33 



constituent. Approximately equal proportions of potash and nitrogen 

 depending on soil analysis go to make up the other half of a complete 

 fertilizer. 



It is during the present war, and it is feared will be for some 

 time to come afterwards, impossible to secure the once ordinary 

 chemical fertilizers to which reference has been made. 



Under the circumstances, resort must be had to those substances 

 which are obtainable within South Africa. 



Taking phosphatic manures first, one finds the principal supply 

 must be derived fr«m bone meal. It is time, and efforts are being 

 made, to open up other sources from wliich to obtain phosphates of 

 some kind or other, but the results of these are not yet apparent. 



Superphosphate. 



Lime. 



Basis Slag and 

 Calcium Cyanamide. 



Potash Salts, 



Kainit. 



Nitrate of Soda. 



Bone meal, however, is an excellent source of supply, and should 

 answer all our requirements if a sufficient quantity is obtainable. 

 Analysis of locally ground bone meal gives the following : — 



Nitrogen 6.216 



Phosphoric oxide 11.26 



Phosphoric oxide (soluble) 6.91 



Such an article should be supplied from the abattoirs of any of 

 our large towns at a moderate price. 



Potash is to be found on the Karroo in the form of " burnt kraal 

 manure." This is obtained by burning out the old sheep and goat 

 kraals which have been present in varioiis parts of that country for 

 ages. The result is a most useful ash which contains 10-12 per cent, 

 potash, besides lime, there is no nitrogen present. Unfortunately 

 the supply is far from being inexhaustible, and, further, the approach- 

 ing scarcity is attracting the attention of speculators, who buy up 

 whole kraals, grind the ash up fine, perhaps add a little sand, and 

 then sell the material by weight. One should therefore be careful 

 from whom this kraal ash is purchased. 



Nitrogen is obtainable from dried blood — also the product of the 

 abattoirs — and this usually contains about 12 per cent, nitrogen. Its 

 use is not advocated to any considerable extent, and certainly not as 

 a source of regular supply of this very important element of plant- 

 food. An occasional application in moderate quantities is, however, 

 frequently of great benefit. Bone meal also contains a certain amount 



