Small-scale irrigation offers alternative

Steve Guell would rather graze than feed more grain and hay

Waupun, Wisconsin—How much should a small-scale dairy grazier with limited acreage spend to ensure that his cows have full grazing through all those dry spells? If you have just 30 cows and maybe 40 or 50 acres of pasture, what would it be worth to keep that forage green and palatable straight through a long growing season — even in a region with enough rainfall to supposedly do the job?

How about $14,000?

That’s about what Steve Guell spent on his irrigation infrastructure over the past three years. The tab included $11,700 for a 275-foot well with 6-inch casing situated near the center of his dairy pasture, a 7.5-horsepower pump and associated equipment, plus about $5,000 for irrigation equipment, wiring and installation labor, minus a $2,900 rebate from his electric utility. Steve’s annual electric bill to run the system from 2006 through 2008 ranged from $150 to $424. Labor amounts to 15 minutes each day he moves the rig, which certainly isn’t every day during the grazing season.

For this investment, he’s able to fully graze 30 to 34 Jersey milk cows, plus dairy heifers and beef cows — a total of about 45 animal units — on 45 acres over an entire growing season, and do so without any commercial nitrogen. The milking herd consumes 6-8 lbs./cow of grain-based supplement and a pound or two of hay per day in producing a herd average of 11,000 lbs. of milk, 5.0-5.1% butterfat, and 3.6-3.7% protein. Daily feed costs on full pasture this spring were averaging $1.50 per cow, with 26 lbs. of pasture dry matter intake figured at 2 cents per pound.

Steve doesn’t know how much more pasture he’s growing with the irrigation. He does know that he no longer has to supplement with up to 10 lbs./cow/day of grain, protein and hay during extended summer droughts, as he often did before the irrigation was installed. He does know that his full-pasture ration is almost exactly half the cost of his winter confinement ration, even with pasture rent figured at $160/acre.

Steve figures the system has reduced hay and grain feeding by roughly 13 tons during the course of a seven-month grazing season without any noticeable effect upon milk and milk solids production.

When Steve was planning his system three years ago, he figured an adequate return on investment at a $100/ton cost for purchased and self-harvested feed. Now that feed costs have essentially doubled, he has no doubt.

“I’m very satisfied with the payback,” Steve says.

Pasture perennials need regular doses of water to perform, but this grazing situation doesn’t jump out as an obvious choice for irrigation. The water table is not high and surface water is not available. The farm’s silt-loam soils are not particularly droughty. This area of eastern Wisconsin historically averages around four inches of rainfall per month through the growing season, which is plenty if that’s what you actually get.

Which hasn’t always been the case, especially of late. Take last year. According to Steve’s detailed rainfall log, the farm received 15.95 inches of rain in June alone — almost four inches more than what fell over the rest of the growing season from mid-April through early October. August and September combined saw a total of five rainfall events providing just 3.6 inches. While 2008 was extreme, this wasn’t the first time that rainfall patterns were goofy enough to limit cool-season grass growth.

With limited pasture acreage, Steve was tired of supplementing with expensive feed as grass growth halted virtually every summer. He was fed up with seeing fall grazing compromised, and he was disappointed when he had to extend his rotations to save grass while watching milk production suffer because the pasture was overly mature.

“When I start grazing, I want to keep grazing,” he says.

Steve had read about lightweight pasture irrigation technology developed in New Zealand, and started talking with Roberts Irrigation, a Wisconsin firm that sells the K-line pod system. He also got in touch with his electric utility about the costs of drilling to deep water and pumping at enough pressure and volume to do the job. By early 2006, he had decided to go ahead with the project.

The $2,900 utility grant was applied to burying 500 feet of line from the pole to the well head. Steve signed up for the off-peak electric rate. Currently at 5 cents per kilowatt hour, this cost (between 8 p.m. and 8 a.m. weekdays, plus all day on weekends and holidays) compares to 17 cents for peak usage and 10 cents for the utility’s all-day program. (Electric rates have risen about 20% over the past three years.) Steve thus irrigates only at night, plus the occasional weekend during a severe drought.

