THE FOOD OF PLANTS. 273 



body, and has neither taste, color, nor smell. It 

 cannot be burned, it will not support combustion, 

 and it cannot be breathed into the lungs. It is a 

 strange, negative element, and yet without its in- 

 fluence not a stalk of corn nor a blade of wheat can 

 grow. It is the most costly of all our fertilizing 

 agents, and yet millions and billions of tons are 

 present in the air constantly, and every plant is 

 surrounded by and immersed in it. Is not this 

 statement perplexing or paradoxical ? Nitrogen as 

 it exists in nitrogenous bodies is alone available for 

 plants, and the cheapest source, outside of refuse 

 animal compounds,- is in the form of nitrate of soda. 

 This salt, known as Chilian saltpetre, is sold at the 

 present tinie at about four cents per pound, whi'ch 

 makes the nitrogen it contains cost about twenty- 

 eight cents per pound. The nitrogen in sulphate of 

 ammonia, at present market rates, costs thirty-five 

 cents, and I have not found it so readily available, 

 or prompt in its action upon my fields. For grass 

 lands, as a top dressiifg, the nitrate of soda has 

 proved with me a profitable agent. It brings in 

 the better quality of grasses, and largely increases 

 the crops. It should be pulverized fine, mixed 

 with an equal quantity of fine seasoned peat, and 

 sown evenly over the field, giving to each acre two 

 or three hundred pounds of the salt. Without a 

 supply of nitrogenous food plants become feeble 

 18 



