114 SoiJie Causes of Unproductiveness in Soils. 



may yet assert that neglect of chemical principles frequently leads 

 to practical mistakes. Such mistakes are often unconsciously 

 committed by excellent farmers, on whose authority good, as well 

 as bad practices are handed on from one generation to another. 



The causes of barrenness or unproductiveness of soils are 

 numerous : some depending more obviously on the imperfect 

 chemical constitution of the land, may be conveniently termed 

 chemical causes of barrenness ; others, like those manifesting 

 themselves in too close or too loose, or otherwise faulty a texture, 

 may be termed physical or mechanical causes of unproductiveness. 

 It is not easy to separate the one class from the other ; for in reality 

 the imperfect chemical constitution of land frequently is but the 

 result of its bad physical condition. Thus, undrained, unmiti- 

 gated clay soil, does not yield to the growing plant a sufficiency 

 of available potash, phosphoric acid, lime, &c., and may be said 

 to be unproductive as much on account of its lack of available 

 plant-food, as on account of its bad physical condition. 



A recognition of the cause of sterility in land often enables the 

 intelligent agriculturist to apply the proper means of restoration. 

 Barrenness and comparative unproductiveness may be due to a 

 variety of causes : sometimes it arises from a deficiency in the soil 

 of something essential to the healthy growth of plants ; in another 

 soil it is the result of the presence of something injurious to vegeta- 

 tion ; and in a third case it is the impervious character of the land 

 which causes it to be unproductive. Any defect must be dis- 

 covered before it can be supplied, and the remedy against any 

 injurious substance present in the land is not likely to be found 

 so long as its precise chemical composition is unknown. 



It is not a little amusing to find agricultural writers speaking 

 of the bad chemical composition, or the poor physical cha- 

 racter of the land as the cause of its unproductiveness. What 

 the chemical composition of the land really is, or what is the 

 precise nature of its poor physical character, for obvious reasons, 

 we are not told. No wonder that plain and intelligent men 

 lightly esteem the chemical theories and the physical explanations 

 by which attempts are made to enlighten the agricultural mind 

 as to the causes of barrenness of soils. 



The present paper only professes to treat of certain of the 

 causes of barrenness, which I have myself investigated more 

 particularly. 



In reviewing the inquiries purposely instituted by me, and the 

 cases with which I became incidentally acquainted, soils appear 

 to be barren, or more or less unproductive, — 



1. When they contain something inimical to vegetation. 



2. When they are deficient in one or more important con- 

 stituents which enter into the organization of the living plant. 



