Cotton growers may be leaving money on the table if they wait too long to begin irrigating their crop, says Darrin Dodds, assistant Extension professor of plant and soil sciences at Mississippi State University.

“A one week difference between initiating furrow irrigation can make a difference of 50 pounds in yield — at $1 to $1.50 cotton, that’s $50 to $75 per acre you’re potentially missing,” he said at the annual conference of the Mississippi Agricultural Consultants Association.

“In 2010, when weather was very dry during the bloom initiation period, University of Arkansas personnel saw a 120 pound difference between starting irrigation one week prior to bloom versus at or after bloom.”

 Water management is one of the most important aspects of cotton production — but one of the least understood, Dodds says.

“With concerns about drawdown of the Delta’s alluvial aquifer and increasing regulation of water use for crop irrigation, we need to use water as efficiently as possible to achieve maximum production.”

To do that, he says, it’s important to understand how cotton uses water.

“Once cotton reaches peak bloom, water use increases significantly. But commonly, producers wait until blooms have begun to appear to begin watering.”

Arkansas research in which irrigation was initiated two weeks prior to bloom, one week prior to bloom, and one week after bloom has shown the one week before bloom scenario to be the most efficient, Dodds says.

“Looking at three years of data, initiating irrigation one week before bloom was consistently higher in yield than initiating irrigation during the first week of bloom by approximately 50 pounds. Terminating irrigation at 5 percent to 10 percent open bolls also was the most effective over three years. If you continue to water beyond that point, added moisture under a lush canopy can increase the risk of hard lock, boll rot and other problems.