INORGANIC ELEMENTS OF MANURES AND CROPS. 371 



analyses were made with ashes furnished by the crops of 1841 and 

 1842. 



I. II. III. Average 



(Carbonic 9.0 5.5 " 7 3 



Acids < Phosphoric 5.3 5.3 5.5 5.4 



(Sulphuric 2.4 2.9 " 2.7 



Chlorine 2.3 2.8 " 2.6 



Lime 20.4 15.4 " 17.9 



Magnesia 6.0 8.3 " 7.2 



Potash 16.1 27.3 " 21.7 



Soda 1.2 2.3 " 1.8 



Silica 33.7 29.2 " 31.5 



Oxide of iron, &c 1.5 0.6 0.5 0.9 



Loss 2.1 0.4 " 1.0 



100.0 100.0 100.0 



No. 1 yielded 6.0 per cent, of ash. 



No. 2 " 6.2 idem. 



In admitting as the average yearly return of our irrigated mead- 

 ows, 3666 lbs. of hay and after-grass for the acre, it appears that 

 we obtain, from a corresponding surface of land, 223.6 lbs. of ash, 

 containing : 



(Carbonic 16.3 



Acids < Phosphoric 12.1 



(Sulphuric 6.0 



Chlorine 5.7 



Lime 39.1 



Magnesia 16.1 



Potash and soda 52.0 



Silica 70.4 



Oxide of iron, andloss:. 4.2 



221.9* 



In reckoning, as I have done, the lowest annual exportation of 

 mineral substance from one acre of arable land at 5.5 lbs. of phos- 

 phoric acid and 8.2 lbs. of alkali, (potash and soda,) there must, in 

 order to make up for loss, arrive each year at the farm a quantity 

 of hay corresponding to about 1800 lbs. for every acre of ploughed 

 land, which would establish between the arable and meadow land, a 

 relation somewhat less than 1 to ^. 



In practice, the relation in question is sensibly less than that de- 

 duced from analysis ; in some farms the meadow-land only occupies 

 a fourth or fifth of the whole surface. When rye replaces wheat, 

 the extent in meadow-land may be still more limited. It deserves 

 notice, that I have supposed the arable land as destitute of proper 

 inorganic matter, and that all came from the manure ashes and lime 

 laid on, which is not rigorously true. Tnere are soils containing 

 traces of phosphates, and it is difficult to find clay or marl exempt 

 from potash. Nevertheless, many clear-headed practical men begin 

 to suspect that meadow has been too much sacrificed to arable land. 

 In localities placed in similar conditions to those in which we are, 

 removed from every source of organic manures, which, as I have 

 shown in concert with M. Payen, are always furnished with saline 



* The sura Is only too small here from the number of places of dedtnals not havli|| 

 been carried out far enough. — Evo. Ed. 



