Irrigation management and capital expenditures affect net income 
By James D. Ritchie

Water-at-will can be good drought insurance, but it comes at a higher premium these days. Irrigation costs took a big jump last summer due to higher energy prices and—in some cases—greater pumping lift requirements as groundwater levels declined.

And the fuel price hike may not be over yet. A national outlook projects crude oil prices to average above $63 per barrel through 2006, which would push diesel, propane and natural gas prices higher. So far, higher fuel prices have not resulted in as big increases in electricity costs, which may be up 2 to 3 percent from 2005 to 2006.

That scenario has irrigators scrambling to trim costs, improve efficiency or both. Some are looking at ways to change or modify their existing irrigation system, but Gary Hoette, University of Missouri  extension agronomist at Montgomery City, cautions that change usually comes at a cost.

"The only reason to make a big change in an irrigation system is to wind up with more net dollars," he said. "Higher fuel costs alone won't justify too big a fixed cost in equipment or modifications."

"Hours of use per season is a critical factor," said Joe Henggeler, MU irrigation specialist. "In most of the Midwest, we use irrigation to supplement rainfall, which means we typically run irrigation pumps only 500 to 600 hours per season. Any capital expenditure for equipment or modifications gets spread over fewer hours than with an irrigation system in, say, the High Plains."

Before undertaking a major modification, an irrigator should first examine the efficiency of the pumping plant itself. Often, substantial savings in fuel cost can be gained by improving pumping plant performance and water use management with an existing system.

"Irrigation is a system of crop production and should be viewed that way," said Hoette. "One change can bring about several other changes. For example, in this area, we have poor water-holding soils and a poor water infiltration rate. We get along best when we can put on relatively small amounts of water more often.

"But you don't just start squirting water on the field," he added. "Irrigation requires taking into account plant populations, fertility management and a host of other considerations. Our soils are subject to ponding when too much water is applied, which affects soil-oxygen levels and nitrogen availability and can stress plants. A weakened plant is more susceptible to disease and insect damage."

Relatively low-capital system modifications can be made that improve water application efficiency and lower operating costs.

Low-pressure nozzles

Most conventional center pivots can be retrofitted with low-pressure nozzles on drop tubes.

"Low-pressure systems take less pumping power," said Hoette. "They cost less to operate; I'd go with the lowest pressure system that would do the job."

A low-pressure system may result in better water application efficiency, too. But there are several up-front costs that need to be considered. In addition to modifying the distribution system, you may need to adjust the existing pump (or pumps) by adjusting the bowl to allow for the drop in pressure. This adjustment can create inefficiencies in the pump and wipe out some of the cost savings. The greater the depth from which water is pumped, the more the inefficiency in the pumping plant.

Get an urge to surge

Adding surge valves to an existing furrow-flood system can improve water use efficiency, especially on sand and other light soils. A surge valve directs water to one section of the field, and then switches to another section, and back again. By alternating the water from one section of the field to the other, soils are allowed to "seal" so that the next surge of water doesn't drain through the same area of topsoil. In this way, a surge valve increases application efficiency by reducing tailwater volume and deep percolation. The general rule is that the greater the improvement in application efficiency, the quicker a surge valve will pay for itself.

From furrow to pivot

Whether it's profitable to switch from an existing furrow-flood system to a center pivot depends on several things. Costs include the pivot and sprinklers, underground pipes from the well to the center pivot, and possible replacement of the pump. Some of this investment may be offset by the salvage value of gated pipe, but the net investment to install a new low-pressure center pivot and modify the pump will run $35,000 or higher for a quarter-section rig. Per-acre fuel costs aren't likely to be any lower and may be considerably higher with a pivot compared with a furrow-flood system. Labor costs should be lower.

What power source?

If you are installing a new irrigation system, or making major modifications to an existing one, what kind of pumping power will you pick? The relationship of fixed and operating costs among diesel, propane and electricity can vary by area, and from time to time, as prices of different sources of energy change.

"All systems are subject to failure at some point: pipes burst, engines fail, motors burn out," said Gary Hoette. "It's important to have a system that can be kept on line through the irrigation season."

Diesel is the first choice of many irrigating producers, although it's more expensive than some systems to install and to operate. But diesel power is flexible and more farmers are familiar with diesel. Also, diesel service and repairs are more widely available.

Pumping units powered by propane or natural gas are not as widely used as diesel in the mid-continent. Engines of equivalent size usually cost about the same, whether fueled by propane or diesel, although propane is a slightly cheaper fuel in some areas. Natural gas availability depends on your proximity to a natural gas pipeline.

"If I were putting in a new system right now, I'd opt for electricity," said Joe Henggeler. "Electricity is the cheapest per unit of power and is cheaper to install, just for the equipment itself. It's also simpler to automate. It doesn't take very sophisticated controls to shut down an internal-combustion engine. But it's difficult to automate re-starting. With electricity, automating both stopping and starting is relatively easy."

Electrical pumping units may be less costly to install and operate, but getting power can be pricey.

"We operate on a case-by-case basis, with a line deposit system," said Mike Fuller, with Consolidated Electric Cooperative, Mexico, Mo. "As the member uses power, we refund part of the deposit. With irrigation, it may take several years to refund the full amount, because irrigation is a very seasonal use."

Generally, to set transformers and extend three-phase power, Consolidated requires a deposit of $31,000 per mile of line. Single-phase power requires a deposit of $27,000 per mile of line extension.

"As the member uses power, we refund on the first 1,000 feet of line extension," said Fuller. "We build our system to handle peak capacities, but we may need to make a peak demand charge, because irrigation season coincides with peak demand for air conditioning and other uses. However, we can juggle meter reading dates so that peak demand charges begin when irrigation actually begins, and many irrigators run more than one center pivot off the same meter."

"If you're irrigating only sporadically, say up to 500 hours a year or so, you may want to look at using a tractor and PTO-driven irrigation pump," suggests Henggeler. "That can lower fixed costs, compared with buying an engine or motor earmarked solely for irrigation."