DEPARTMENT OF AGRICULTURE, 



NEW SOUTH WALES. 



SCIENCE BULLETIN, No. 10. 



The Effect of Superphosphate on the 

 Wheat Yield in New South Wales. 



WALTER L. W4TERHOUSE, 

 Farrer Research Scholar, 1912. 



FOR some time it has been known that the manuring of wheat land with 

 superphosphate has met with varying results in different parts of New South 

 Wales. While in very many cases largely increased yields have been 

 obtained as a direct result, there are also instances in which no beneficial 

 effect has accrued, and others in which the fertiliser has apparently been 

 responsible for a diminished return. 



The manurial experiments carried out by the New South Wales Depart- 

 ment of Agriculture have already done much to throw light on the 

 problem. In the Agricultural Gazette of New South Wales, Vol. XXIII, 

 Part 5, is published an article on a Superphosphate for Wheat," in which 

 it is pointed out that an important principle for the guidance of farmers 

 in manuring wheat land is indicated by the results of manurial experi- 

 ments carried out in the years 1909, 1910, and 1911. " If these results are 

 maintained in succeeding years, it will be clear that the beneficial effect of 

 superphosphate decreases as we go north. On the south-western slopes and 

 in Riverina, the benefit derived from the application of about J cwt. of 

 superphosphate per acre is most marked. In the western districts, the 

 central portion of the wheat belt, there is still a considerable advantage, 

 but it is by no means as great as in the south. In the north-western 

 districts, the northern portion of the belt, the average yields indicate that 

 the benefit to be derived from superphosphate is not sufficient to cover the 

 cost of purchasing and applying the manure." 



These tentative conclusions are fully justified by the table of average 

 yields published and here reproduced in slightly modified form. 



TABLE I. Showing Average Yields in Manurial Trials, 1909-11, in Farmers' Whea 



Experiment Plots. 



42 Ib. Superphosphate peracre. 



