Why Midwest Growers Are Converting to Subsurface Drip Irrigation

Original Post by DTN / The Progressive Farmer (Emily Garnett)

Pivot irrigation is king in central Nebraska. Long, spindly arches stretch endlessly out across field after field, a visible reminder of the invisible — the vast and cherished Ogallala aquifer, buried hundreds of feet below Nebraska’s thirsty cornfields.

In Dawson County, however, a less visible irrigation system has been gaining traction with a few farmers. Since 2005, Lexington, Neb., farmer Don Anthony has been laying miles of small plastic tubing under his corn and soybean fields, until nearly one-fourth of his 1,200 acres are now solely watered by subsurface drip irrigation. His neighbor and best friend, Don Batie, has an 80-acre field in drip tape and hopes to add another 80 acres in the next five years.

They are oddities in this part of the country. “They think I’m crazy,” Anthony said of his neighbors, who primarily use center pivots and furrow irrigation to water the corn and soybeans that dominate this area. Subsurface drip irrigation has been around since the 1970s, but it has been mostly limited to smaller, more specialized fruit and vegetable operations. For the two Dons, however, drip irrigation has proven to be a flexible, water-saving addition to their irrigation systems.

BUCKING THE TREND

Just 200 miles east of Anthony and Batie’s farms, the first center pivots were manufactured by Robert Daugherty, the founder of Valmont Industries, who is credited with successfully commercializing the massive sprinkler systems. Today, such sprinkler systems account for 80% of Nebraska’s irrigated acres and more than 50% of the nation’s total irrigated acres.

As pervasive as pivots have become in large-scale row-crop operations, they do have some drawbacks. They are prone to wind and weather damage — Anthony credits a lightning strike with causing $40,000-plus in damage to one of his pivots four years ago. Their reach is limited in rectangular fields, and even corner arms — the costly additions that help center pivots reach field corners — leave some acres not watered. Their long, uniform arches make it difficult to set them up in odd-shaped fields, steep or uneven fields, or acres with obstacles such as creeks or power lines. And finally, despite excellent overall water efficiency, pivots can lose 10% to 25% of water they emit to evaporation and runoff, according to USDA studies.

Laying drip tape under their acres with creeks and power lines, steep hillsides and field corners have allowed Batie and Anthony to eek additional bushels out of their land with minimal water use. Drip irrigation systems can produce water efficiency rates as high as 95%, some studies show.

The Central Platte Natural Resource District that regulates water use in Dawson County, where Batie and Anthony farm, forbids landowners to convert any dryland to irrigation, and no new wells have been dug since 2006. In such regions, drip irrigation is at its most attractive, since any method that will save some water and add yields makes sense for these water-locked farmers, Anthony pointed out.

Last year, their area saw less than an inch of rain between May and harvest, Batie said. He applied between 18 and 25 inches of water on his pivot fields and 36 inches on his furrow irrigation fields. His 80 acres in the drip irrigation system, however, only needed 10 to 12 inches.

One 80-acre field of Anthony’s had been especially wasteful in the past. A power-line ran through the middle of it, forcing him to use furrow irrigation on it for years. The field’s soil, a heavy Hall-series silty clay, slowed the water running through it, and the far side of the field often burned up from lack of moisture, no matter how much water he applied. At the land’s driest, he soaked the field with 70 inches of water; even with a more water-efficient surge valve system, he could only cut it down to 40 inches. After burying drip tape under the problem field, Anthony said he averages only 8 to 10 inches of water on that field. In one exceptional year — in 2010 — he applied only 3.5 inches of water and grew 228-bushel corn.

… AND PAYING FOR IT

Both Batie and Anthony acknowledge the drip irrigation system has its drawbacks and is only worthwhile on certain acreages.

Depending on the field’s shape and size, costs of installing the system run from $1,200 to $2,300 an acre, double the cost of a traditional pivot system. Batie estimates it will take him six to 10 years to recover his 80-acre investment. The bigger the water savings, the faster the payback: Anthony estimated that paying back the problematic 80-acre field he converted from furrows to drip tape would take closer to five years.

Both Batie and Anthony have only installed drip tape on family-owned acres. With such a high initial investment, landowners are more wary. “The payout is so long, that I don’t know how you would do it with a landlord,” Anthony admitted.

While the tape may be safe from the effects of wind and weather, it does lie 16 inches underground, 60 inches apart, under a healthy stand of crops for part of the year, so maintenance involves getting your hands pretty dirty.

Also, Anthony and Batie have to filter their water before sending it through the drip tape. Both fight a constant battle with “clay-sand grit” that pervades their water supply and can clog the drip tape, which ranges in diameter from 5/8 of an inch to 1 and 1/8 inches. Anthony said adding a complex filter system called a “sand-media” filter upped his input costs by 12% in several fields where his tubes were clogging very quickly after the pump was turned on. Batie is now installing a remote monitoring system that will allow him to turn the water on and off, check on the pressure and flow of the water, and track his water use from a smartphone or computer.

Pressure gauges alert Batie and Anthony to clogs and leaks in the tape, and both have to do a fall “acid rinse” of the tape. Enfuric acid is mixed into their water tank until the water registers a PH of 2. The acidic water pumped through the drip tape burns away any deposits and has the added benefit of putting nitrogen into the soil and deterring rodents.

Although drip tape can be used to apply nitrogen, Batie and Anthony must spray foliar insecticides, fungicides, and other fertilizers separately. The tape also cannot help germinate seeds because it lies so far below the seedling. Fortunately, the no-till system that drip tape requires means the soil usually has enough moisture to put a stand up, Batie said. In his soybean fields, this very inability of weed seeds to germinate quickly after an initial post-planting spray has allowed him to cut his spraying passes from three to two.

WHILE THE GETTING’S GOOD

Both Batie and Anthony have plans to add more drip tape, but whether more neighbors will invest remains to be seen. “In this area, it’ll continue to go in, but you won’t see a land rush or anything,” Anthony predicted. Good farm incomes and high crop prices will be the driving factor, both men agreed.

“It’s hard when you’re scraping by to break even to make investments that have a 10-year or 15-year payback,” Anthony said. “It’s just a function of finances. But when you can put most of the money right down now, you’ll pay for it.”

Batie said farmers should take advantage of good farm incomes while they can. “High crop prices have made it a lot easier to do technological improvements, whether it’s pivots or drip tape or GPS technology,” he said. “Those are things we should have been doing years ago, but couldn’t. That’s why everyone’s doing it now, before this boom ends.”

To learn more about SDI, check out the “how-to” guide to subsurface drip irrigation.