As far as his cotton irrigation application rate is concerned, “less is more” for Johnny Lindley.
He's saving water without sacrificing yields. And he's not afraid to swap out center pivot drop nozzles to improve efficiency on one field or apply fertilizer on another.
Lindley farms cotton and wheat on the Red River bottom near Memphis, TX. His cotton operation features five center pivots, including one new half-mile rig that will help him convert more dryland acres.
With 60" drop tube spacings on his 30"-row cotton, he runs ultra-efficient LEPA (low energy precision application) hoses on some fields. Other pivots are equipped with low-pressure spray nozzles, which can be used for both irrigation and chemigation.
“We have always had good irrigation water (sources), but some wells are starting to weaken,” says Lindley. “So we make sure we use watering systems that are as beneficial as possible for our land.”
Many argue that LEPA is the way to go on flat land or if water is limited. There is virtually a 98% efficiency rating. Runoff is nil, especially if growers use furrow dikes. Lindley does when he uses the LEPA hoses, which drag on the surfaces between rows.
The 1" hoses are used on Lindley's flat land. But on fields that lie on more rolling hills, the low-pressure spray nozzles work more efficiently because there is less chance for runoff.
To reduce runoff, he also cuts back on application rates. “Some have recommended that you set your pivots to put down 1.2" of water per week,” he says. “But I found that there were often puddles on the surface at that rate. So I slightly increased the speed of the pivot, which decreased the application rate to 0.8 to 0.9.”
The results are yields in the 2½-bale range, similar to what he yielded at the 1.2" application rate.
Lindley hopes to begin applying his yellow herbicide through chemigation with the convertible spray nozzles. “Right now, we apply about 75% of our nitrogen through the pivot,” he says. “We will add proper mixing tanks to enable us to apply our herbicide.”
Like Lindley, other growers must account for field slope when choosing their irrigation systems. Whether you grow corn, cotton, soybeans, or all three, water efficiency holds input costs down.
Kansas State University Ag Engineer Danny Rogers says if the slope exceeds 1%, consider the application's spray. Runoff losses can top 30% with the LEPA bubble nozzle, even if furrow dikes are used.
“In fully irrigated corn, we saw a 50-bu yield advantage for the flat spray over the LEPA bubble mode,” says Rogers. “I have no problem recommending LEPA to growers who have fields under that 1% slope and have low irrigation capacity. But over that could cost them water and yields.”