to extend the viability of irrigated sorghum production and the usefulness of the aquifer from which irrigation water is drawn. We hypothesized that timing irrigation applications and irrigation amounts based on sorghum growth stage could help maintain crop yields with less water, as compared to traditional irrigation scheduling methods. A team of scientists from the Asian Institute of Technology in Thailand, the Indian Institute of Technology in India, Texas A&M Agrilife, and the USDA-ARS Cropping Systems Research Laboratory in Lubbock, TX assembled mathematically modeled growth-stage-based irrigation management scenarios having different maximal water application rates. We found that by using growth-stage-based irrigation management during normal years growers could save up to 12% of irrigation water with only about a 1% loss in yield.

Technical Abstract: Recurring droughts, decreasing groundwater table in the Southern Ogallala Aquifer, and projected warmer and drier future climate pose major challenges for irrigated sorghum production in the Texas High Plains (THP) region. Managed deficit irrigation during different growth stages could improve sorghum yield and irrigation water use efficiency (IWUE). This study aimed to develop and evaluate growth-stage-based variable deficit irrigation (GSVDI) strategies for grain sorghum production in the THP region under different weather conditions (e.g., dry, normal, and wet years). The CERES-sorghum module within the Decision Support System for Agrotechnology Transfer (DSSAT) Cropping System Model that was evaluated based on a grain sorghum-cotton rotation experiment at Halfway, TX was used. Four growth stages of sorghum were considered, namely, emergence to panicle initiation (GS1), panicle initiation to boot (GS2), boot to early grain filling (GS3), and early to late grain filling (GS4). Long-term (1978-2019) simulations were conducted with combinations of four deficit irrigation levels (30%, 50%, 70%, and 90% evapotranspiration [ET] replacements) applied during the aforementioned growth stages, which resulted in 256 GSVDI scenarios. The GSVDI strategies with > 95th percentile of simulated sorghum yield and IWUE were identified as efficient irrigation scenarios. Among these efficient irrigation scenarios, the ideal GSVDI scenarios were identified for each weather category based on simulated sorghum yield and IWUE. The identified ideal GSVDI strategies were then compared with the control scenario (100% ET replacement in all growth stages). The results indicated that implementing GSVDI strategies could lead to significant irrigation water savings while maintaining higher sorghum yields. For example, S-64 (strategy of 30% ET-replacement in GS1 and 90% ET-replacement in GS2 to GS4) was identified as the ideal GSVDI scenario for normal years and it saves 12.2% of irrigation water with a minor loss (1% less) in grain sorghum yield as compared to the control scenario. Suggested GSVDI strategies from this study are very useful to optimize sorghum production while reducing groundwater withdrawals from the Ogallala Aquifer.