Rotation to a West Texas farmer means occasionally changing cotton varieties, according to Dan Krieg, long time Texas Tech University crop physiology professor.
It's the only rotation that makes sense where rainfall and irrigation water can be as scarce as a gaggle of geese in Wink, Texas.
Krieg was part of a panel discussing the role of crop rotation in cotton production at the recent Beltwide Cotton Conferences in San Antonio, Texas.
Nearly 5 million acres of cotton are grown annually in the world's largest cotton patch, West Texas, where average rainfall ranges from a respectable 26 inches on the east side of the Rolling Plains to 16 inches on the west side of the High Plains.
Effective summer rainfall in the High Plains over the past half dozen years has averaged 15 inches from mid-April to October. Last season and 2002 even 15 inches would have seemed like Christmas in July.
“2003 was the second driest annual precipitation on record since 1911, only 8.3 inches,” said Krieg. “Some of you in this room get that much in one day.”
A huge ocean of water, the Ogallala Aquifer underlies West Texas, but it is deep, expensive to pump and diminishing, according to Krieg.
Regardless of whether the water is from wells or dribbles ever so miserly from the sky, cotton remains the best crop economically for West Texas farmers.
Krieg said cotton returns $35 to $40 per inch of water; corn $30 to $32; sorghum $16 to $18; wheat $10 to $12.
Peanuts top the list at $45 to $50, but potential is limited by water availability and high production costs, said Krieg.
Dryland cotton offers the greatest probability of giving a farmer a harvestable crop on both the High Plains (80 percent) and Rolling Plains (90 percent) than any other crop.
“Gross income and yield definitely favor cotton,” Krieg said.
One area where farmers follow a rotation system with a crop other than cotton is on lands in the Southern High Plains designed as highly erodible land (HEL). There growers must have a high residue crop on a certain percentage of their land to participate in the federal farm program.
This area's dryland cotton is largely planted in a 2×1 skip-row pattern, said Krieg.
A grower can use 33 percent of the land area in the blank row for grain sorghum and get both agronomic and economic benefits and still be eligible for the farm program.
This concept has been evaluated for a decade. The solid-planted cotton-sorghum system produced 90 percent of the cotton yield compared to continuous skip-row cotton.
“The bottom-line for the cotton-sorghum system was just slightly greater than the continuous skip-row cotton system,” said Krieg. The only real benefit was complying with HEL requirements and getting farm program benefits.
About 50 percent of the High Plains's cotton is irrigated. Dryland cotton is predominant in the Rolling Plains.
Where irrigation water is available, Krieg said continuous cotton, grown with modern, highly efficient water application systems uses the limited resource with the greatest efficiency. It is the most profitable production system available, he said.