Contributed by Colleen Tocci - Additional reporting by Elizabeth Ashby
Water is the most limiting factor in agriculture today. Without it, crops cannot thrive and flourish as expected, thus profitability decreases. In 2007 irrigation water for Florida agriculture accounted for about 48 percent of all ground and freshwater withdrawals, according to an article from UF/IFAS, “Sustainability of Agriculture in Miami-Dade County: Considering Water Supply.” But the availability of water is decreasing. Population increases, such as the 6 percent growth seen in Miami-Dade County from 2000 to 2006, according to the U.S. Census Bureau, are spurring the need for more consumable water forcing state and local authorities to find solutions for competing water demands.
For well over a decade, water conservation and use efficiency has been a subject of discussion by governmental agencies and advocacy groups. Phase II water restrictions have been implemented in many parts of Florida: some counties requesting that “low volume irrigation in agriculture be voluntarily reduced.” Many Florida growers have installed water meters to report water usage—a trend that promises to continue.
In 1996 the National Research Council stated that irrigation is essential to most agricultural production systems and was shown to significantly increase yield. For growers, their livelihoods depend on the use of an abundant amount of water. Or does it? What if growers could sustain a healthy and productive crop with 20+ percent less water and save energy and money by not running their irrigation pump as much and not using a penny’s worth of time to do it?
Soil surfactants could be a valuable tool.
What are soil surfactants?
Recent market research confirms that soil surfactants are not well known in the agriculture industry. Once an unfamiliar concept to golf course superintendents, soil surfactants are now used by more than 90 percent of them. So what is a soil surfactant and what does it do? This is where the confusion begins. A simple Internet search defines surfactants as surface active agents, and many refer to spray adjuvants as surfactants. While it is accurate to classify a spray adjuvant as a surfactant, most spray adjuvants enhance the spreading of water over a surface. They also differ from soil amendments such as limestone or gypsum, which create a chemical change in the soil by adding calcium to it.
Quality soil surfactants move water quickly off the surface of the soil and enable water to penetrate the soil and move laterally and vertically into the root zone. As the water moves through the soil, so do the pesticides and nutrients that the water carries; making them more available to the plant. This ability to influence where the water goes and what it does enables the grower to maximize the amount of water used.
Universities test the water
A number of research trials have been conducted by universities and independent researchers, as well as grower observations, to validate claims of a particular soil surfactant—IrrigAid Gold, manufactured by Aquatrols Corp. of America Inc., Paulsboro, N.J. It is a patented, alkoxylated polyol glucoether blend.
Most recently in the spring of 2008, Dr. Bielinski Santos of UF/IFAS conducted studies on tygress tomatoes at the Gulf Coast Research and Education Center, Balm, to monitor field moisture levels in the root zone. Plants were in single rows, 2 feet apart. Beds were 28 inches wide on top and 32 inches on the base covered with metalized mulch. Two quarts per acre of IrrigAid Gold were applied with a hydraulic injector at 0, 3 and 6 weeks after transplanting. The plots were irrigated with standard drip irrigation of 14 acre-inch/acre of water. Preliminary results indicated increased moisture in the soil and a 4.1 ton/acre yield increase with the use of IrrigAid Gold at 80 percent standard irrigation compared to 80 percent standard irrigation alone.
The surfactant also has been tested on potatoes in Wisconsin and Idaho and Pink Lady apples in Australia. One potato trial was conducted in 2004 by the University of Idaho. Treatments consisted of IrrigAid Gold and a control. The data was averaged over the five fields in the study that had less than optimum irrigation due to poor soil water-holding capacity and/or inadequate water availability. Both U.S. No. 1 and large-sized tubers showed highly significant increases with the soil surfactant treatment.
In 2006-07, David Bell, an independent researcher in Shepparton, Victoria, Australia conducted a trial with IrrigAid Gold (branded as AquaGro Gold in Australia) on Pink Lady apples in an area where water allocations were at 30 percent. This trial revealed that the application of the IrrigAid Gold chemistry over the summer months resulted in significant increase in the depth and content of moisture in the soils and increased fruit weight and yields. Trial work was continued in 2007-08 on Gala apples with similar results.
Florida grower gives it a shot
G&D Farms’ 380 acres of strawberries and 150 acres of vegetables often need irrigation to sustain plant growth and yield, so when Duane Kent, sales manager of Crop Protection Services of Florida Inc., Plant City, told G&D Farms’ supervisor Chris Parks about IrrigAid Gold, his interest was piqued.
“We get a lot of people who try to sell us stuff, but if you can see the results, it is worth using. I could see results with the first application within two hours,” Parks says.
The farm used IrrigAid Gold on its dry blocks of peppers this fall for the first time. “We had pretty good results. Our pepper was one of the most uniform crops we have had, especially on this soil. We farmed the same piece in the spring, and I could see a noticeable difference in the plant height and bush size this fall. We had a 4-inch taller bush. With a better bush, you get better quality,” Parks says.
Parks says the application was fairly simple. He pumped it into the drip irrigation. G&D Farms used 2 quarts per acre, waited three weeks and then used a quart per acre every two weeks. Parks says this rate was customized from the label with help from Dave Miller, Southeast territory manager for Aquatrols who came to the farm and tested moisture during the product’s use.
Parks says he could see the soil moisture spreading out across the bed more evenly. “You will never get the outer edges of your soil wet with drip. It drains over time,” he says. “But in two and a half hours, I could see the shoulders wet in spots that I would never have had wet before.”
Not only was the soil surfactant easy to apply and successful, it also was cost effective coming in at about $29 per acre, which Parks says is inexpensive compared with other products he has used in the past.
IrrigAid Gold also is efficient. Parks is using the soil surfactant on the company’s 180 acres of strawberries grown on sandy soil, and he says one bulk—or 260 gallons—will last until March.