SECTION IV.—QUANTITY OF INORGANIC MATTER CONTAINED IN AN ORDINARY CROP OR SERIES OF CROPS. The importance of the inorganic matter contained in living vegetables, or in vegetable substances when reaped and dry, will appear more distinctly if we consider the actual quantity carried off from the soil in a series of crops. In a four-years’ course of cropping, in which the crops gathered amount per acre to— 1st year, _Turnips_, 25 tons of bulbs, and 7 tons of tops. 2d year, _Barley_, 38 bushels of 63 lbs. each, and 1 ton of straw. 3d year, _Clover and Rye Grass_, 1 ton of each in hay. 4th year, _Wheat_, 25 bushels of 60 lbs., and 1¾ tons of straw. The quantity of inorganic matter carried off in the four crops, supposing none of them to be eaten on the land, amounts to— Potash, 281 lbs. Soda, 130 ” Lime, 242 ” Magnesia, 42 ” Alumina, 11 ” Silica, 318 ” Sulphuric acid, 111 ” Phosphoric acid, 61 ” Chlorine, 39 ” -------- Total, 1240 or, in all, about 11 cwt.—of which gross weight the different substances form very unlike proportions. A still clearer idea of these quantities will be obtained by a consideration of the fact, that if we carry off the entire produce, and return none of it again in the shape of manure, we must or ought in its stead, if the land is to be restored to its original condition, add to each acre every four years:— Pearl or Potash, 390 lbs. at a cost of _l._3 10 0 Crystallized carbonate of soda, 440 2 5 0 Common salt, 65 0 2 0 Quick (burned) lime, 240 0 1 0 Epsom salts, 250 1 5 0 Alum, 84 0 8 0 Bone-dust, 260 0 16 0 ------ --------- Total, 1729 _l._8 7 0