80 CHRONICLES OF A CLAY FARM. 



substituted by green crops ; it must yet be borne in 

 mind that it is not in the mechanical structure alone 

 that heavy soils differ from light soils ; their chemical 

 difference, which is quite as great, lies in that 

 essential particular that the clay soil is naturally 

 richer in the mineral constituents required by your 

 crops. Potash, Soda, and Phosphorus, which you 

 must supply to a light soil before you sow it, you 

 have only to develope in a clay soil by deep and 

 frequent stirring, and submitting it to the oxidation 

 of the atmosphere. The green-crop, with its carbon- 

 obtaining leaves, will no doubt supply organic wealth 

 to either ; but inorganic food can come from the soil 

 alone ; and if the soil be able to supply it from its 

 own resources, one-half the value of the green-crop, 

 as a fertilizer, is renounced. Its remaining value, 

 as a collector of organic matter from the atmosphere, 

 is the point upon which the question will be poised, 

 of its adoption on a soil which, after effectual 

 drainage, sub-pulverization, and liming, still retains 

 the character of a ' clay.' Even upon such land, 

 (which is not so plentiful as some imagine,) expe- 

 rience has yet to prove how far, by deep ploughing 

 and subsoiling immediately after harvest, and 

 making the most of suitable weather between that 



