PHOSPHATES AND SOIL ACIDITY.

Shannon News, 9 April 1925, Page 4

PHOSPHATES AND SOIL ACIDITY.

AN ERRONEOUS IDEA. The idea is still prevalent among many farmers that "phosphates" have the effect of making their soil acid or sour, in spite of the many explanations given by Agricultural Instructors and others. This idea was no doubt circulates in the first place by some interested parties, a semblance of truth being given on account of .the fact, that a strong acid—-sulphuric—• is used in its manufacture.

It is recognised to-day that this theory is entirely wrong. The only free acid in phosphate fertilisers, is "phosphoric" acid, an acid of which our soils, as a whole, are known to be deficient in. In fact, moisture and soluble phosphate may be regarded as the two most important factors in the growth of our crops and pastures. The presence of phosphoric acid in phosphates is in small quantities and will combine rapidly with lime, iron, etc. "Frete" sulphuric acid is never present in phosphates.

Phosphate manures are a mixture of several lime phosphates and gypsum and experiments conducted in many different soils in New Zealand and elsewhere have proved conclusively that they contain no more acid after using this fertiliser than before.