By diving headfirst into a mammoth new irrigation program, Wendell Nicholas is improving his watering efficiency - one drip at a time.
Nicholas, who farms near Johnson, KS, is in the second stage of installing subsurface drip irrigation on his 10-section operation. Applied a half-section at a time with unique, specially built equipment, the project will eventually involve enough irrigation "tape" to stretch about 10,000 miles.
Nicholas grows irrigated corn, wheat and alfalfa. Most is still under furrow-surge irrigation. His surge system helps his watering efficiency, but not nearly enough to get the most from groundwater growing more scarce every year.
"We wanted to get better use of our water," he says. "We selected drip over center pivots. Initial costs are higher. But in the long run, we'll benefit from no runoff and no evaporation - and have the ability to water land that would be dryland corners in a circle pivot system."
The system features 13/8"-diameter, 15-mil-thick drip irrigation tape buried 16" deep in half-mile-long rows.
The rows are in 60" spacings. Water is applied from tape emitters spaced every 2". There are about 1,300 emitters on each line.
Tape is tied to a 1" tube. Tubes are clamped to outlets from an 8" submain line buried in a 42"-deep trench. The submain stretches one mile. The layout has eight separate zones along the half-section. Six zones have 132 outlets and two have 126.
Every other zone features a gear-up valve that carries water from a 12" main to the submain. The main is fed by a 1,600 gallon-per-minute well. A Flow-Guard filtration system keeps dirt and other materials from entering the tape.
The system waters corn planted in 30" rows.
"The 60" spacings provide plenty of water for the 30" rows," says Nicholas. "What I find amazing is that in 20 minutes or less we can have uniform emission on about 95% of the field."
Jim Whitesel, owner of a subsurface irrigation company in Miller, NE, helped coordinate installation. His company has installed drip systems for over 25 years. Most systems are installed a quarter-section at a time using chisel plows equipped with tubes to feed tape into the rows.
"Most of ours are three- or four-row chisels, but Wendell's is a six-row machine," says Whitesel.
"We wanted a tool that would help expedite installation," Nicholas explains. "We built a 30" implement with six 1" ripper shanks mounted on a Bigham Brothers toolbar."
Twelve spools, each with a half-mile of tape, are mounted on the toolbar. Tape is threaded through tubes on the shanks and spiked to the ground. The implement is pulled by a Case IH 9500 tractor. Once the half-mile of tape is laid, tape from the second spool is threaded for the return trip.
Nicholas is adding a second half-section of drip irrigation this winter. He plans to continue that trend in the coming years. Cost is about $500 per acre, compared to $250-400 per acre for a center-pivot system.
However, Nicholas believes the system will more than pay for itself in longevity. Whitesel adds that systems easily remain functional 20 years or more.
Nicholas' 175-bu corn yields were comparable to his normal yields last year, he says. A.D. Schneider, USDA-ARS ag engineer in Bushland and Amarillo, TX, says corn yields averaged 250 bu on a subsurface irrigation test field, 30% better than pivot and furrow systems. Soybean yields of 74-80 bu were also recorded, compared to 70 bu for traditional watering methods.
"We believe our biggest gains will be in irrigation efficiency," says Nicholas. "Our normal precipitation is 14". We grew our first corn crop under drip by applying about 16" of water (during an extremely dry, hot year). That can be lowered to 14" or less."
Whitesel says drip systems can regularly produce a corn crop using 20-30% less water than a low-pressure center-pivot system.