If ever there was a year built for conducting irrigation field research in the lower Southeast, it was 2010, with record-breaking heat and prolonged drought in many areas.

As growers struggle to meet the dual demands of providing enough water for their crops and maintaining efficiency, subsurface drip irrigation is attracting more interest. In one trial conducted by Auburn University in southeast Alabama, corn yields this past year were doubled in subsurface drip-irrigated fields versus dryland fields.

According to a recently published report, a subsurface drip irrigation (SDI) demonstration was installed on the Wiregrass Research Center (WREC) in Headland, Ala., in late spring/early summer 2009. The site has slightly rolling topography with one or two terraces.

Growers are encouraged to visit this location throughout the year and see how subsurface drip irrigation works on the light, sandy soils of southeast Alabama.

Six plots, each 950 feet long by 48 feet wide, were established for a three-year irrigated and rainfed (dryland) rotation of corn, cotton and peanuts. The six plots are grouped into three two-plot blocks. Each block has a 16-row rainfed (dryland) plot and a 16-row irrigated zone.

Each irrigation zone has 15 mil. drip tape lateral buried between every other row at 15 inches deep (eight drip laterals per irrigation zone). John Deere Auto Steer was used during installation to allow future drip tape location. With 0.26 gallons per hour (GPH) emitters spaced every 2 feet along tape length, design tape flow rate was 0.0022 gallons per minute (GPM) per foot. Each 1.07 acre irrigated zone requires 16.81 GPM (15.73 GPM per acre).

Irrigation water is supplied by a 3-horespower submersible pump with pressure tank control, installed in a farm pond approximately one half mile from the site. A 2-inch time and pressure automatic cleaning filter provides clean water to the three irrigated zone control heads. An irrigation controller for zone control, a Watermark Monitor with Watermark soil moisture sensors, and a tipping bucket rain gauge were installed.

A low power field radio was connected to the Watermark Monitor to allow remote reading of received rain, soil moisture and irrigation operation from a desktop computer located in the WREC offices about 1,200 feet away. MoisMis2020, an Xcel-based irrigation scheduling program using crop growth curves, rainfall and Watermark soil moisture feedback was to be used to schedule irrigation for the three crops.

This report talks about rainfall, irrigation and corn yield results from the first two years of the demonstration.

In 2009, corn was planted on April 24, about three weeks later than normal. Drip tape laterals were installed April 23 but installation of manifolds, control station, main lines and pond water pumping station occurred over the next two months. Soil moisture sensors were not installed due to system start-up problems.

Manifold/lateral leaks were repaired and the first irrigation, a four-hour operational test, occurred on June 17, 2009.