HOW TO PROCURE TREES. SI 



the rains would soon carry down the virtues, 

 while the loss by evaporation would be much 

 less than is generally supposed. It is upon 

 this theory that the practice of top-dressing of 

 lands has been so general. But modern inves- 

 tigations seem to demonstrate that fermenta- 

 tion is a decided benefit to stable manures. It 

 is caused by the amazing development of bac- 

 teria working with surprising rapidity in a 

 congenial material, similarly as yeast works 

 in dough, and thereby not merely raising the 

 temperature of the mass and reducing the 

 organic matter to a soluble condition, but also 

 by the prodigious increase and decay of the 

 microbes adding materially to the strength of 

 the fertilizer. However much may be added 

 by these minute organisms, it is at least cer- 

 tain that the mass is reduced to a much better 

 condition as plant food by proper fermenta- 

 tion. But it is important that this process 

 should be under careful control. If the heat 

 becomes excessive, there is great loss of am- 

 monia, the heap becomes " fire-fanged " and 

 almost worthless. The practice of frequent 

 turning can hardly be considered economical, 

 since the exposure to the air at each turn- 

 inc involves the loss of ammonia. The best 

 mode of treatment undoubtedly is to draw the 



