[365] SCIENTIFIC MANUAL. 79 



4. It furnishes a considerable portion of carbon to plants 

 either directly or indirectly. 



5. In its widest sense, it supplies the mineral elements 

 of decayed matter in soluble forms for plant-food. 



6. It absorbs and ; holds free ammonia and its carbonate, 

 and thus supplies plants. 



7. It absorbs lime and its carbonate, and renders it as- 

 similable as plant-food. 



8. It furnishes a solvent to the soil (carbonic acid), for 

 the silicate of potash and phosphate of lime, by which 

 plants are supplied with the two important compounds, 

 phosphoric acid and potash. 



9. In warm climates, it cools the soil by the alternate 

 imbibition and evaporation of moisture. 



10. It is, in fact, a prime agent in the laboratory of na- 

 ture, for carrying on chemical changes in soils, producing 

 heat, evolving carbon, oxygen, and hydrogen, as well as 

 nitrogen, obtained by absorption. [Scientific Agricul- 

 ture. Pendleton. ] 



One of the causes of the remarkable effects of composts 

 upon the denuded soils of Georgia, may be attributed to 

 the humus which they contain. 



A word of caution in relation to the use of lime, may pre- 

 vent disastrous results to the inexperienced. Lime should 

 not be applied to soils deficient in vegetable matter, without a 

 simultaneous application of either coarse manure or vege- 

 table matter of some kind. 



It should not, however, be mixed with animal manures, 

 or any other containing any considerable percentage of ni- 

 trogen, before it is spread upon the soil. It converts ni- 

 trogen into ammonia, which is volatile, and will pass off 

 as a gas into the atmosphere. 



This action of liberating ammonia is beneficial if it takes 

 effect in the soil, where it is immediately absorbed and re- 

 tained, by humus or clay, for the use of plants. 



These cautions apply only to quick-lime, or the carbon- 



