Paving the Way For More Food

For the agricultural scientist, the world's exploding population combines with its dwindling food supply to pose a twofold problem: how to increase the crop yield on existing farmland, and how to make use of acreage previously considered uncultivable. In the Philip pines, Rockefeller Foundation scientists have successfully tackled the first part of the problem by developing a short, stiff rice plant that may increase the average yield of each crop as much as 800%. Planted in test plots alongside the standard brand, the new rice rises in lush plants that make its old-fashioned cousin look like a victim of drought. Because it can also produce three crops a year instead of the usual one, it has the incredible potential of raising total output as much as 2,600% .

Taking an entirely different tack from the Rockefeller men, Michigan State University researchers have at tacked both parts of the food problem at once. Borrowing the methods and materials of highway builders, they have learned to lay down underground strips of asphalt that literally pave the way for richer crops of all varieties.

Agricultural Engineer Clarence Hansen and Agronomist A. Earl Erickson began working on the idea seven years ago when they noticed that certain areas of Michigan produced a high yield of crops from loose, sandy soil. The soil was productive, they realized, because an underlying layer of clay was trap ping rain water instead of allowing it to drain away, thus keeping the surface soil moist. "We decided to mimic these soils," says Erickson.

Easier decided than done. Neither artificial layers of clay nor sheets of polyethylene film placed two feet below the surface succeeded in retaining moisture. Rain water leaked through seams or holes, the soil dried out, and test crops fared badly. Then, at the suggestion of the American Oil Co., the researchers began experimenting with asphalt for their water barrier. Once they had perfected their technique, the results were immediate and bountiful.

Also for Paddyfields. Trial plantings of cabbage yielded 505 crates per acre of asphalt-layered soil, compared with 260 crates for untreated acres. Potato yields rose 50% and cucumbers as much as 100%. The economics were even more impressive. With cabbage selling at $2 per crate, the increased yield would bring a farmer added revenue of $490 per acre, allowing him to pay off the cost of the asphalt layer--about $225 per acre--with his first harvest. Furthermore, Hansen and Erickson estimate, the underground asphalt will not deteriorate for at least 15 years.

To achieve underground paving, the M.S.U. researchers designed a tractor-pulled Rube Goldberg device that lifts a 2-ft.-deep strip of earth from the field, sprays warm liquid asphalt underneath it, and then allows the soil to settle back in place. The asphalt solidifies immediately into a 34-in.-wide, 1/8-in.-thick ribbon. Adjacent ribbons are overlapped to ensure that the entire layer will be watertight. To reduce costs, Engineer Hansen is now working on a machine that will lay down lO-ft.-wide strips.

Asphalt barriers, say the M.S.U. men, can double the acreage of rice fields in the food-short countries of Southeast Asia. Used with the new Rockefeller Foundation strain of rice, they might free much of the world from the specter of famine.

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