44 w ALL'S MANUAL 



ous substances to nearly all cultivated soils. We have 

 to furnish to the soil such ingredients as are needed 

 by plants, and which in many places are found quite 

 sparingly in the soil. These ingredients are phosphate 

 of lime, potash, soda, and ammonia which, with mold 

 and the other mineral manures already in the soil, 

 will produce plentiful crops. Other matters intro- 

 duced into the soil are classed as mechanical agents, 

 and effect, principally, the texture and physical 

 properties of the same. They frequently are as 

 valuable as the nutritive manures themselves, in 

 giving the soil its best mechanical qualities as to 

 structure, as dryncss or moisture, rctentiveness of 

 heat, and such a degree of porosity as to enable the 

 air to penetrate deep down into the soil. Charcoal 

 powder acts mechanically in absorbing ammonia and 

 moisture from the air, and also, by its color, in absorb- 

 ing the heat of the sun's rays, and retaining the heat 

 by imperfect conduction. Cbarcoal is undoubtedly a 

 powerful fertilizer, and one of great duration, as is 

 shown by the continued fertility of the places \\ here 

 the Indians built their camp-fires. On the banks of 

 James Eiver, in Virginia, more than two hundred 

 years ago, this evidence is strikingly shown. iSTothing 

 peculiar to these spots can be discovered, beyond the 

 admixture of large quantities of charcoal and oyster 

 shells with the soil. Carbonate of lime, shells, marl 

 or limestone, in excess, is also highly useful in any 

 soil; as it stands ready to take up any acid matter, 

 whether of vegetable or mineral origin, and on com- 

 bining with them, gives off carbonic acid, which goes 

 not only to decompose the silicates in the soil, but 

 also rises through it to nourish the foliage of plants. 



