196 



Fertilisers 



[PT. Ill 



which usually contains about 5 per cent, of nitrogen, 

 2 per cent, of P2O5 {i.e., 4 per cent, of "phosphate") 

 and 1 per cent, of potash. 



Rape cake has long been used as a manure with good 

 results^ in this country and in India, and numerous ex- 

 periments at Rothamsted have proved its value both 

 on cereals and on roots (Table XV). There is nothing 

 to show, however, that it is worth a higher unit price 

 than the various guanos, and yet higher prices are not 

 uncommonly asked. 



Table XV. Effect of ra^ie cake on yields of barley 

 and mangolds, Rothamsted 



^ Rape cake alone: the addition of potash and phosphates has very 

 little further effect. 



2 Dung + potash and phosphates: this yield is, however, almost the 

 same as with dung alone. 



8 Rape cake + potash and phosphates, these being specially needed for 

 mangolds. 



* 18S5, 1901, and 1908 omitted. 



The effect only lasts for one year at Rothamsted and 

 no evidence has been obtained of any residual effect 

 (Table XVI). 



* An interesting old account is given by Hannam in Journ. Roy. Agric. 

 Soc, 1848, IV. 177. 



