Farm Progress

Sub-surface irrigation could increase crop yield

Blair Fannin

July 6, 2010

3 Min Read

A Texas AgriLife Research sub-surface irrigation study could reveal ways that will lead to higher crop yields and save water annually.

Dr. Tom Cothren, AgriLife Research crop physiologist and professor at Texas A&M University in the department of soil and crop sciences, is leading a project that uses a drip system to deliver water to plants rather than traditional furrow irrigation.

"Sub-surface irrigation reduces water loss from evaporation that occurs from above-ground applications and places water in the root zone where the crop can make most efficient use of its presence,” Cothren said. “This system also eliminates runoff associated with furrow irrigation."

The benefits are more uniform application of water to a specific crop, Cothren said.

"Efficient use of water to a crop is becoming more important with more demands for water in both the rural and urban areas."

"A drip system has the ability to reduce crop stress through frequent low-volume applications of water," said Cy McGuire, design consultant with Eco-Drip Irrigation, part of the research project team.

With expanding populations in both urban and rural areas, there will be more demands by municipalities on water use in the future, scientists said. The less water used by producers, the more producers will add to their bottom line with minimal investment, according to researchers.

The 8-acre field plot in College Station is part of several studies involving Texas A&M graduate students in the cotton physiology workgroup, Cothren said. The field is divided into 13 stations with 16 crop rows. Each row has a dripline or tape irrigation buried underneath the rows at a depth of 16 inches. A dripline is spaced every 40 inches with an emitter every 18 inches down the dripline. The emitters regulate the application of water at a desired rate.

"Each set of 16 crop rows will be able to water independently of each other through a computerized controller in order to apply varying amounts of water," McGuire said. "Each station will also allow the workgroup to vary the type and rates of chemical applications, such as fertilizer."

The study is also examining the loss of water due to evaporation on the soil surface. A benefit of a sub-surface irrigation system is the elimination of water runoff and the ability to reduce crop stress through frequent low-volume applications of water.

"Other forms of irrigation usually apply a higher volume of water at longer intervals, which could lead to water stress during the non-irrigating days," McGuire said.

John Rocconi, a graduate research assistant, said the investment under a normal production area would be $800 per acre to $900 per acre.

"There’s less loss due to runoff because the water is applied directly to the root system of the plant. I think it’s a good tool that will be moving toward acceptance across the board by farmers."

Rocconi said a farmer can plant now and apply nutrients, such as nitrogen, directly to the root system rather than having to wait for rainfall and save on production costs by "directly injecting nutrients at the well house."

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