400 THE MUSTARD CROP. 



both the white and brown mustard just before harvest 

 time. This is the Uredo Candida, whose nature and 

 mode of attack are similar to those described at page 64 

 as injuring the wheat plant. 



The chemistry of the mustard crop has not been so 

 well worked out as that of our other fallow crops, the 

 chief attention having been paid to the seed produce, 

 whether used for grinding or for oil-pressing purposes. 



We know that, under favourable conditions of soil and 

 climate, a very large bulk of crop is obtained in a very 

 short time; and from the investigations of Dr. Voelcker 

 we are acquainted with the organic composition and con- 

 sequent feeding value, but we are without any very 

 correct knowledge of the inorganic or mineral constituents 

 which it requires for its growth, and which, from the 

 following analysis, it appears to contain in a very large 

 proportion : 



Composition of White Mustard (S. alba) in its fresh or natural state. 



Compounds containing nitrogen (albumen, &c.), 2'87 



Compounds not containing nitrogen, as gum, sugar, &c., 4'40 



vegetable fibre, 4'39 



Ash (inorganic or mineral matter), 2'04 



Water,... 86'30 



100-00 



If we compare this analysis with those of the foregoing 

 crops, we see that mustard contains a high proportion of 

 nutritive matter; this, combined with its rapid habit of 

 growth, fairly entitles it to more consideration at our 

 hands than it generally receives. Weight for weight, its 

 feeding powers considerably exceed those of the turnip; 

 while the large proportion of mineral matters which it 

 abstracts during its growth from the soil, explains the 

 cause why it has for so long a time been considered 

 valuable as a green manure for ploughing in, as a prepa- 

 ration for wheat and other of our cultivated crops. 



