Water Dragons
From the ranch house porch, you can see the three giant pivoting sprinkler dragons that turn the bottomlands into huge green circles. Up close, they look like strange insects, thin pipes and wires, tires that roll along the ground, and at the end a big jet that looks like the head of a creature. The head goes cha cha cha as it shoots a rooster tail of water 40’, and all along the spine hang down smaller twirling sprinklers, swish swish. Every minute or so, the electric motor moves the whole thing another 6” with a soft whir,
The change in the landscape is tremendous. It was a dry, sagebrush flat, hot dusty and white to the eyes. Bound by a line of sandstone bluffs, the natural shape of the flats echoes the wanderings of the Bighorn River, but the green circles impose a radical and regular geometry. When the tractors cut the hay, they move in a perfect series of concentric circles too, and then later the balers follow, making giant clyndrical 1500 lb. bales. These get stacked in long rows.
I have always been fascinated by looking down from the air at the squares and rectangles of farmed fields, and how their geometry meets natural shapes of rivers or mountains or canyons. How close can the tractors go before the arroyo is too steep, or the river too deep ? I remember the first time I saw the circles from the air, I remember worrying about the corners of the old squares that now got no water, but also liking the interplay of shapes and colors of various crops and cycles.
If you don’t have a pivot, which costs a good $100,000, the work of irrigating is backbreaking labor, fields must be level, ditches dug and maintained, and monitored constantly. Gravity and muscles. Maybe pipes and sprinklers, but still an enormous amount of hard labor in the mud. When drought struck the heartland in the 1950’s, irrigating became mandatory, and Frank Zybach's first experimental center pivot system – built in 1947-8, soon became the only way to irrigate big acres. By 1973, there were 10,000 pivots in Nebraska alone, and the green circles were visible to the astronauts 270 miles in space.
Using water pressure to move at first, Zybach’s machine now runs on electricity, with rubber tires, and a computer system that controls the speed, the water amount ( less closer to the center where it moves slowly), even an extension arm that follows a buried wire and swings out to water those corners that worried me. There are now 4 manufacturers, all located in Nebraska. . The largest pivots use 10-inch diameter pipe and extend out 2,600 feet. So, the water in that system can weigh over 88,000 pounds, an under truss system and guy wires support the weight, especially important because it has to clear the tops of corn as high as an elephant’s eye.
The great beast can climb hills, and go down depressions. I can see the closest one ambling its way over the raised road that cuts through the field. The work of leveling a field to use gravity for irrigation isn’t needed.
The Pivots around here say Zimmatic on a sign hanging from their spine, for Paul Zimmerer of Lindsay NE, whose Lindsay Manufacturing introduced a knuckle joint that allowed his pivot to travel over even rougher terrain. Lindsay is the largest exporter of pivots, and second only to Valmont, the descendant of Zyback’s original company.
Green circles everywhere, even in the Sahara. Reliable crops even in the desert, even when the rain goes away. But all that water doesn’t always go back to the aquifer, and the cities in the desert use more and more water.
I have cleverly placed my tiny herb and tomato garden, in a big tractor tire, right at the edge of the pivot’s range, and until they make the second cutting, it gets watered by the dragon.
For more than you want to know about pivots: http://www.livinghistoryfarm.org/farminginthe50s/water_02.html