ACIDITY OF THE SOIL.

King Country Chronicle, Volume XXIX, Issue 4694, 16 May 1935, Page 7

ACIDITY OF THE SOIL.

NOT INCREASED BY SUPERPHOSPHATE.

Many agriculturists still wrongly hold the opinion that continued liberal dressings of superphosphate develop an acid condition of the soil. Analytical investigations in the leading agricultural countries of the world have definitely established the fact that this is not the case, and experiments have shown that superphosphate neither causes acidity nor increases the acidity which may exist in the soil; actually, the Americans were the first to disprove the contention that superphosphate acidified soil.

“Well made superphosphate has no acidifying effect on soils,” states Sir John Russell, director of the Rothamsted Agricultural Experimental Station in England. At this celebrated institution, which was founded in 1843, and which has since enjoyed a worldwide reputation for its fertiliser experiments, close attention has been given for many years to the subject of acidity of the soil, and in 1856 an experiment field was commenced. Since then the field has been manured solely with superphosphate dressings of 439 kilos per hectare (equal to approximately 3921 b per acre) given annually. In 1925 its degree of acidity had undergone no change whatever,, although it had received over a total period of 76 years 32 tons of superphosphate per hectare (equal to about 13 tons per.acre). In 1927 the Rothamsted Station undertook a complete series of new experiments with a view to checking these results, and, for this purpose, a certain number of soils, coming from different districts were studied very closely. At the same time field experiments were carried on in sev-

eral countries. Increased dressings of superphosphate, varying between 800 and 1600 kilos per hectare (between 713.76 and 1427.521 b per acre) were given. In no case did any increase of acidity occur, and it was even found that, in the case of the two most acid soils, the acidity had actually diminished materially.