128 Some Causes of Unproductiveness in Soils. 



the herbage. It is not for mc to say whether it is profitable to 

 put such land down in permanent pasture or to break it up and 

 adopt upon it a rotation suited to heavy clay land ; but of this I 

 am quite certain, that the steam-cultivator would do wonders on 

 these cold, stiff clays, for they contain, practically speaking, an 

 inexhaustible store of mineral food of plants, which, however, 

 has to be unlocked as it were by the air. The more roughly stiff 

 clavs are broken up the better ; the less the farmer meddles with 

 the land when once broken up, the more effectually the air will 

 find access into the land. No imjdement can possibly pulverise 

 clays so effectually as air and irost, if time be allowed. 



Having spoken at some length of a variety of conditions 

 which appear to me to affect the fertility of land, my subject 

 perhaps may be usefully brought to a close by a brief statement 

 of what in my opinion the chemical analysis of soils can de- 

 termine, and what it necessarily must leave undecided. 



In the first place I would remark, that the chemical analyses of 

 soils can give very decided answers to the following questions : 



1. Whether or not barrenness is caused by the presence of an 

 injurious substance, such as sulphate of iron or sulphide of iron? 



2. Whether soils contain common salt, nitrates, or other 

 soluble salts, that are useful when highly diluted, but injurious 

 when they occur too abundantly ? 



3. Whether or not barrenness is caused by the preponderance 

 of— 



Organic matter, or 

 Lime, or 

 Sand, or 

 Pure clay ? 



4. Whether sterility is caused by the absence or deficiency 

 of— 



a. Lime. 



h. Phosphoric acid. 



c. Alkalies, especially potash. 



d. Or available mineral (ash-constituents) matters generally ? 



5. Whether clays are fertile or barren ? 



G. Whether or not clays are usefully burnt and used in that 

 state as manure? 



7. Whether or not land will be improved by liming? 



8. Whether it is better to apply lime or marl or clay on a 

 particular soil ? 



9. Whether special manures, such as superphosphate or ammo- 

 niacal salts, can be used (of course discreetlv) without permanently 

 injuring the land, or whether the farmer should rather depend 

 upon the liberal application of farmyard-manure that he may 

 restore to the land all the elements of fertility removed in the crops? 