He figures the well, with its six-inch casing, is more than just an irrigation investment. “It’s an asset that I can sell down the road,” Steve asserts.

Many individual feed and machinery repair bills are bigger than the price tag of the irrigation system itself. Initial cost for 600 feet of flexible plastic irrigation line (1.6-inch diameter) and 12 hard-plastic K-line sprinkler pods – capable of irrigating about 30 acres – was $1,200. Steve has since gained the ability to irrigate 20 more acres by spending $635 to add 600 feet of line from the well head to the pod line. He says two of the pods “disappeared” last year when the cows were accidentally allowed to walk through the system. Replacement cost: $31.

The pump was the biggest depreciable investment and the largest potential problem. Pressure at the furthest pod needs to be near 50 lbs./inch to achieve a full 50-foot diameter sprinkler circle capable of delivering just over a tenth of an inch of water per hour. With relatively little elevation change between the pasture’s lowest and highest points, pressure at the well head is set at 100 lbs.

So far, so good — in three years of usage, Steve has had no real problems with the pump and the system’s overall performance. The well and pump were sized to be capable of delivering enough water and pressure to handle a second pod system without compromising the performance of the first, although he has no intentions of adding on.

Steve hasn’t had a problem with the system’s labor requirements, either. When empty, the pod line is light enough to move by hand: Steve shifts it 50 feet in about 15 minutes. Interior fencing is entirely temporary polywire, so he doesn’t have to deal with fences while moving the system. Steve aims to irrigate an area of pasture within one week after the cattle have passed through. Every 10-14 days of use, he employs a tractor (a large ATV also works) to move the entire 1,200 feet of line.

That doesn’t mean he’s always moving every two weeks, because irrigation here is merely a supplement employed only when the grass really needs it, sometimes running for only a few nights at a time before being shut down. “I have it out there, and I can turn it on whenever I want to,” Steve explains. “I’m just trying to supplement natural rainfall to get up to the 4 inches per month average.”

He does admit to making one error that is common among inexperienced irrigators: “Probably every year I could start a week or two earlier.”

These systems can be adjusted to apply varying amounts of water. Steve’s 12 sprinklers are set to provide about an inch-and-a-half of water overnight to just over three-quarters of an acre, thus requiring at least 45 days to cover his entire pasture. The pump provides 50 gallons of water per minute.

That might not be good enough on sand or in an arid climate, but it works at Steve’s place, which has soils with decent water-holding capacity.

There are at least a couple of major advantages to irrigating in a humid climate: both evaporation losses and annual operating costs are lower compared to running a system in 100-degree desert heat. Steve’s electric bill is an obvious indicator of the season’s weather.

Last year, his charges at the dedicated electric pole were under $22 a month through the period covering most of August. But the farm received just 2 inches of rain and plenty of hot weather over a 60-day period starting August 5. The electric bill for the period from August 27 to September 27 came to $303 — almost three-quarters of the entire year’s cost.

But he grew a lot of high-quality grass last fall, and was able to do a lot more late-season grazing than would have been the case without the irrigation on his limited pasture base.

Steve now maintains a 30-day rotation through most of the grazing season, and he sees a marked improvement in forage quality and diversity. He estimates his stands are at 50% white clover (mainly Kopu II, seeded at 2 lbs./acre each spring with fertilizer) — about double the clover percentage he saw prior to irrigation. Orchardgrass and bluegrass are the primary grasses, although three or four others are always present.

“The grasses now have finer stems,” Steve relates. He applies some gypsum and trace elements every spring, and half the pasture gets compost each fall, but Steve doesn’t buy any commercial N despite shipping to a conventional market.

“I don’t want to crowd out the clovers,” he explains. “I’m looking for that higher-quality feed to keep the purchased feed bill down.”

Steve feels that such a strategy is going to be extremely important over the long run. “Even conventional feed is going to stay high,” he forecasts.