In semiarid farming regions where every drop of water counts, Texas AgriLife Research scientists say timing the application of available water is becoming more critical when it comes to irrigating cotton.

Jim Bordovsky, research scientist and agricultural engineer with AgriLife Research at Halfway, is collaborating on a project with Dana Porter and Jeff Johnson, Lubbock-based Texas AgriLife Extension Service agricultural engineering specialist and AgriLife Research economist, respectively. They recently completed the second year of a study to optimize water-use efficiency, lint yield and fiber quality of cotton under limited water conditions by evaluating a combination of irrigation amounts during different growth periods using Low Energy Precision Application or LEPA irrigation.

Bordovsky said the growth periods used in the study are generally described as: vegetative – from planting until very early bloom; reproductive – early bloom to just past peak bloom; and maturation – bloom to initial boll maturity. Their overall objective was to improve water efficiency in the semiarid Texas High Plains region by learning when a cotton crop responds best to combinations of limited and adequate water.

“Our irrigation water comes from the declining Ogallala Aquifer, where its availability for a given field can change dramatically within a single growing season,” Bordovsky said. “Shortages also occur when producers must divert water from cotton and give it to another crop, because that crop has reached a critical growth stage or simply because it’s worth more. Abrupt changes could also occur if irrigation wells are lost or annual irrigation volumes imposed by regulatory mandates are reached before the end of the growing season.”

Bordovsky said wise planning of irrigation based on a farm’s underground water resources, available water allowances and the region’s erratic rainfall will go a long way toward High Plains producers being productive in coming years.

“In situations where available water can’t meet the needs of the plant throughout the growing season, the irrigation-research community has recommended and producers have generally followed the practice of ‘banking water’ or attempting to partially fill the soil profile with preplant and/or early-season irrigations in April through June,” Bordovsky said.