in.] ACTIVE AND DORMANT MATTER. 23 



38. Whilst the active ingredients of the soil are 

 useful for the immediate requirements of vegetation, 

 the dormant ingredients have also their duties 

 to fulfil. These constitute the reserve_jun_d of 

 the soil, and secure its future fertility! A bad 

 farmer may rob the land of very much of its active 

 matter, and by frequent removal of crops from the 

 land take away its immediate fertility, but he cannot 

 take away that which is in a dormant condition. It 

 is only the good farmer who gets help from this store ; 

 and we shall hereafter point out why the one is re- 

 warded by good crops, whilst the other is punished 

 for his bad management. For the present it is enough 

 to remember that the dormant matter of soils is a 

 reserve of fertility for future years. 



39. It will be important to know how this dor- 

 mant matter becomes useful for vegetation. 

 It is changed into the active condition in the 

 following manner. You have seen that the rain-water, 

 containing as it does carbonic acid and oxygen, and 

 also the frost, break down even the hardest rocks, and 

 by their continued action they at length dissolve up 

 much of the finely broken portions of these rocks. 

 Exactly the same result is accomplished in the soil by 

 exposing it to the air, rain, and frost, and by allowing 

 the rain to pass into and through the soil ; thus when 

 the soil of a field is ploughed up roughly before 

 winter, and exposed to the air, rain, and frost, it 

 is not only broken up into fine condition, but the surface 

 of the little fragments of the soil is so acted upon that 

 some portions become soluble in water, and 

 ready for being taken into the circulation of the plant. 

 These are some of the natural agencies by which a 

 part of the dormant matter is made ready for vegeta- 

 tion by becoming active ; there are other means for 

 assisting the same change, but these will be more 

 conveniently noticed hereafter. 



40. We have already noticed the fact that plants 



