36 LIFE ON THE FARM. 



muck. These soils are such because of the great 

 amount of water they contain, and of their anti- 

 septic nature, shutting out those organisms which 

 cause decomposition. They become very pro- 

 ductive when drained, as this allows air and 'decom- 

 position germs to enter them. 



It must be borne in mind that the humus soils 

 are the most unstable. In the decay of the organic 

 matter of which they are composed, part of the 

 products go back to the earth as ash, and part as 

 gases to the air from whence they came. All 

 organic substances remain but a short time as such, 

 then decompose into their original elements, to be 

 again taken up and passed through the cycle of life. 



ELEMENTS COMPOSING THE SOIL. 



Each rock has its own particular composition, 

 and the elements composing any single kind are 

 so few in number that they are not adequate for 

 the many demands of plants; but there has been 

 such thorough grinding and mixing in the processes 

 of soil-building that many different kinds of ele- 

 ments have been brought together and can be 

 found in almost all places. The elements compos- 

 ing the soil rarely occur in a free state, but are 

 usually combined with other elements to form com- 

 pounds. Some of the most important elements 

 are oxygen, hydrogen, nitrogen, sulphur, silicon, 

 phosphorus, chlorine, calcium, aluminum, iron, 

 sodium, magnesium, and manganese. 



