SCIENCE BULLETIN, No. 9. 



Recent investigations have brought to light a host of other causes of infer- 

 tility, bu t the idea still persists at the back of many soil analyses, that the deter- 

 mination of the amount of certain specified plant-foods, dissolved by specific 

 solvents from the soil, is a certain guide to the nature of the manuring required. 

 As a matter of fact, neither tli3 chemical composition of the soil nor of the crop 

 affords any certain foundation on which advice as to manuring can be based. 



A. D. Hall and E. J. Russell,* dealing with the results of a soil survey of 

 the south-eastern counties of England, draw, amongst other general 

 conclusions, the following which have special reference to the connection 

 between the composition of the soil and plant: "We are not as yet in a 

 position to deduce the agricultural properties of a soil, either its behaviour 

 under cultivation or its adaptability to particular crops, except in the 

 roughest general fashion/'' 



In dealing with a number of typical wheat-soils the authors say, "chemical 

 analysis of these soils revealed rio connection between their chemical compo- 

 sition and their suitability for wheats," and the same remark applies no 

 doubt to other crops. They also point out that excess or deficiency of any 

 particular plant-food, such as nitrogen, does not necessarily imply a fertile or 

 infertile soil. 



Even in the case of calcium carbonate, they show that many soils poorly 

 supplied with this ingredient are not benefited by the application of lime, 

 whereas for other soils examined, containing the same or a greater proportion, 

 liming is essential. 



They find that, " other things being equal, dry soils are more likely to 

 respond to potassic manuring than others better supplied with water, but no 

 richer in available potash." 



The same applies to phosphoric acid. " Little, if any, direct connection 

 can be traced between the phosphoric acid and the productiveness." 



As far as regards the value of soil-analysis, as a ba&is on which to afford 

 advice as to soil treatment, I have no reason to alter the opinion expressed in 

 a paper on " Soil Analysis," read before this Association at the Brisbane 

 meeting, 1895, wherein the view is expressed that a rational scheme of soil- 

 analysis w r hich shall attempt rather to determine the factors influencing 

 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 subject, 

 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, sa}^ nitrogen and potash, but poor in phosphates, 

 it by no means follows with any certainty that it will be benefited by 

 phosphatic manuring. 



* Jmirn. Agric. Science, vol. 4, p. 182. 



