MEDIUM RED CLOVER III 



nitrogen is drawn in great part from the air; com 

 sequently, soil from which a bountiful crop of clo- 

 ver has been removed will be considerably richer in 

 nitrogen than before it grew the same, and this will 

 hold true as intimated above, even though the crop 

 should be removed and sold. Under the same condi- 

 tions it will also be true in available phosphoric 

 acid and potash. But the latter are gathered from 

 the soil and subsoil while the plants were growing. 

 Consequently, if crops of clover are grown in short 

 rotation periods and if no fertilizer is given to the 

 land other than the clover brings to it, while it will 

 be abundantly supplied with nitrogen, a time will 

 come when the supply of phosphoric acid and potash 

 may be so reduced that the soil will not grow even 

 good crops of clover. When this point is reached 

 the soil is spoken of as "clover sick." Happily, how- 

 ever, nearly all soils are so well stored with phos- 

 phoric acid and potash that this result is not likely 

 to follow for many years. But lest it should, atten- 

 tion should be given to fertilizing the land occasion- 

 ally with farmyard manure, or with phosphoric acid 

 and potash applied as commercial fertilizers. Be- 

 cause of this, and also for other reasons, it is usu- 

 ally considered more profitable in the end to feed 

 clover on the farm and return it to the land in the 

 form of manure. But clover may cease to grow on 

 land where once it grew well, because of other rea- 

 sons, such as changes in the mechanical condition of 

 the soil caused by the depletion of its humus and 

 changes in its chemical condition, such as increased 

 acidity. The remedy is the removal of the cause. 



