LIME AS A MANURE. 215 



from the animals kept on the farm. They know what manures cost 

 and what they are worth. As a rule, too, such men are good farm- 

 ers, and endeavor to work their land thoroughly and keep it clean. 

 When this is the case, there can be little doubt that we can often 

 use artificial manures to great advantage. 



" You say," said the Deacon, who had been looking over the 

 tables while I was talking, "that mixed mineral manures 

 and 50 Ibs. of ammonia give 39| bushels per acre. ' Now these 

 mixed mineral manures contain potash, soda, magnesia, and super- 

 phosphate. And I see where superphosphate was used without any 

 potash, soda, and magnesia, but with the same amount of ammonia, 

 the yield is nearly 46 bushels per acre. This does not say much in 

 favor of potash, soda, and magnesia, as manures, for wheat. Again, 

 I see, on plot 10&, 50 Ibs. of ammonia, alone, gives over 43^ bushels 

 per acre. On plot 11&, 50 Ibs. ammonia and superphosphate, give 

 46 bushels. Like your father, I am inclined to ask, * Where can I 

 get this ammonia?'" 



CHAPTER XXVIII. 

 LIME AS A MANURE. 



These careful, systematic, and long-continued experiments of 

 Lawes and Gilbert seem to prove that if you have a piece of 

 land well prepared for wheat, which will produce, without manure, 

 say 15 bushels per acre, there is no way of making that land pro- 

 duce 30 bushels of wheat per acre, without directly or indirectly 

 furnishing the soil with a liberal supply of available nitrogen or 

 ammonia. 



" What do you mean by directly or indirectly ? " asked the 

 Deacon. 



" What I had in my mind," said I, " was the fact that I have 

 seen a good dressing of lime double the yield of wheat. In such 

 a case I suppose the lime decomposes the organic matter in the 

 soil, or in some other way sets free the nitrogen or ammonia 

 already in the soil ; or the lime forms compounds in the soil which 

 attract ammonia from the atmosphere. Be this as it may, the 

 facts brought out by Mr. Lawcs' experiments warrant us in con- 

 cluding that the increased growth of wheat was connected in some 

 way with an increased supply of available nitrogen or ammonia. 



