312 TALKS ON MANURES. 



est and best source of available nitrogen. But latterly, not only 

 has the price been advanced, but the quality of the guano has de- 

 teriorated. It has contained less nitrogen and more phosphoric 

 acid. See the Chapter on " Value of Fertilizers," Page 324. 



SALTS OF AMMONIA AND NITRATE OF SODA. 



" I wish," said the Deacon, " you would tell us something about 

 the ' ammonia-salts ' and nitrate of soda so long used in Lawes and 

 Gilbert's experiments. I have never seen any of them." 



" You could not invest a little money to better advantage than 

 to send for a few bags of sulphate of ammonia and nitrate of soda. 

 You would then see what they are, and would learn more by using 

 them, than I can tell you in a month. You use them just as you 

 would common salt. As a rule, the better plan is to sow them 

 broadcast, and it is important to distribute them evenly. In sowing 

 common salt, if you drop a handful in a place, it will kill the 

 plants. And so it is with nitrate of soda or sulphate of ammonia. 

 Two or three pounds on a square rod will do good, but if you put 

 half of it on a square yard, it will burn up the crop, and the other 

 half will be applied in such a small quantity that you will see but 

 little effect, and will conclude that it is a humbug. Judging from 

 over thirty years' experience, I am safe in saying that not one man 

 in ten can be trusted to sow these manures. They should be sown 

 with as much care as you sow grass or clover-seed." 



"The best plan," said the Doctor, "is to mix them wi:h sifted 

 coal-ashes, or with gypsum, or sifted earth." 



" Perhaps so," said I, " though there is nothing gained by mix- 

 ing earth or ashes with them, except in securing a more even dis- 

 tribution. And if I was going to sow them myself, I would much 

 prefer sowing them unmixed. Any man who can sow wheat or 

 barley can sow sulphate of ammonia or nitrate of soda." 



" Lawes and Gilbert," said the Deacon, " used sulphate and mu- 

 riate of ammonia, and in one or two instances the carbonate of 

 ammonia. Which is the best ? " 



" The one that will furnish cmmonia or nitrogen at the cheapest 

 rate," said the Doctor, " is the best to use. The muriate of ammo- 

 nia contains the most ammonia, but the sulphate, in proportion 

 to the ammonia, is cheaper than the muriate, and far cheaper than 

 the carbonate. 



Carbonate of ammonia contains 21 per cent of ammonia. 



Sulphate of ammonia contains 25$ per cent of ammonia = 21 Y 6 

 of nitrogen. 



