AGRICULTURAL TEXT-BOOK. 



307 



The result certainly astonished me, for it was in direct antagonism to all precon 

 ceived notions of farmers ; as it is usually thought by them that crops do not impov 

 erish the ground, nearly to the same extent, when cut green, as when allowed to ri 

 pen their seed. Turnips, too, are generally supposed to extract the greater portion of 

 their nourishment from the atmosphere. But here we find that beans actually re 

 fused to grow after the green-rye and turnips, notwithstanding the application of 

 three cwt of guano, and the land being in much better tilth ; where the rye was al 

 lowed to ripen its seed, and no extra manure applied they grew luxuriantly. 



I determined to inquire whether the researches of chemists would throw any 1 ght 

 upon the question ; and the difficulty I had in compiling the following small tables, 

 fully accounts to my mind for the fact that chemistry has hitherto received so little 

 assistance from practical farmers. 

 Probable Amount of Ingredients abstracted from or restored to One acre of Land by 



the several Crops and Manures of Rotation I, (Seeded Kye and Beans.)* 



Rotation 2, (Green Rye, Turnips, and Beans.) 



Mr. Hemming calculated in the same manner every constituent of the plant, but 

 the size of our pa^e obliges us to give those only which are most essential to growrh. 



Cf The mark ( ) means minus, or that the turnips abstracted 32 Ibs. more Potasb 

 than had been supplied to the soil by the manure and other sources, hi the last line 



