AGRICULTURAL TEXT-BOOK. 



Besides these constituents, a good wheat soil should contain 

 a notable proportion of potash, soda, phosphoric acid, and nitro 

 gen. In Great Britain, the introduction of turnips and clover 

 culture and drainage has greatly extended the range of wjieat 

 producing soils; this grain being now cultivated in rotation, 

 with profit, even on sandy soils ; so true is it, that science can 

 adapt the earth and climate to almost any crop which it is de 

 sirable to cultivate. 



174. &quot;Wheat, is considered a scourging crop, rapidly impov 

 erishing the soil, in consequence of its requiring for its compo 

 sition large quantities of materials, chiefly inorganic, which are 

 naturally rare in soils. In this respect, it is placed at the head, 

 of grains. According to Boussingault, a medium crop of wheat 

 takes from one acre of ground : 



