CH. XI] Oil Cakes 19b 



it is liable to variations in composition and physical con- 

 dition: it should only be bought after analysis and at 

 prices less per unit than meat or fish guano. 



Dried blood. This usually contains about ] 2 per cent, 

 of nitrogen though occasional samples rise nearly to 

 15 per cent, and it decomposes so rapidly that it com- 

 mands a specially high price, and indeed is usually too 

 costly about 12 per ton before the war for ordinary 

 purposes. It is, however, used in high class horticultural 

 work, e.g., for roses, carnations, vines, etc., and much 

 of it is bought for America and for the better grade of 

 mixed and patent fertilisers. 



Hoofs and horns. Good samples of these contain 12 to 

 14 per cent, of nitrogen. When finely divided they are 

 very effective for glasshouse work, and competition for 

 the supply has sent up prices considerably ; hoofs are 

 supposed to be better than horns. Another grade 

 admixed with bone is also obtainable containing about 

 10 per cent, of nitrogen and 20-25 per cent, of phosphate. 

 "Dust to |-inch" is a favourite grist; coarser samples 

 are of little use, and the rough material called scutch, 

 sometimes offered for farm use and consisting of hair, 

 hoof and bone, should only be applied after it has been 

 well broken up, 



(B) Vegetable Origin 

 Oil cakes 



The large demand for oils and fats has created an 

 enormous industry in pressing out oil from oil seeds. 

 In some cases e.g., linseed and cotton the residues 

 have considerable value as cattle food: in other cases 

 they are unsuitable for this purpose and are then offered 

 as manure. The best known in this country is rape cake, 



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