Overhead sprinkler technology has improved by “leaps and bounds” in recent years with improved system reliability, better drive systems to prevent mudding and much improved sprinkler packages to greatly improve irrigation uniformity and lessen runoff.
It would take pages to list the methods employed to get water to crops. Toward the bottom of that list would be an irrigation technology employed successfully worldwide yet conspicuously absent in significance for decades in the West — center pivot/lateral move mechanical-move irrigation.
There are probably 150,000 self-propelled irrigation systems on more than 20 million acres in the U.S. The number of center pivots increased by more than 50 percent from 1986 to 1996. The majority are to supplement rainfall. In the West there is nothing supplemental about irrigation.
Overhead mechanical systems in California date back to the water-driven steel wheel types. Modern era pivots and laterals have dotted the landscape, but lack of adaptability to the West’s style of farming soon relegate disassembled systems to the side of the fields headed for the metal recyclers. It has never been the dominant method of applying water as it is in places like Nebraska, Kansas and Iowa where from 35,000 feet it looks like endless green polka dots of pivots.
However, that is changing for a variety of reasons, according to Dan Munk, University of California Cooperative Extension irrigation/soils farm advisor for Fresno County, the No. 1 agricultural county in the nation.
One of the biggest drawbacks for years has been the fact that 28 to 30 acres of every 160-acre center pivot system had to be left unfarmed because of the inability to irrigate it with a circle.
“Not long ago those 28 acres were important. It is not on the radar with farmers as it once was because of the chronic shortage of water,” Munk says.
“Production is not so much about land anymore. It’s water,” says Munk. “We are already fallowing ground because of a lack of water.
“Farming is now a matter of survival in many areas of the West Side of the San Joaquin Valley. Only the highly efficient water users will survive and those are the growers getting on the train and going to drip systems or center pivots.”
In just the last couple of years, Munk estimates 25 new pivots have been installed in the Five Points area of Fresno County and another 30 systems in Western Madera County, in the heart of the West Side of the San Joaquin Valley.
“The lack of water is forcing growers who want to survive to drill wells to ensure a reliable water supply; not rely on surface deliveries and get center pivots going,” said Munk, acknowledging that this leads to questions of sustainability of groundwater supplies and the impact of high salts water on the mechanical metal systems as well as buildup in the soils.
However, those concerns give way to survival. Drip systems have been the No. 1 choice for most growers looking for maximum irrigation efficiency, but moving up fast are the center pivots.
One reason for that is improved system design technology and advanced nozzle technology.
“It is much easier today to match center pivot irrigation packages with soil types and water infiltration rates,” says Munk.
Farming with center pivots also requires a change of farming systems. Munk calls it a concentric system of farming verses farming on the flat and straight.
“It is an evolutionary issue when you move from hand lines or furrow/flood irrigation to pivots,” adds Munk.
The changes can be daunting, but for those who want to survive, they must be made, according to Munk.
Kern County on the southern end of the San Joaquin Valley has probably seen more overhead lateral and pivot systems installed than any other area of the Valley.
Aaron Blinn, Grimmway Farms irrigation equipment manager, disassembled more than a few and left them on the side of the field to be picked up.
However, systems continued to go in as growers continue to see new, more efficient, less labor intensive irrigation met. They are like a new double span Valmont system that has grown three crops of carrots on Grimmway’s land near Lamont, Calif.
It could be called the Cadillac of center pivots. Each span on the twin-span system is configured a little differently moving toward the edge. Using combinations of booms and drop nozzles, three distinct water patterns are produced according to Jon Johnston, of Irrigation Accessories Co., Vancouver, Wash., supplier of the booms and sprinklers.
“We have been pleased with the uniformity of the irrigation pattern. We are saving water and getting yields equal to hand lines,” said ranch manager Frankie Iturriria. Uniformity of water is the key in watering up seeded carrots for Grimmway, the world’s largest carrot producer. That is the reason for the unique sprinkler package on the Valmont pivot.
“The older pivots and laterals would not do the job this one will,” says Iturriria.
However, the primary reason for the new system is the rising cost of labor, according to Blinn and Iturriria.
“The cost and the availability of labor is the No. 1 reason we are using center pivots,” said Blinn. “It costs us 25 percent less in labor to get a stand with the pivot than with hand lines. There is a huge amount of labor in germinating a field of carrots with hand lines,” he says. “You literally have to have a solid set of sprinkler hand lines to germinate a seeded carrot field.”
Munk says growers in his area are also increasingly looking at labor costs. “Hand lines can be very efficient, but having to move them all the time is becoming a bigger issue.”
The new twin span Valmont system is on an organic field of carrots. “We do not have the luxury of an herbicide in organic carrots, which means we are constantly moving tractors and cultivators into the field. You have to constantly move hand lines to get equipment in a field. With a pivot, all you have to do is turn it on and move it away from where you need to do field work.”
The system is simple to operate, according to Iturriria. “I can power it up and turn it on from my office computer or my laptop. All I need to have someone do is turn on the water.”
Iturriria says what he saves in labor he offsets the loss of not farming the corners. However, Grimmway is not giving up the corners. There are blueberries in three of the four corners irrigated with above ground drip lines.
Center pivots and lateral move sprinklers are a big departure visually from other irrigation systems. They invite questions from neighbors.
“Growers ask mostly about labor savings and if these systems are easy or difficult to operate,” says the Grimmway ranch manager.
Jerry Gerdes, Valmont product manager, water application, admits the system at Grimmway is a bit overkill for a lower value crop like alfalfa. “However on hilly ground or where soils are heavier and it is difficult to get water into the ground, this package at Grimmway may be an answer.”
Mucking of tower wheels getting stuck are an issue, especially in the heavy clay soils often found in Central California. The Grimmway system has three tires per tower. They can be fitted with four and even rubber tracks for flotation as well as better traction.
One of the issues with older systems was that in the heat of summer, systems could not make a rotation quick enough to meet the crop’s water needs.
With systems like the one at Grimmway, it can make a rotation in five hours. With twin spans, Gerdes says no part of the field is without water for longer than 2.5 hours. With an adequate water supply and an up front design work to match flow rates, meeting crop needs in the summer becomes a non issue.
Water pressure and flow rates can be regulated to match crop water needs. This maximizes power efficiency.
The booms installed on the system at Grimmway greatly improved uniformity, according to Blinn. “The booms create a special sprinkler package that really makes this system work,” Gerdes says.
While the labor issue is the most significant factor in the installation of these systems, there are water savings, a growing concern for producers.
“There are opportunities to save some water,” says Munk.
Gerdes says it is difficult to quantify savings across the board, but he said a 10 percent to 30 percent water savings range is not unrealistic depending on the type of irrigation system a pivot or lateral would replace.
The remote control aspects of the system improve reliability. “You can dial up a machine from home and make sure everything is running right and not have to drive 50 miles to check it. If the machine goes down, you get a call that there is a problem.”
As the evolution continues from flood/furrow irrigation to center pivots and drip, cost becomes a factor. More than one farmer has described installing a pressurized system like drip “buying the farming all over again.”
A basic seven-span pivot costs $500 to $600 per acre. A twin span installation would be looking at about double that, which is roughly equal to a less expensive drip system.
Those are big numbers to swallow in today’s uncertain economy, but as Munk says, it can be a matter of survival.
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