New Waves April 2009

Breaking news about water resources research and education in Texas

AgriLife researchers compare tillage operations on runoff quality

Dr. Paul DeLaune, environmental soil scientist at the Texas AgriLife Research and Extension Center at Vernon, is studying the impact of different tillage operations in dual-use wheat on runoff quantity, water quality, and nutrient loss.

Much of Texas' wheat may be grazed as part of a dual-use crop, but many fields are still using conventional tillage, which may not efficiently capture rainfall; a key to economic success in a semi-arid environment, said DeLaune.

Each year, depending on market conditions, up to 75 percent of wheat planted in Texas may be grazed, and of that, 95 percent is under conventional tillage, DeLaune said.

He said tillage operations can increase soil compaction, thereby increasing runoff.

"There is a perception among some producers considering no-till production that using no-till in dual-use wheat production will increase compaction and therefore reduce water infiltration and decrease yields," he said.

DeLaune sought to determine whether this perception was valid. His study applied conventional-till, no-till, and no-till with aerator offsets to graze-out and graze plus grain production systems.

Months later, DeLaune applied a runoff-producing event to the crop with simulated rainfall of 2.75 inches per hour showered over the crop and allowed to continue until one-half hour after runoff started. The runoff water was collected, measured, and analyzed for quantity and quality.

DeLaune said the runoff came quickest, in the highest quantity, and with the most soil erosion from the conventional-tilled plots. Also, the total amounts of ammonium and phosphorous in the runoff water were higher from the conventional-tilled plots.

There was no statistical difference in runoff volume, soil erosion, and nutrient runoff amounts between the no-till plots and the aerated treatments, he said.

These initial results show that the use of an AerWay aerator may not be economical, based solely on soil and water conservation. Grazing effects and grain yields may indicate otherwise as the study continues, DeLaune said. Runoff quantity, water quality, and yield data will continue to be collected over the next two years.

This study is supported by the Texas Wheat Producers Board.

Portions of this story are featured in the AgNews release "Researchers to determine if aeration reduces compaction, runoff on no-till fields." Read the entire AgNews release.

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