214 CULTIVATION. 



the next thaw leaves them higher than ever, until in 

 spring, sometimes, the crown of a shoot of wheat 

 will be standing several inches above the level of 

 the soil. The use of a mulch prevents both the 

 freezing and the thawing from being so frequent and 

 active as they would be if no protection were used. 



7. It also prevents the " baking " of the soil, or the 

 formation of a crust. 



Nursery-men often keep the soil about the roots of 

 young trees mulched continually. One of the chief 

 arguments for this treatment is, that it prevents the 

 removal of the moisture from the soil and the conse- 

 quent loss of heat. Also that it keeps up a full sup- 

 ply of water for the uses of the roots, because it keeps 

 the surface of the soil cool, and causes a deposit of dew. 



It has been suggested, and is undoubtedly true, that 

 a mulch on the ground, by affording a good shelter for 

 minute (microscopic) insects, causes them to accumu- 

 late in such quantities as to add (by their eggs, their 

 excrement, and their dead bodies) to the fertilizing 

 matter in the soil. How important this addition 

 may be, we cannot of course know, but it is certain 

 that mulching exercises greater good effect than can 

 reasonably be attributed, in the present state of our 

 knowledge, to any or all of the above described actions. 



It is the opinion of many, that at least one-half of 

 the beneficial effect of seaweed, or coarse stable ma- 

 nure, when used as a top dressing, is due to its action 

 as a mulch. 



It is a good plan to sow oats very thinly over land 

 intended for winter fallow, after the removal of crops, 



