Science: Soil Saver

Dr. Charles Allen Thomas, world-famed as a chemist but known to his neighbors as an amateur farmer, was annoyed by the farmland that he owned near Dayton, Ohio. Some parts of the same field yielded well, while other parts yielded badly. Chemical analysis showed that both patches had the same supply of plant nutrients. What was the difference?

Many other farmers had noted the same thing, and there were many theories. But Dr. Thomas, a research chemist who is now president of the great Monsanto Chemical Co., was in a position to spend time, money and talent on the problem. Last week at the Philadelphia meeting of the American Association for the Advancement of Science, a group of Monsanto chemists told about discoveries that are causing great excitement in agricultural circles. Monsanto may have found an answer to the world's eternal demand for more productive land.

Crumbs Needed. It is easy to add to a soil the chemicals that plants need, but every farmer knows that this is not enough. The soil must also have a good "structure," i.e., its particles must cling together in crumblike "aggregates." Without such crumbs, a soil containing much clay or silt will "slake" when wet, turning into sticky mud. Then as it dries, it develops a hard, dense crust that kills seedlings, resists tillage, and keeps needed water and air from penetrating the surface.

The traditional way to improve such soil is to add large amounts of manure or to plow under many crops of green stuff. When this organic material decays, a small part of it turns into natural gums called "polyuronides," which bind the soil particles together into the much-desired crumbs. But reforming a problem soil in this way is expensive and the polyuronides are quickly destroyed by soil bacteria.

The Monsanto chemists looked around for a chemical that would do the work of the polyuronides and also resist bacteria.

After following many false leads, they synthesized a material (which they named Krilium) that has an extraordinary effect on sticky clay soil.

Clinging Threads. When Krilium is mixed with sticky mud, its long threadlike molecules cling to the bits of clay, binding them strongly together. The mud turns into a mass of spongy crumbs. It takes very little Krilium to do the trick. In some cases, .02% is enough to turn a problem soil into a tractable one. One treatment lasts for at least 2½ years (the age of the oldest test plots), probably much longer.

A Krilium-treated soil, according to Monsanto, is easier to cultivate because it does not get sticky even when very wet. It holds more water than untreated soil, and so resists drought. No hard crust forms, and no clods; intractable clay or silt soil treated with Krilium behaves like a mellow loam full of organic matter.