Mechanized Plasticulture

On the scattered southwestern cotton fields, the slow, soft green of spring is sprouting against a strange background: glittering gridirons of broad black stripes. Paper-thin strips of polyethylene plastic stretch across the fields, warming the soil, conserving water, choking out weeds, protecting the land against the erosion of wind and rain. And if the coddled cotton crop that is even now poking tentatively into view grows close to its rich promise, its payoff may be the beginning of an agricultural revolution.

Help for Milquetoast. Polyethylene film has been used for years by truck farmers and up-to-the-minute home gardeners as a replacement for such traditional mulches as straw or sawdust. Spread on the ground in early spring, it has doubled the yield of tomatoes, squash or muskmelons. But as long as it had to be laid out by hand, it was far too expensive for such big-time crops as cotton. And cotton, which is one of the milquetoasts of the plant world, cries out for all the help it can get.

This year experimental farmers are conducting the first large-scale tryout of mechanized plasticulture. A tractor huffs across the field trailing a 20-in. band of black film from a big roll. Two disks cut furrows under the film's edges, rubber wheels press the edges down, and another pair of disks covers them with soil. Planting is done by hollow cone-shaped spikes that punch holes in the film 8 in. apart and insert slugs of moist vermiculite (puffed-up mica) that contain a cottonseed and carefully calculated doses of fertilizer, insecticide and fungicide. Snuggled in the warmth and moisture under the film, the seeds sprout quickly and grow up through the hole. Cotton plants mature as much as one month early. Weeds that grow in the bare soil between the strips of film can be easily destroyed without hurting the cotton.

After a plasticultured crop is picked, the film is gathered by a picturesque machine called a "desert stern-wheeler"--a great canted wheel studded with spikes, that picks up the used polyethylene for burning.

Flashy Stripes. To buy the film and use it costs $58 per acre, and savings in weed control average $12 per acre. At present prices for cotton, the grower would earn an extra $38 per acre by using film. Spencer Chemical Co. and Union Carbide, which manufacture the film and have developed the machines, are so certain that experience with plasticulture will bring even greater benefits that they are spending fortunes in research for the future. If this season's adventurous farmers from California to Texas harvest swollen crops, a good part of the 14,500,000 U.S. acres that are planted to cotton is almost certain to be flashily striped with polyethylene by next spring.

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