304 BOARD OF AGRICULTURE. [Jan. 



glaciated belt, except those of a swampy nature, have 

 sufficient vegetable matter in their mass, say for the depth 

 of a foot below the surface, to serve the needs of plant life. 

 It is very desirable to increase this amount of vegetable 

 waste as rapidly as possible, and to extend it to the depth 

 of at least a foot below the surface. It is a well-known fact 

 that the process by which the mineral matter is converted 

 into the state in which it may serve for plant food is mainly 

 effected by reactions, which depend upon the decay of 

 carbonaceous or other organic material beneath the surface 

 of the soil. A certain amount of work of this nature is 

 done by the water, which obtains carbonic acid gas and 

 nitro-humic acids from the surface, and passes them down- 

 ward in its descent into the soil ; but it seems pretty certain 

 that the whole of the work cannot be accomplished in this 

 manner, but is best attained by the actual commingling of 

 decaying vegetable material with the mineral grains of the 

 detritus. Therefore, in glacial districts generally even more 

 than in soils of other character, it is desirable to plough in 

 such crops as may fitly serve this end. 



It should be observed, as before noted, that glacial soils 

 are commonly composed in large proportion, generally to the 

 extent of more than half of their bulk, of pebbles, containing 

 a variety of mineral constituents. It is very desirable to 

 promote the decay of these fragments, for from them there 

 is a constant contribution of various valuable mineral ele- 

 ments, — lime, potash, soda, phosphatic matter, etc., — 

 which are immediately necessary to plant growth. A peb- 

 ble of granite rock, lying in the ordinary conditions in which 

 it is deposited by glacial action, decays very slowly. If, 

 however, it be enveloped in decomposing vegetable matter, 

 the process of solution is rapidly advanced. A familiar 

 instance of this may be perceived in the case of organic rocks 

 which have been long buried in swamps. The reader may 

 have ol^served, that, when these fragments are removed to the 

 open air, they have a singularly white color ; this hue is due 

 to the decay or kaolinization of the feldspar, a process which 

 aids in its solution in water. He will also observe that the 

 outside of such stones is commonly very rotten, the surface 

 readily falling to pieces by the friction from his hand. He 



