NEW LIGHT ON PROBLEMS OF SOIL FERTILITY

Bay of Plenty Beacon, Volume 14, Issue 9, 8 July 1949, Page 5

NEW LIGHT ON PROBLEMS OF SOIL FERTILITY

Never before has farming been so full of faddists making loud claims and crying simple cures. In the latest issue of the authoritative Scientific Monthly, Dr Charles E. Kellogg, head of the Division of Soil Survey, U.S. Department of Agriculture, assesses them all with a sceptical eye. Some of the popular theories, he believes, have good things in them, but none of them tell the whole story. The oldest of the fashionable farming theories, says Dr Kellogg, teaches that “the soil is like a bank;” the farmer must deposit (in fer-i tiliser) as much as he take out (in crops), or eventually overdraw his account. This is true only in certain areas, says Dr Kellogg. Many soils can be cropped indefinitely without loss of fertility. The chemical elements taken away by crops are restored by silt, dust and volcanic ash. Other chemicals work their way up from below. Dr Kellogg does not believe that fertilisers are unnecessary, but he thinks that farmers who follow the “bank” theory often waste money by applying “complete” fertlisers that their soils do not need.

Erosion is another menace that Dr Kellogg thinks has been oversold. Some soils erose badly, he says, but others do not, even on steep, long-cultivated slopes. Great gullies cutting through a field destroy its value, but gradual erosion does little harm and may even be beneficial. When the topsoil washes gradually away, the subsoil may turn into topsoli with renewed fertility. “Much (erosion),” says Dr Kellogg, “is a perfectly normal concomitant of mountain building and wearing down . . . An important part is essential to the formation of productive soils. One cannot, or should not, try to stop erosion, but rather to control it.”