Deficit drip irrigation should be a targeted approach by stressing the plant only at times when the least damage is done.

“The best times to deficit irrigate are early in the season before match head square and during the boll filling and maturation period in the late summer,” Hutmacher told the crowd.

“Do not greatly reduce water applications from mid square development through peak bloom; typically from mid-June into mid-July. If you do, this increases the chances of water stress-related fruit (yield) losses.”

This water management technique can save 3-4 inches of water or more in most years; water now available for other crops or to spread across more production acres.

“The fiber length, strength, and micronaire numbers still look good with this level of deficit irrigation and should not be affected to the point of a discounted price level,” Hutmacher said.

Hutmacher’s trials included nine varieties of Pima and Acala cottons. Deficit irrigation had about the same relative impact across all tested varieties, although there were varietal differences in attained yields. Field studies will continue this year.

When deficit drip irrigating cotton, Hutmacher said the effective soil volume that root systems explore for water and nutrients can be greatly reduced. It is important that growers supply nutrients to the plant through drip fertigation to maximize the delivery to the root zone. Dry nutrient applications with drip are less effective.

Overall, as California growers brace for more water cutbacks, Hutmacher says, “Cotton will still have a place in California agriculture as it uses less water than corn and alfalfa, and not much more water than a high yielding wheat field.

Deficit irrigation is one method to help growers manage the water shortage and still produce a high quality cotton crop.