What's it worth to keep grass growing?
Yoders use irrigation ponds to take the edge off summer droughts.
Spencer, Wisconsin - Each spring, Aaron Yoder watched the melt water and early-spring rains flowing over the frozen ground, down the modest slope and off his farm. Then, by mid-summer most years, the pastures would turn brown as the rains stayed away for weeks on end.
North-Central Wisconsin's dairy belt is supposed to feature a near-perfect climate for summer forage growth. But in this decade, with moderate to severe drought descending almost every year, the situation was becoming frustrating and expensive enough to cause some serious thinking.
"I knew what grass could do if it had water," Aaron said. "If we could just somehow catch this water and use it when we needed it…"
Turns out he could. Last winter, Aaron spent about $4,000 to have a half-acre pond dug through silt and clay to a maximum depth of about 11 feet. Costs were kept reasonable by the fact that this was the swampy site of an old pond that had long ago silted up. Also helping was the fact that local environmental officials did not object to the project.
Aaron admits to having "no clue" as to how well this would work when he made up his mind to do the digging. All he knew was that he was tired of not being able to fully graze the dairy herd through the summer, and that he had no desire to spend more than $10,000 on a deep well employed solely for irrigation.
"I also hated the idea of pulling the cold water from deep underground," he said.
Though the drainage basin is barely 40 acres, and the great majority of that land is in sod, the pond filled to the brim last spring. Aaron was ready to go when the rains stopped coming in early summer, with a six horsepower gasoline-powered pump motor, 1,000 feet of 3-inch feeder line, a 10-pod K-Line irrigation line, and hundreds of thousands of gallons of pond water in reserve. On July 3 he started irrigating a day or two behind the cows in rotation, applying an inch of water to just over half an acre of pasture every eight hours or so.
Though he started before the soil surface was completely dry, subsurface reserves had been tapped by previous years' dry weather. So Aaron upped the applications to near 1.5 inches on just over an acre each day. With the motor's three-quarter-gallon fuel tank providing just four hours of running time, he had to keep on top of the action. He'd refill the tank at 10 p.m., and again at 5 a.m. Aaron shifted the pod line twice daily - by hand for the smaller moves, with a lawnmower for the longer ones. He connected the 150-foot long feeder line and pod line to risers positioned in the center of his five-acre paddocks.
"I knew that as long as I could keep that grass from going dormant, I had a chance to feed my cows," he explains.
It worked. By watering six days a week over a six-week period with almost no rain, he was able to keep 20 of his 30 dairy pasture acres green, growing and full of clover. The 45 Holsteins and crossbreds grazed days on the irrigated ground, nights on the dry land pastures. Milk production in the organic-certified herd held at 45-50 lbs./cow through the cool, droughty mid-summer on pasture, a couple of pounds of dry hay, and just 4 lbs./day of small grains.
The heavens finally opened, and Aaron stopped irrigating August 10. In slightly moister conditions the previous year he had been out of pasture by the first of August. In 2008 the grass had gone dormant and never fully responded to any rains that came later, so Aaron fed a lot of stored forage in late summer and fall.
This year, an estimated 2.5 to 3 inches of irrigation water per acre kept his cows fully fed on quality pasture for six weeks until the rains came. This forage growth came at the expense of the amortized cost of the pond and $4,500 worth of irrigation equipment, less than $300 of gasoline for the pump, and Aaron's labor to move equipment and fill the tank.
By keeping his cows on pasture, Aaron is pretty sure he avoided buying at least one $5,000 load of organic hay, and milk production almost certainly was better with the availability of high-quality pasture.
"So it looks like I paid for the pond in one year," he says.
Aaron also put his forages in a position for a growth explosion when the rains returned, as the acreage watered through the drought responded far better to the August rain compared to the area that had been allowed to go dormant.
The pond, which dropped to a little less than half full in early August, had nearly recharged itself by early September with the help of several inches of rain and a couple of small springs. And the forage silo was still capped.
Down the road a mile or two, Aaron's brother, Kenneth, was doing pretty much the same thing this year. His pond is about the same depth, but closer to a full acre on the surface. At about $15,000, his was a more expensive project because of the size and the fact that a small grove of trees was removed. The drainage area feeding this pond is bigger, too. Kenneth figures some of the cost can be allocated to recreational use, since his children swim in the new pond.
Kenneth used a pair of K-Line systems, each with six pods, to apply 1.5 inches of water per 24 hours, irrigating a total of 15 acres through the drought. He attached a 15-gallon auxiliary tank to the same kind of pump Aaron used, and thus refilled every 24 hours. His gasoline cost , also came to about $300 for six weeks of pumping.
He was impressed by the pasture growth throughout the summer - especially with the surge in clover production. Kenneth figures he grew an extra dry-matter ton/acre of organic-certified forage with the irrigation.
"I should have done this a few years earlier," he says.
Back at his place, Aaron is thinking seriously about expanding the irrigation system. "I could have put more water onlast summer," he explains. "Now that I know what the pond will do, I'm thinking of doing more."
The pump was run at less than full throttle, and Aaron figures he had another 20 days of water left in the pond. He'll do some calculating to see how much more volume the current pump can handle, but is almost certain to purchase another K-Line system. He recently buried the main supply line, and he could easily extend it for access to the dairy pasture that was dry this year. Aaron also intends to add an auxiliary gas tank like his brother's to eliminate the frequent refills.
And on the other side of his farmstead there happens to be a low, wet place that collects water from an area at least aslarge as the one that feeds the current pond. If this part of North-Central Wisconsin stays dry, Aaron figures it might pay someday to double his ability to irrigate.
by Joel McNair
Reprinted from Graze magazine Volume 16, No.9 November 2009