TKANSACTIONS OF SECTION B. 



557 



As Top Dressitiff. 



No. 



Description of manure 



Quantity of 

 manure per acre 



Produce in 

 tons per acre 



Nothino: but dung . 

 I Sulphate of magnesia 

 { Sulphate of soda . 

 I Nitrate of soda 

 j /Nitrate of soda 

 I \^ Sulphate of magnesia 



40 c. yards 



11 cwt. 



2 „ 

 li 



■i- 3 » 

 1 „ 



1 „ 



Manure mixed with dung at time of planting. 



Farmyard dung alone 

 Sulphate of magnesia 

 Sulphate of soda . 



35 c. yards. 

 2 cwt. 



12-75 

 13-25 

 12-75 

 IGO 



22-5 



8-75 



11-35 



8-00 



These results are very interesting. It might be supposed that the increase in the' 

 crop -was due to the sulphuric acid, and not to the magnesia ; hut, inasmuch as 

 sidphate of soda gave no advantage, the effect is plainly not due to the sidphuric 

 acid, unless we suppose the soda to have been injurious, which is not likely to have 

 been the case. An increase of sulphate of magnesia appears also to improve the 

 crop. When 1^ cwt. of the salt was used, as a top dressing, with the diuig, the 

 increase was only 4 per cent. ; but when 2 cwt. was used with the dung, at the 

 time of planting, the increase was close upon 80 per cent. The result of this ex- 

 periment appears, moreover, to confirm the view that the mixture of the ashes of 

 sea-weed and dung derives no unimportant advantage from the quantity of magnesia 

 thus introduced into the plant. 



4. On Clover and Rye Grass cut for hay by Mr. McLean, Braidwood, Mid- 

 lothian, 1842. 



Nothing . . . gave 



Sulphate of magnesia, 1^ cwt. „ 

 Gypsum, 3 cwt. . . . „ 



Here the use of li cwt. of sidphate of magnesia gave the enormous increase of 

 upwards of 130 per cent., whilst 3 cwt. of gypsum (sulphate of lime) gave an. 

 increase of 60 per cent. only. It will be of interest at this pomt to refer to the 

 composition of the mineral constituents of the tvu-nip, potato, clover, and hay, as 

 respects the proportions in them of lime and magnesia, for we shall then see that 

 the advantage gained by the crops experimented on has been m general accordance 

 with what might have been expected from the components of their ashes. I have 

 given also the percentage of sulphuric acid for reasons stated below. 



125 stones per acre. 



290 



200 



and 5-55 per cent, of magnesia, and clover and rye-grass crops (taken in the average 

 proportion of tlie ashes of their respective crops, viz. 400 lbs. to 220 lbs. per acre,) 



