What is in this article?:
- Rio Grande Valley farmers offered limited surge valves at extreme discount
- Study indicates technology's value
- How surge irrigation works
- Surge valve incentives in South Texas.
- South Texas farmers are looking for cost-effective ways to make every drop count.
- Surge irrigation uses a surge controller butterfly valve placed in the center of the top of the field with gated pipe leading out of the valve going both directions.
How surge irrigation works
Surge irrigation uses a surge controller butterfly valve placed in the center of the top of the field with gated pipe leading out of the valve going both directions. The valve works by oscillating water from one side of the valve to the other at determined intervals.
The alternating flow of water on each side of the valve causes an intermittent wetting and soaking cycle in the irrigated furrow. This causes soil particles to settle to the bottom of the furrow and can reduce the water intake rate of the soil. With a reduced intake rate, the water can advance down the furrow faster giving the field a more uniform water application, while requiring less water for an adequate irrigation.
"If it takes 12 hours to run 100 rows (furrows) utilizing constant flow irrigation, with a surge valve it can be set up to take 24 hours to run 200 rows, first to one side of the valve and then the other side of the valve or irrigation line. This breaks the water application up and allows the surface of the field to seal rather than having so much infiltration or evaporation," McLemore explained.
He says tests have discovered that surge valve irrigation not only lowers the infiltration rate but also helps on the tail water so excess water doesn't run off the end of the field, meaning it takes less water to complete an irrigation cycle.
Another benefit of surge irrigation is that valves controllers allow the grower to choose the durations of the irrigation oscillations from one side of the field to the other.
With the upcoming standards regarding water quality, using best management practices in irrigated fields to reduce soil loss, nutrient loss, and water usage, is becoming more important. Studies of surge irrigation have shown significant benefits to increased irrigation efficiency, yield maintenance while using less water, reduced nitrogen leaching in some fields, and reduced sediment loss.
While conventional irrigation and surge irrigation may produce equivalent yields in the end, trials indicate surge valves used half the amount of water over the entire irrigation season compared to conventional irrigation to achieve the same results.
"This could help Valley growers avoid purchasing out of district water during dry years or when adequate water is just not available," McLemore added.
Water officials say the 32 growers selected to participate in the current surge valve program must agree to attend one of two scheduled meetings where proper use of surge valves will be offered if they want to receive the full cost discount of the valves. These programs will be offered Tuesday, Sept. 17, and/or Wednesday, Sept. 18. Both will be held at the Rio Grande Center for Ag Water Efficiency, located next to the Harlingen Irrigation District’s river pumping plant.
"What we hope to accomplish with this program is to introduce surge valve technology to more local growers. Once the technology is employed in a real farm setting, others will hear about it and this in turn could encourage other growers to look at the technology as a way to conserve water and even cut irrigation costs," McLemore said.
The Rio Grande River Water Authority applied for the grant to support this program after field demonstrations showed that using surge valves in furrow irrigation can significantly reduce water consumption across a variety of crops. The demonstrations — conducted by the Texas Project for Ag Water Efficiency (Texas AWE) — documented water savings of up to 52 percent in sugarcane, 31 percent in seed corn, and 28 percent in cotton.
Growing sugarcane in the Lower Rio Grande Valley uses some 252,000 acre-feet of water per year, and irrigated cotton about 111,000 acre-feet per year. Based on Texas AWE findings, using surge valves to irrigate these crops could save around 110,000 acre-feet of water per year in the region, an amount equal to about 40 percent of current municipal demand in the entire Valley.
Interested growers can contact any irrigation district office in the valley for more information or can call Karen Ford at Water PR at 512.477.5445, or Tom McLemore, Harlingen Irrigation District at 956.367.6599.