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Cotton growers may be leaving money on the table if they wait too long to begin irrigating their crop, says Darrin Dodds, assistant Extension professor of plant and soil sciences at Mississippi State University. “A one week difference between initiating furrow irrigation can make a difference of 50 pounds in yield — at $1 to $1.50 cotton, that’s $50 to $75 per acre you’re potentially missing,” he said at the annual conference of the Mississippi Agricultural Consultants Association.
Capitalizing on cotton's horsepower
“We look at nodes above white flower as a measure of horsepower for producing cotton. If you go into bloom with 8 or 10 nodes above white flower, you know you’ve got a lot of horsepower in that plant and a lot of potential yield. If you delay irrigation until the first week of bloom, you’ve reduced the plant’s inherent horsepower and you’re potentially leaving yield on the table.”
A potential hangup with early irrigation initiation, Dodds says, is restriction of root growth that could cause yield loss. “But, in southeast Arkansas tests where irrigation was initiated one week prior to bloom, they saw no restriction of root growth.”
Irrigation also will increase plant height, he notes, “so you need to manage for that.”
Producers watering cotton with a center pivot system need to be particularly attuned to the crop’s water needs, Dodds says.
“With a pivot, you’re able to get only about half to one-third as much water to the crop as quickly as with furrow. And when it’s as hot and dry as it was in 2010, if you get behind with pivot irrigation, it’s awfully hard — sometimes impossible — to catch up to the crop’s need. It’s very important to protect deep moisture and to initiate irrigation prior to losing that moisture.”
The PHAUCET program for furrow irrigation, developed by Phil Tacker, former Arkansas Extension engineer, helps to determine the size of holes to punch in polypipe, calculates pressure changes along the length of the pipe, helps address different row lengths, calculates how many hours to pump in one set without problems, the length and slope of the pipe, row spacing, etc.
“Using this program can achieve water savings of as much as 25 percent,” Dodds says.
Variety selection is another important component of attaining maximum cotton production, he says.
“Growers have moved onto the technology highway en masse, and it’s obvious we’re going to continue to travel that road as companies put more genetic traits in their seed and more treatments on them.
“We’ve seen a lot of new varieties in the last two to three years — they’ve been coming more quickly than ever before. It has been somewhat of a challenge for those of us in the university community to get adequate data to put together for our growers and consultants, but we’re working closely with the seed companies to improve this situation.”