At this writing in autumn 2000, Tom has evaluated irrigation of only 41 acres and for only one year, but that happened to be during the severe drought of 2000. Being able to graze alfalfa during the drought and get 56-60 pounds of milk per cow convinced him to go ahead and expand the system.
Manure laden waste water from washing down the milking parlor twice a day flows into the lagoon (right photo). Currently the trench silo (photo below) located next to the lagoon is being used to hold well water. A suction hose connects the two reservoirs and allows mixing from the two sources through gate valves. For lower amounts of nutrients the gate valve for the lagoon would be opened three turns to six or nine turns for the well water in the trench silo. To increase the amount of nutrients, the lagoon valve would be opened more. A newly planted or a freshly grazed paddock would be watered with high levels of nutrients from the lagoon. During times of drought, the lagoon water would be diluted with a greater proportion of well water.
2,900 feet of three-inch PVC pipe carries water underground from the combined trench silo/waste lagoon source to eight hydrants located in the paddocks. Each hydrant waters two paddocks, so that 9 paddocks are not irrigated.
A 10 h.p. three-phase electric pump near the lagoon pumps water to the hydrants
The irrigaton system is built around a spider Tom observed in use on Irish dairy farms. Similar to the old-time two-arm lawn sprinkler, the back side of the spider is connected to the hydrant by 350 feet of hose. The front end of the spider is attached by cable to a post on the other side of the paddock. The force of the water turns the arms of the sprinkler, which ratchet the cable and pull the spider forward across the field, slinging water as it goes.
After observing the benefits of irrigation during a drought, Tom set out to make use of all the run-off he could capture, using advice from the Natural Resource Conservation Service as his guide. A new system is under construction that will collect all the run off from the pastures, rooflines and driveways into a 4.2 million-gallon pond reservoir located at the lowest point on the property. The reservoir will connect to existing underground lines and hydrants, so that the lagoon can still be used for supplying liquid fertilizer as needed. The initial investment of $10,700 paid for the pump, pipe, valves, hydrants and the water-propelled spider to irrigate 41 acres. The expanded system will cost $12,000 for the pond reservoir and $2,000 for additional pipe to cover all the paddocks. The total cost for irrigation will be $24,700.
This material is based upon work that is supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture through the Sustainable Agriculture Research and Education (SARE) program. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.