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Cotton Today

How is cotton harvested? Cotton grower Tiffany Shedd walks "Sonoran Living Live" through the process.

As one of Arizona’s Five Cs, cotton has helped shape our cities and our economic structure. At its peak of cultivation, about 800,000 acres of cotton grew on Arizona fields. Though cotton farming has decreased to about 200,000 acres today, yields per acre have increased and cotton remains an important part of Arizona agriculture. Pinal County is the largest producer in Arizona; Maricopa County is second.

About 900 cotton farms produce an average total of 600,000 bales (but yields vary every year) and supplied approximately $362 million in cash to the state economy in 2011. That’s enough cotton for at least one pair of jeans for every person in the United States.

Arizona is the birth place for Pima Cotton, a long-fiber variety (known as long staple cotton) named for the Pima Indians who helped cultivate it. A careful hybrid between Egyptian cotton and American strains, this crop was responsible for Arizona's cotton boom during World War I. Extra-long fibers make it both extremely durable and luxuriously soft, thus excellent for industrial and trade goods. Once bred for its durability, today, its brand, “Supima,” is popular with designers and high-end linen manufacturers.

In 1917, Goodyear Tire and Rubber Company bought land to cultivate long staple cotton for airplane tires, leading to the eventual founding of Goodyear, Arizona.

Pima cotton is still cultivated in Arizona, but most cotton farmers favor the short-staple variety known as Upland. Farmers here, like farmers everywhere, lead a precarious existence due to the volatility of the crop and of the market. The past few years have been good for cotton growers, with prices hovering near $2 per pound—the highest since the Civil War. The state’s 900 cotton farms, many of them family owned and operated, are enjoying the boom but planning for potential changes.  

Cultivation and Water Use

Cotton boll ready for harvest.

Many farmers utilize no-till farming, a method practiced by American Indian tribes of the southwest since crop cultivation began. Instead of breaking up the soil by burying last year’s crop under the earth, no till soil begins with bare dirt and plows deep furrows in rows where seeds will be planted. Because this method leads to higher water infiltration and nutrient storage capacity, amount of water and organic matter (fertilizer) in the soil are naturally increase, and less needs to be used. Less tillage also reduces labor and machinery use, and decreases erosion.

A cotton crop needs about 2.5 acre-feet of water per acre. Application efficiency is paramount, as every drop is precious. Drip irrigation systems supply water to some fields, and the sprinklers are precisely placed and monitored to supply water at critical times. In furrow irrigation, excess water runs off into a catchment ditch to be picked up by neighboring farmers, or reused from the catchment ditch through a pump-back system.The Arid Land Research Center is constantly searching for new ways to evolve irrigation technology.

No matter what method is used, farmers must still find creative solutions for weeds, pests, disease, and other common problems. To help recycle the cotton plant, the University of Arizona developed the Stalk Puller System as a method of harvesting the cotton stalks as a biomass fuel feedstock.

Fighting Pests... with Pests?

Randy Ryan of the Agricultural Experiment Station at the University of Arizona explains the benefits of genetic engineering to Arizona’s cotton crop.

Many insects love to eat cotton plants. Historically, farmers have battled these pests, and the devastation of their crop, by spraying insecticides. Cotton is one of the most heavily sprayed crops, but too much pesticide can pollute fields and water sources. The industry is always on its toes in an attempt to stay one step ahead of pests like the boll weevil and the pink worm. One breakthrough came when some cotton seeds were genetically modified to include Bt, a natural insecticide. This cotton actually kills boll weevils trying to feed on it, so farmers spray less.

Arizona farmers have developed another weapon in their pest-control arsenal: a moth factory. This enterprise targets the pink bollworm, a moth that lays its eggs in cotton buds and produces tiny striped worms that eat their way through the crop. To fight this persistent pest, agricultural specialists are taking drastic action. They are making more of them.

A 69,000 square foot warehouse located in the vicinity of Sky Harbor Airport churns out 22 million adult pink bollworm moths per day. But there is something special about these moths. A few minutes in a radiation chamber has taken away their ability to reproduce. Of course, the moths don’t know that. When they are released on area cotton farms, they mate with naturally born adults. However, no babies are produced by these moths. The next generation of moths remains at a manageable size, ensuring the next generation of cotton.