610 Journal of Agriculture, Victoria. [10 Oct., 1918. 



THE RESIDUAL EFFECT OF SUPERPHOSPHATE. 



By George 8. Gordon, Field Officer, Werrihee Research Farm. 



It is generally recognised tliat tlie soil over the greater portion of 

 Victoria is more or less deficient in those natural phosphates which are 

 required if maximum yields are to be obtained. In some districts, when 

 the first few crops have further depleted the virgin soil of this element, 

 profitable crops can no longer be grown without the use of farm-yard 

 manure or artificial fertilizers — generally superphosphate. On the aver- 

 age farm the quantity of manure available, and the labour necessary for 

 distributing it, are limited, while the smaller quantity required per acre, 

 easy distribution by means of the grain and fertilizer drill, together 

 with the handsome profit earned on the outlay, has in the past few years 

 caused a great increase in the demand for such fertilizers as super- 

 phosphate, Thomas' phosphate, basic phosphate, bonedust, &c., all of 

 which contain the essential plant food — phosphorus — in different forms. 



The following figures from the Victorian Year-Booh for 1913-14 

 show a gradual increase in the use of artificial fertilizers from 1901 to 

 1913:— 



" The area on which manure was used represented only 7 per cent, 

 of that under crop in 1898," comments the Government Statist; "but 

 since then the proportion manured has rapidly increased. In 1901 it 

 was 19 per cent.; in 1903, 36 per cent.; in 1904, 46 per cent.; in 1905, 

 56 per cent.; in 1909, 66 per cent.; in 1911 and 1912, 74 per cent.; and 

 in 1913, 77 per cent. During 1913 the quantity of manure imported 

 into Victoria from oversea countries was 87,536 tons, and its value 

 £231,757. Seventy-seven per cent, of the quantity, representing 74 per 

 cent, of the value, consisted of rock phosphates imported from Ocean 

 Island.'' 



It is sometimes said that little progress is being made here in agricul- 

 tural practice, but the rapid increase in the demand for superphosphate 

 proves that in this branch, at least, an advance has been made. Besides 

 being of direct advantage to the farmer, the manufacture of superphos- 



