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Research seeks soil pH answers in wheat fields followed with cotton

Brian Arnall discusses research trials and results.

Donald Stotts

August 14, 2020

Ongoing research into soil pH is providing insight for wheat producers considering planting cotton in their crop rotation.

While producers recognize that the lack of agricultural liming in traditional wheat fields can make cotton production challenging, specifics as to how different soil pH levels might affect the second crop’s performance have been unknown, said Brian Arnall, OSU Extension precision crop nutrient management specialist.

“The Oklahoma Cotton Support Group has been helping us perform research trials the past few years looking at cotton yield, quality and overall production,” said Arnall, who recently spoke about the research trial on OSU Extension’s agricultural television show SUNUP.

“In recent years, cotton production has expanded into regions that traditionally grew wheat, which can grow in low soil pH realms and do well in terms of yield. We’ve been studying two different cultivars across a range of soil pH levels.”

Soil pH – a measure of acidity and alkalinity – can range from zero to 14, with the optimal range for most plants falling in the 5.5-7.0 zone.

Important takeaways include:

  • A soil pH level of 4.0 resulted in fewer than one cotton plant per 10 row feet.

  • A soil pH level of 5.0 exhibited six to eight plants per 10 row feet, but quality was poor and plants were short.

  • The transition mark in terms of unacceptable and acceptable plant performance was seen at the 5.5. soil pH level.

“This trial is a drastic example of why soil testing is so important. Good soil management is a must to successfully grow a good crop. Profit margins are too tight for most producers to risk not knowing the soil profiles of their fields,” Arnall said.

It takes 200-300 days for agricultural liming to effectively change soil pH in a field. OSU specialists recommend the following:

  • Harvest the wheat crop in June or early July.

  • Take soil samples and have them tested.

  • Get the analysis and immediately apply the necessary lime, giving it a chance to work over the fall and winter. Then, come spring, plant the cotton.

“Remember that the rate of change from liming is heavily dependent on available soil moisture,” Arnall said. “Typically, the farther west one goes in the state, the longer it will be to see full advantage because of lesser rainfall amounts.”

Source: is OSU, which is solely responsible for the information provided and is wholly owned by the source. Informa Business Media and all its subsidiaries are not responsible for any of the content contained in this information asset.

About the Author(s)

Donald Stotts

Communications Specialist, Oklahoma State University Agricultural Communications Services

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