Irrigation addition = $500/acre payoff

That particular field was bright green due to a 1,200-foot-long center pivot he had installed the year before. From mid-June to the last of August 2009, that pivot logged approximately 448 hours of operation, sometimes applying 3∕4 inch each time around, although most circles were set at 3∕10 inch to reduce water runoff.

When that cropping year ended, Armistead's surrounding dryland cornfields averaged only 113 bushels per acre. By comparison, the irrigated land went for an average of 264 bushels.

Not only that, but a test sample located inside the pivot circle was selected for a National Corn Growers Association (NCGA) contest entry, bringing in 305.9 bushels. That broke the existing Kentucky yield record.

Armistead was sold on irrigation. He pocketed a net profit from that irrigated field of over $68,000 in 2009. That's after deducting all production expenses and the annual cost of the 10-year lease of the center pivot.

More records and another pivot

Since that time, Armistead has won the state NCGA competition four more times in two different categories: irrigated and no-till/strip-till irrigated. In the meantime, he has also installed a second pivot. This time, it was a towable unit moved between two fields.

Using a towable

This past year, that towable sprinkler started out "on corn, where it covers 48 acres," he explains. "Then, after the corn is well along, I'll move it to a field where it will cover 55 acres of no-till double-cropped soybeans behind wheat. It could cover more in the first field, but I have to turn off the end gun and reverse it when it comes to a power line. Consequently, it can't make a full circle in the lower field.

"So far, I've just been using a straight rate of seed and fertilizer under the pivots, while using variable rates everywhere else," he says. "But I think this next year, I'm going to start variable-rating under the pivots. There are a few sweet spots within the circles where I believe it will pay."

$500 return vs. dryland acres

Even without variable-rate seeding, Armistead says he has been able to profit up to $500 or more per acre from irrigated fields compared to dryland acres. He has been able to save the $10 to $12 per acre that it costs for an aerial application by applying insecticide and fungicide through his pivot system.

Armistead has used the pivots to apply liquid nitrogen. By spoon-feeding the crop through the pivot, he has already brought the total nitrogen application in the circle to less than 1 pound per bushel harvested.

Irrigation pioneer

Armistead's success has made him an irrigation pioneer in his area of the Mid-South. When he first started with irrigation, much of the knowledge he gleaned about its operation was based on magazine articles that reported on watering in Western states.

"The best idea I used was employing moisture sensors in the ground to provide some suggestion of when I needed to irrigate and if I was applying enough water," he says.

Another idea he picked up has been crucial in helping other farmers in his area adapt to sprinkler irrigation. Since the area's main source of water is from surface water, Armistead employs a screening device that prevented silt and vegetative trash from entering the sprinkler system.