MANURES. 83 



Loiice it is a chemical manure. In c ther words, pot- 

 asli belongs to both classe" described. 



It is important that thif "ilistinction should be well 

 understood by the learner^ as the words " mechani- 

 cal " and " chemical " in connection with manm-cs 

 will be made use of through the following pages. 



There is another class of manures which we shall 

 call absorbents. These comprise those substances 

 which have the power of taking up fertilizing mat- 

 ters, and retaining them for the use of plants. For 

 instance, charcoal is an absorbent. As was stated 

 in the section on soils, this substance is a retainer 

 of all fertilizing gases and of many minerals. 

 Other matters made use of in agriculture have the 

 same effect. These absorbents will be spoken of 

 more fully in their proper places. 



TABLE. 



Mechanical Manures are those which improve the 

 mechanical conditions of soils. 



Chemical " are those which serve as food 



for plants. 



MANURES. 



Absokbents are those substances which absorb and 

 retain fertilizing matters. 

 Manure may be divided into three classes, viz, : 

 organic, mineral, and aimosjpherio. 



