Furrow and pivot systems get the same pre-plant fertility as drip, but furrow-irrigated fields don’t get in-season nitrogen applications. “We inject nitrogen through the pivot and drip systems. We’ve used pretty much the same thing for the past six years, but we’re looking at soil samples, accompanied by petiole testing to determine how much to inject. We want to see if we can save a little on fertilizer.”

He’s also considering variable rate application technology to further refine his fertility program. “I’m working with Helena to knife in fertilizer, using a Veris Rig as a base for pre-plant fertility. I want to do more with variable rate application; I’m just getting started.”

He uses some aerial imagery to improve efficiency of plant growth regulatorsand harvest aids with variable rate aerial applications. “Then we’ll add yield monitors and field maps to identify soils that need more fertilizer.”

Seidenberger uses global positioning technology to install drip irrigation systems, too. “All my drip tape except the first 45 acres was installedwith the RTK system. We still use that system when we work that field, but we have to adjust for it.”

He uses ECO Drip for subsurface drip irrigation materials and Netafim tape and filters.

He relies on GPS for more than just installing drip tape. “If the RTK goes down while I’m planting a drip-irrigated field, I shut down. We have to be exactly on the row when we pick six rows at a time.  It also helps to water precisely when you are right on the tapes.”

Some of Seidenberger’s tape is spaced 80 inches between rows and some is on 40-inch spacing under the row.

“If I were doing it all over, I’d put it all 40 inches under the row. That spacing takes about half as much water and gets moisture to the top easier. I could farm flat with the narrow spaces. But the 40-inch tape spacing is quite a bit more expensive to install because there is more drip tape in the fields.”

Pre-watering to plant on 40-inch spacings takes as little as 4 inches of water, Seidenberger says. With 80-inch spaces, he may need 10 inches of pre-watering in a dry year to get the beds wet on both sides of the tape.

Most of his wells supply from 2 to 3 gallons per minute per acre. “Three gallons provides 15/100 inch per day for the crop. During peak moisture demand — blooming — cotton uses 3/10 inch a day. So during blooming, we are only giving the plant half of the water itneeds every dayWe just hope we keep enough moisture in the soil profile to get us through or get a rain.”

He says 5 to 6 gallons per minute per acre is “ideal for drip irrigation to provide cotton all the water it needs through the season. We’re always behind — sometimes rain catches us up, but in-season we run the system all the time to stay where we need to be. Some farmers are using 1.5 to 2 gallons per minute per acre and still making good yields.”

His 2010 crop was a little off from 2009, Seidenberger says; it was hurt by a too-wet June and earlyJuly and a too-dry August. Still, with a combination of good yields and excellent price, he expects a good cotton year. And he’ll soon be busy getting ready to make his next crop.