134 



MAGNESIA IN OUR CULTIVATED CHOPS. 



a Farm-yard manure, 40 cubic yards, produced 12 tons 15 cwt. 

 Do. do., with 1^ cwt. sulphate of magnesia, ap- 

 plied as a top-dressing, . . . .13... 5... 



b Farm-yard manure, 36 cubic yards, . . 8 ... 17 ... 

 Do. do., and 2 cwt. sulphate of magnesia mixed 



with the manure, 11 ... 7 ... 



In both these cases, the results appear favourable; in the 

 latter decidedly so. At all events, they justify the institution 

 of new and more extended trials. 



On the whole, we may say that nothing very positive has 

 yet been ascertained as to the effect of sulphate of magnesia 

 upon our usually cultivated crops, when it is applied alone. 

 There are reasons for anticipating, however, that, in certain 

 circumstances, it should produce a favourable effect, especially 

 upon our grain crops. 



5. Proportion of magnesia contained in our usually cultivated 

 crops. Theory of the special action of sulphate of magnesia. 



1. Proportion of magnesia. The principal reason for the 

 anticipation stated at the close of the preceding section, is the 

 large proportion of magnesia which is present in the ash of 

 many of our cultivated, and especially of our grain crops. 

 This is exhibited in the following table : 



Proportion of magnesia in the ash of 



The seeds of our corn plants and of flax appear, from this 

 table, to contain more magnesia than beans or pease do, and much 

 more than is present in our root crops. In pulse and root crops, 

 lime generally exists in much larger proportion than magnesia. 



