372 Journal of the Department of Agriculture. 



place readily when solutions of these two coiuijounds are added one to 

 the other, but this reaction would take place very slowly in the soil, 

 and that only when the sulphate of lime is present in a large excess. 



It should also be pointed out that in the case of some of the 

 Provinces no data were available for calculating the unit values of 

 some of the fertilizing constituents. For instance, in the case of the 

 Cape Province, no trustworthy information could be obtained as to 

 the probable unit value of the nitrogen in blood and meat meals. In 

 such a case as this, the unit value obtained from data in one of the 

 other Provinces (in this particular instance Natal) is given in tlio 

 subjoined lists: — 



1 .—-Nitrogen . 



^1 , ., , Unif Values for 



Natal. (Jape. li'ansvaal. 



s. d. s. d. s. d. 



(1) jN'itric nitrogen in nitrate of soda ... 81 -i :'^1 3 31 3 



(2) Ammoniacal nitrogen in sulphate of 



ammonia 34 (1 34 34 (i 



('{) Organic nitrogen in blood and meat 



meals 25 6 25 f) 25 3. 



(4) Organic nitrogen in dissolved bones... 25 G 25 fi 25 3, 



(5) Organic nitrogen in raw bone products 20 20 20 



2. — PJiospliorir O.ridc. 



(1) Water-.soluble phosphoric oxide in 



superphosphate 14 :'. 21 19 



(2) Water-soluble pbosplioric oxide in dis- 



solved bones 15 20 !) 20 



(3) Citric-solulile pliosplioric oxide in 



basic slag 14 3 14 3 14 3, 



(4) Citric-soluble phosphoric oxide in 



bone products, etc 8 (> 9 9 



(5) Insoluble phosphoric oxide 4 3 4 (i 4 



?>.— Potash. 



(1) As carbonate 7 7 7 



(2) As chloride 10 (i 10 G 10 (i 



(3) As sulphate ; 14 14 14 



Note. — In case of a fertilizer where figures are given lor water- 

 soluble, citric-soluble, and total phosphoric oxide the insoluble phos- 

 phoric oxide is the difference between the total and citric-soluble 

 phosphoric oxide. Again, in valuing such a fertilizer it is only to 

 that portion of the citric-soluble phosphoric oxide not included in the 

 water-soluble part that the unit value for citric-soluble applies. For 

 example, if a superphosphate contains 14 per cent, water-soluble, 

 16 per cent, citric-soluble, and 17 per cent, total phosphoric oxide, it 

 will be necessary first to calculate the value of the 14 per cent, water- 

 soluble phosphoric oxide, then the value of the remaining 2 per 

 cent, citric-soluble, and, lastly, the 1 per cent. iusolu})le phosphoric 

 oxide. 



