A Texas A&M AgriLife Research study looked at irrigation timing to maximize water-use efficiency and yields. (Texas A&M AgriLife photo by Kay Ledbetter.)

Cotton is sensitive to water stress at different growth stages, needing water at specific times to produce a high-yielding crop. A Texas A&M AgriLife Research study investigated the best strategies to improve irrigation water-use efficiency while maintaining high yields.

“Evaluation of crop-growth-stage-based deficit irrigation strategies for cotton production in the Southern High Plains,” was authored by AgriLife Research scientists Srinivasulu Ale, Ph.D., geospatial hydrologist, and Sushil Himanshu, Ph.D., postdoctoral research associate, both in Vernon, and James Bordovsky, senior agricultural engineer, Halfway, along with and Murali Darapuneni, New Mexico State University.

The study was published in Agricultural Water Management Journal’s special issue on Managing the Ogallala.

Himanshu said the study should help farmers make better decisions that can result in higher seed cotton yields using the most efficient irrigation strategies. At the same time, these strategies will conserve the Ogallala Aquifer as a water resource for generations to come.

Researchers focused on irrigation strategies based on cotton’s five growth stages, with certain stages irrigated more and others less. The CROPGRO-Cotton module available in the Decision Support System for Agrotechnology Transfer Cropping System Model was used. This crop growth-simulation model allows testing and analysis of different irrigation scenarios.

The Southern High Plains are hot, dry and often windy with water shortages due to the region’s low rainfall and reliance on underground water. Cotton-boll size and count are greatly affected by the amount and timing of irrigation as well as rainfall and air temperature.

Additionally, water districts in the area have imposed restrictions on groundwater pumping to help conserve the Ogallala Aquifer. Depletion of the aquifer has been occurring at an alarming rate since the 1950s when farmers began large-scale water pumping for crop irrigation.

“Following the suggested strategies, farmers can have better control over crop growth and yield and enhance irrigation water-use efficiency,” Ale said. “The peak bloom growth stage was found to be the most sensitive stage to water stress and imposing water deficit during this stage resulted in the lowest seed cotton yield.”

Conversely, elimination of irrigation during the early and late-season growth stages had little effect on seed cotton yield and irrigation water-use efficiency.

“We also determined that reducing early season irrigation potentially increased cotton root growth,” Bordovsky said. “This helps plants have a stronger resilience to water shortages in later growth stages and increased seed cotton yield.”

Cotton Incorporated and the Ogallala Aquifer Program funded this study.

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