PART II. AGRICULTURAL CHEMICAL METHODS. 



It was assumed, without argument, on a previous page, that the chemi- 

 cal analysis of soils had some value. Just what that value is, and on what 

 conditions it depends*, may to a limited extent be discussed later; but it 

 may here be convenient to allude to the fact that there are those who 

 would deny that it possesses any practical utility whatever. Thus Wal- 

 lace* remarks : 



" No analyst, using the ordinary processes for soil analysis, can determine whether or 

 not such infinitesimal amounts as are required by the crops are presenti or are not present 

 in an available form in the soil." 



Professor Whitney f again observes : 



" It appears, further, that practically all soils contain sufficient plant-food for good 

 crop yield ; that this supply will be indefinitely maintained, and that this actual yield of 

 plants adapted to the soil depends mainly, under favourable climatic conditions, upon the 

 cultural methods and suitable crop rotation ...... and that a chemical analysis 



of a soil, even by these extremely delicate and sensitive methods, will in itself give no 

 indication of the fertility of this soil or of the probable yield of a crop, and it seems 

 probable that this can only be determined, if at all, by physical methods, as it lies in the 

 domain of soil physics." 



On the other hand, Professor Hilgard has the following : 



" Whitney (Bull. 22, U.S. Bureau of Soils) claims, on the basis of a large number of 

 (three minute) extractions of soils made with distilled water, that these solutions are 

 essentially of the same composition in all soils ; that all soils contain enough plant-food to 

 produce crops indefinitely, and that the differences in production are due wholly to 

 differences in the moisture supply which he claims is, aside from climate, the only govern- 

 ing factor in plant growth. The tables of analytical results given in Bull. 22 fail to 

 sustain the first contention ; the second is pointedly contradicted both by practical 

 experience and by thousands of cumulative culture experiments made by scientific observers; 

 the third fails with the second, except, of course, in so far as an adequate supply of moisture 

 is known to be an absolute condition both of plant growth and the utilization of plant- 

 food. It is, moreover, well known that it is not water alone, but water impregnated more 

 or less with humic and carbonic acids, that is the active solvent surrounding the plant 

 -root." 



Granting that the chemico-agricultural analysis of soils is not an ab- 

 solute but a relative method of estimating their fertility a point that 

 will be reverted to later it will at o-nce be seen that such a survey of 

 this Colony's soils as was proposed necessitated the adoption of uniform, 

 or, at least, of comparable methods of procedure throughout. In order, 

 furthermore, to' enable comparisons to be drawn between our results and 

 those obtained in other parts of the world, or with those arrived at by 

 other analysts in this country, it becomes requisite fully to describe the 

 actual mode of procedure adopted. From the first it was realised that the 

 investigations would extend over many years, even without the unfoire- 

 seen interruptions which were subsequently caused by war and financial 

 depression. It was practically certain also that, with the advance of 

 scientific knowledge, there would be improvements in manipulation during 

 the course of the survey, and it was therefore recognised as most desir- 

 able to adopt stated methods at the o<utset, and to adhere to them in all 

 essentials throughout the whole series, a course without which results 

 could not be strictly comparable amongst themselves. The great obstacle 

 in the way of this was the fundamental differences which exist between 

 agricultural methods of operation in this country and those practised in 

 the northern hemisphere, where alone opportunity has hitherto offered of 

 comparing laboratory results with field experiments. To do this as it 

 really needed to be done would have involved years of preliminary work; 

 not to do it might waste years in the employment of unsuitable analyti- 



* "Rural Economy and Agriculture of Australia and New Zealand." p. 169. 



"The Chemistry of the Soil as related to crop production," 1903, p. 64. 

 $ " Soils : Their formation, properties, composition, and relations to climate and 

 plant growth," 1906, pp. 321, 322. 



