SMALL MINERAL LOSS

Bay of Plenty Beacon, Volume 11, Issue 51, 9 July 1947, Page 8

SMALL MINERAL LOSS

UNUSUAL “BALANCE SHEET” A national mineral balance sheet has been prepared by Dr. E. B. Davies, agricultural chemist at the Soil Fertility Research Station, Hamilton. It shows the quantity of the three main elements, phosphate, potash and calcium leaving the country by way of our farming exports, the amount lost in sewage, and on the credit side, the amount imported as fertiliser.

With the exception of potash there is an overwhelming surplus on the credit side.

' Dr. Davies has calculated that 5120 tons of phosphate are sent overseas in our primary exports, and 1800 tons are lost in sewage, but 120,000 tons come into the country yearly in the form of phosphatic fertilisers. No item has been overlooked on the debit side—even the 160 tons of phosphate in our wool exports, and the 30 tons in the condensed milk. A similar set of figures applies for calcium, with the difference that this mineral is replenished from local deposits of limestone. While we are exporting more potash than is feeing returned to the soil, Dr. Davies explains that imports of this fertiliser are much below the pre-war level. In 1939 the two items balanced.

His conclusion is that the loss of soil minerals by the way of sewage and exports is not of great consequence. But the important loss which must be replaced is that which occurs through normal leaching by soil drainage.