308 Agricultural Journal of Victoria. 



average of the results of these large numbers such irregularities, as 

 a rule, are got rid of, and features common to the soils of a particular 

 area or district — if there are such features, are brought into 

 prominence. It is the attempted discovery of such features common 

 to the soils of a district that constitutes the aim and the object of our 

 experimental manure tests. After this explanation we can now 

 examine the following table B, given on page 309, and see if the 

 various tests have disclosed a common deficiency, or a number of defi- 

 ciencies in Southern soils from the point of view of the requirements of 

 a potato crop. Although on the whole somewhat irregular, the returns 

 from the plots with the complete dressing show that the increased yields,, 

 taking the average of the 12 fields, are sufficient to result in very 

 large profits. With the medium dressing on plot 3, an increased 

 yield of 2"57 tons has been obtained as an average. Turning, how- 

 ever, to plot 12, where phosphoric acid only has been applied in the 

 shape of superphosphate, and not the three ingredients of a complete 

 manure, as in plot o, we find an increased yield of 2*17 tons. That 

 is, a yield nearly equalling that of plot 3, where nitrate of soda and 

 potash chloride, in addition to the same quantity of superphosphate^ 

 as used on plot 12, have been given. Without going into a detailed 

 criticism of the results of these experiments, it is evident that the 

 effects of a phosphatic manure on the potato crop have been most 

 pronounced. This is a feature common fo all the soils. The extra 

 vield shown on plot 3, with the complete manure over that of plot 12, 

 may be regarded as due to the combined effect of nitrogen and 

 potash. The effect, however, has been much less marked than with 

 the hay crops, and the conclusion may, I think, be drawn that, 

 generallv speaking, the addition of these two ingredients in anything- 

 but limited quantities will not be required in seasons similar to the 

 last except on the poorer soils, and even in their case great caution 

 must be used with respect to nitrate of soda, which has a tendency to 

 run the crop to top. These tests are not sufficiently numerous to 

 generalize too freely, but the results of the present year certainly 

 point to this direction. It is advisable in every way that the potato 

 grower should join the Department in a wide system of co-operative 

 experiments to test the manurial requirements of the soil generally in 

 the South with respect to the crop. 



