312 TALKS ON MANURES. 



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

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

 teriorated. It has contained less nitrogen and mure 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 anmionia 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, tiic better plan is to sow them 

 broadcast, and it is important to di.^lribute 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 s(iuare yard, it will l)urn up the crop, and the other 

 half will be api»lied 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 mi.x them with sifted 

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



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

 ing cartii or as'jcs 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 ; mraonia 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. 



Carbonat(> of ammonia contains 21 i per cent of ammonia. 



Sulphate of ammonia contains 25| per cent of ammonia=21V» 

 of nitrogen. 



