136 THE SUGAR BEET. 



varies with the amount in the fertilizer.^ This chemi- 

 cal has but little influence upon the growth of the root. 

 In opposition to this Pagnoul advances the hypothesis 

 that its functions are as important as those of nitro- 

 gen, and, instead of preventing or diminishing the ab- 

 sorption of the nitrates by the beet, it facilitates it. 

 The basic phosphate of lime which is insoluble changes 

 and becomes soluble by combination with acids, and 

 consequently it is desirable to use the latter on soils 

 possessing these qualities, otherwise they will be 

 without effect. We now have the superphosphate 

 rendered soluble with sulphuric acid, it being thus pre- 

 pared in a commercial way before it is sold as a fer- 

 tilizer ; thus producing a double effect, furnishing the 

 phosphoric acid and also the lime. These penetrate 

 the subsoil and are then at the disposal of the roots. 

 They should not be used on acidulous soils which con- 

 tain about 11 per cent, of soluble acid. We now have 

 the precipitated phosphate, the use of which is not de- 

 sirable, as it is practically impossible to detect the 

 frauds that occur in selling it. If pure it contains as 

 much as 40 per cent, of phosphoric acid. Here also 

 they penetrate the subsoil. In consequence of the 

 damp condition in which these phosphates frequently 



' Experiments of Joulie: — 



Per cent, phosphoric acid 



in the root. 



Without phosphoric acid in the fertilizer . . . . 0.45 



.65'' " " "".... 0.55 



1.30" " " "".... 0.69 



1.92" " " "".... 1.11 



