7- ] oiirnal of Agriculture .Victoria. [lo Feb.. ipii- 



(2) That phosphoric acid is singularly deficient, both in totat 



amount and in the percentage readily soluble in weak acids. 

 Generally speaicing, there is not the same difference in the 

 amounts present in the surface soib and the subsoil as is 

 found in typical soils in Europe and America. The average 

 total amount is about .06 per cent. 



(3) That potash is generally present in fairly large amounts, com- 



pared with the phosphoric acid, except on the recent alluvial 

 soils near the sea coast. The amount present shows much' 

 greater variations than is the case with the nitrogen and 

 phosphoric acid. Its average amount varies from .2 to- 

 .4 per cent., and even up to i per cent. 



The results of the analyses of '702 samples of soil show that in 350 

 cases the amount of phosphoric acid is less than .05 per cent. ; in 214 

 cases between .05 per cent, and .1 per cent. ; in 74 between .1 and .15 

 per cent., and in 64 cases over .15 per cent. The area of the State, 

 corresponding to soils exhibiting these various quantities of phosphoric 

 acid, is not, however, proportional to the above numbers. 



We have been working chiefly on the poorer .soils, and, consequently, 

 the number of analy.ses, with the percentage of pho.-,phoric acid below 

 .05 per cent., is correspondingly great. These poor soils are found chiefly 

 in a number of areas of sandy lanci along the coast, and in the poorer 

 portions of the Mallee. The greater part of Victoria is covered with 

 surface soil running from .05 to .15 per cent, of phosphoric acid, while 

 the volcanic and alluvial soils often attain percentages exceeding .15 

 per cent. 



Although the amount of work done in this direction is not great enough 

 to allow of wide generalizations, there is no doubt that the tendency is, 

 with advancing civilization, for the difference between the surface soil 

 and the subsoil to become more and more marked. This differentiation 

 is due in the first place to the plant, and subsequently to the animal, but 

 when plants and animals are directed and controlled by human agency, 

 the process of differentiation proceeds at a much greater rate. I have 

 already frequently pointed out that the roots of plants in foraging for 

 phosphoric acid along with the other plant foods throughout considerable 

 volumes of both surface and subsoil, bring about a process of concentra- 

 tion of phosphoric acid in their tissues. This phosphoric acid is chiefly 

 found, first of all. in the growing parts of the plant, and, at a subsequent 

 period, in the seed and its neighbourhood. Purely supporting tissues, 

 such as the straw of ripened grain, and the wood of forest trees, contain 

 very small percentages. The animal appropriates the phosphoric acid' 

 from the plant, requiring it to build up all its tissues. Finally, the 

 phosphoric acid is, for the most part, concentrated in the bones. 



How the animal acts as an additional factor, in concentrating phos- 

 phoric acid, is in this way : Every time a plant is browsed off a f resh^ 

 attempt is made to .secure sufiicient nutriment to produce flower and seed. 

 The consequence is that plants which are browsed upon by herbivorous 

 animals are compelled to bring up much larger quantities of phosphoric 

 acid to the surface than those which are allowed to accomplish their life 

 cycle undisturbed. The animal thus compels the plant to bring up more 

 phosphoric acid, and then concentrates the phosphates chiefly in the 

 bones. When decay occurs the bones are slowly but surely incorporated 

 in the earth. During the life of the animal a certain amount of phos- 

 phates are kept in continual circulation through being returned to the- 



