AGRICULTURAL GEOLOGY. 195 



7. We give one more analysis, being that of a soil from Rensse- 

 laer county : color brownish drab, and texture coarse. 



Water 250 



Vegetable matter 400 



Silex 8000 



Alumina 4'00 



Peroxide of iron 400 



Phosphate of magnesia - - - 300 



Carbonate of lime . - - . 200 



99-50 



We have selected the foregoing analyses out of many which we 

 have on hand, for the purpose of showing that although limestone 

 exists abundantly in our district, it is contained only in small pro- 

 portion in the surface soil, while we find magnesia in almost every 

 specimen. This last is an important element, and we consider its 

 presence as explaining why this region is so well adapted to the 

 raising of maize or Indian corn. Phosphate of magnesia, it is now 

 known, enters into the composition of this grain ; and it is highly 

 probable that, where this substance is deficient, corn does not reach 

 perfection. 



An improvement proposed. 



This consists in deep draining. We have observed many farms, 

 with an acre situated as represented in the following diagram : 



Fig. 2. 



At a is a hardpan (with the soil upon it), say eighteen inches below 

 I the surface, and the slope extending towards h. Lands thus situated, 

 and based upon a hardpan or stiff clay subsoil, will be invariably 

 too wet. At G, springs frequently gush out ; and the whole slope, 

 though well exposed, will be inclined to produce the poorer grasses, 

 and to become mossy ; and although no water appears on the sur- 

 face, yet it subsides so slowly that the temperature is always low. 

 The only remedy in such cases is deep draining. Places of this 

 description are so numerous in the Taconic region, on both sides 

 of the range, that it appeared proper to call attention to the subject. 



VOL. II. — NO. II. C 





