EXPERIMENTS ON WHEAT AND BARLEY. 175 



These experiments are favourable to the employment of 

 both nitrates as top-dressings, when laid on to the extent of 1 J 

 cwt. per acre, though more favourable to the action of the nitrate 

 of soda. One circumstance in favour of this latter nitrate is its 

 greater solubility, and its tendency to deliquesce in moist air. 

 This enables it to assume or to retain the fluid form in states of 

 the air, which may be too dry to allow the nitrate of potash to 

 diffuse itself through the soil and be taken up by the plant. In 

 the average of cases, therefore, we are entitled to expect a more 

 distinct effect from the nitrate of soda than from saltpetre, unless 

 it be shown by comparative experiments that it is on the special 

 action of the potash or the soda, and not on that of the nitric 

 acid common to both, that their beneficial action in this or that 

 circumstance of soil or crop mainly depends. In the first and 

 third of the above experiments, the application of common salt 

 on a third portion of each of the same fields diminished the crop, 

 in the second it increased the grain by 150 lb., but diminished 

 the produce of straw. It is possible, therefore, that, in this 

 second case, some of the good done by the nitrate of soda was due 

 to the soda it contained and supplied to the soil and to the crop. 



2. Experiments on barley. For the sake of comparison, I 

 introduce the results obtained by the application of common salt 

 as well as saltpetre in the following experiments. It is to be 

 regretted that nitrate of soda, applied alone, was not tried at 

 the same time. 



a Mr Melvin, near Eatho, Mid-Lothian 



Grain. Straw. Weight per bushel. 



No application gave . 41 bush. 25 cwt. 53^ lb. 



Nitrate of potash, 1 cwt., 44 ... 28 ... 52f ... 



Common salt, 2 cwt,, . 44 ... 24 ... 53 ... 



Z> Mr Fullerton, near Brechin, Forfarshire 



Grain. Straw. Weight per bushel. 



Nothing gave . . 44 bush. 28 cwt. 5J^lb. 



Nitrate of potash, 200 lb. 50 ... 31 ... 51^ ... 



Common salt, 200 lb. . 40 ... 25 ... 52f ... 



c Mr Proudfoot, near Musselburgh, Mid-Lothian 



Grain. Straw. Weight per bushel. 



Nothing gave . . 56 bush. 32 cwt. 57 lb. 

 Nitrate of potash, 140 lb. 56 ... 34 J . . . 57 ... 



Common salt, 3 cwt., . 58 ... 31 f ... 57... 



