New Waves March 2009

Breaking news about water resources research and education in Texas

AgriLife Research drip irrigation project yields promising results

The Texas AgriLife Research Station near Chillicothe is conducting a study to develop conservation tillage and water management strategies that enhance crop-stand establishment, water-use efficiency, and yield in subsurface drip-irrigated cotton production in the Rolling Plains.

In the first year of the three-year study, Dr. John Sij, AgriLife Research agronomist, was able to use subsurface drip irrigation to produce up to four bales of cotton per acre with less water than conventional irrigation methods, even though cotton trials suffered through hail and drought.

"We started out with good stands and then a hail storm in June knocked out 25 percent of the plants," Sij said. "Under drip, the plants came roaring back, and we still made two-and-a-half to three-bale cotton.

"Our yield monitor on our commercial harvester showed areas of production that hit four bales per acre. I think we would have had higher yields if we hadn't had the hail and the lost heat units."

Sij said the advantage of drip irrigation is putting more water on the field and efficiently supplying water directly to the roots of the plants. With the use of a low-pressure pump, electricity cost $1.69 per acre.

Another unexpected savings occurred due to the quality of the water pumped on the cotton crop. Water from the well used is high in nitrates, so the crop essentially received 35 pounds of free nitrogen put out with the irrigation water, Sij said. That's $1 per pound of nitrogen savings last summer.

Sij recommends producers check out the nitrate levels of irrigation water. "While we know we have other nutrients met by fertilization requirements, nitrates coming through the drip irrigation system directly feed the roots of plants, so it is 100 percent efficient," he said.

First year trials also revealed that 100 percent replacement of water lost by evapotranspiration delayed in some cases boll opening and harvesting. Evapotranspiration is the loss of water from the soil by evaporation and by transpiration from plants.

Sij and AgriLife researchers are additionally testing various tillage systems, including tilled bedded rows, reduced-tillage flat-planted rows, no-till flat-planted rows, and no-till rows planted into a terminated wheat cover crop.

Thus far, a no-till flat-planting at a 66 percent to 100 percent evaportranspiration replacement rate is favored.

Read the AgNews story about this project.

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