644: PROCEEDINGS OF SECTION K 



(Report Australian Association Advancement Science, vol. VI,. 

 p. 288). The view is therein expressed that a rational scheme 

 o^ soil-analysis which shall attempt rather to determine the 

 factors influencing soil-fertility than to elaborate methods for 

 determining the chemical constitution of the soil can be made 

 of considerable value to the farmer. This statement has been 

 amply borne out by experience, and to-day the analysis of farmers' 

 Soils on the lines then laid down is one of the functions of the 

 Department most regularly availed of by farmers. 



In spite of all the labour expended for many years on this sub- 

 ject, manuring still remains very largely empirical in its nature. 

 We know in a broad and general way that a soil deficient in plant- 

 food is not likely to produce good crops without manuring, and 

 that a soil rich in plant-food is likely to prove a fertile one. But 

 much further than this we cannot go. If a soil is well supplied 

 with, say, nitrogen and potash, but poor in phosphates, it by no 

 means follows with any certainty that it will be benefited by phos- 

 phatic manuring. We know further that certain fertilizers benefit 

 certain crops. We know, for example, that the application of 

 superphosphate will probably increase the yield of wheat and other 

 cereals; but this knowledge is not derived from information sup- 

 plied by the composition either of the soil or the wheat plant. 



The wheat-crop, grain and straw, contains only haH the quan- 

 tity of phosphoric acid that it does of nitrogen, and much less than 

 it does of potash, and yet we know that neither nitrogenous nor 

 potash manures are anything like as effective as soluble prosphates 

 in increasing the yield. Nor does soil-analysis help us to any ex- 

 tent. The soil may be comparatively rich in phosphates, and poor 

 in nitrogen and potash, and still phosphatic manuring is the more 

 effective. Our wheat soils in the semi-dry country are indeed lack- 

 ing, for the most part, in humus and nitrogen, and yet it is by the 

 application of superphosphates, and not of nitrogenous manures, 

 that crops are successfully grown. 



The case of leguminous plants is of a similar nature ; crops like 

 peas and beans and clover contain more nitrogen than other 

 fertilizing ingredients, and yet manuring with nitrogen is 

 resultless, and the ingredients which are most beneficial are potash 

 and phosphates. Here again, it is immaterial whether the soil is 

 rich or poor in nitrogen or rich in potash. "The composition of 

 fruit trees does not explain why potash manuring should be of such 

 special benefit, nor is there any satisfactory explanation why the 

 mangel-crop, which contains nearly four times the amount of 

 potash as does the potato-crop, should not benefit by the applica- 

 tion of this ingredient, whereas it is an essential " dominant " in- 

 gredient for manures applied to potatoes. 



