FERTILIZERS. 



627 



The extent to which calcium carboiuite is dissolved in drainage water 

 of different soils is shown in the following table: 



Calcium carhonate in 1,000 cc. of drainage water. 



Grams. 

 Loam soil from "noiss and granite (containing 0.23 per cent CaO, trace CO5). 0.026 



Soil from Sihirian slate (3.32 per cent CaO, trace COj) 067 



Soil from Dyassic (Permian) sandstone (1.38 per cent CaO, 0.76 per cent CO-). . 052 



Soil from chalk sandstone (3.73 per cent CaO, 2.91 per cent CO.) 123 



Calcareons plain soil (11.31 per cent CaO, 8.12 per cent CO^) 1,51 



Hnmns soil (1.63 per cent CuO, 1.09 per cent COj) 065 



On the basis of these figures it is calculated that the amount of cal- 

 cium carbonate removed from a hectare of soil annually by the drain- 

 age water is oGl.G kg. This carbonate of lime has an important 

 influence on the circulation of fertilizing constituents in the soil. 

 Experiments showed that when Can2(C03)2, the form which appears 

 in the soil water, was mixed with an equivalent of monocalcium phos- 

 ])hate, CaH2(P()4)2, the tricalcium phosphate formed was not precipi- 

 tated, but was held in solution by the carbonic acid present. 



The amount of x)hosphoric acid appearing in the drainage water of 

 different kinds of soils is shown in the following table: 



I'hosphoric acid in drainage water of di(f'ereHt soils. 



The imiKH'tant fact to be obser\ ed in this table is that the humus 

 soil, which contained only 0.008 per cent of phosphoric acid soluble-in 

 hydrochloric acid, showed decidedly the highest loss of this substance 

 in the drainage. This in a measure confirms the generally accepted 

 view that such soils do not have a high retentive power for phosphates, 

 but readily convert insoluble into soluble forms, which are carried away 

 in the drainage. 



It is exi^lained that calcium sulphate is an invariable constituent of 

 superphosphates prepared by treatment of crude phosphate with sul- 

 phuric acid. The character and composition of the little balls formed 

 d^uring the preparation of superphosphates are described and illu.s- 

 13788— Ko. 7 i 



