ALLEGED REMOVAL OF LIME BY WATER. 



201 



According to this statement, during the rotation of five years, 

 the total amount of pure lime taken up by the potato crop, and 

 three grain crops, was 4 Ibs. The turnips, straw, and clover, took 

 up 120 Ibs. The former quantity, equal to the yearly average of 

 0.8 Ibs., is all that may be supposed to be removed from the farm. 

 The latter, of 24 Ibs. a year in the turnips, litter and hay, must be 

 returned to the farm in manure. Both these quantities are still less 

 than by the foregoing estimate, quoted by Johnston. Both are so 

 minute as scarcely to be appreciable; and all such loss would 

 scarce deserve consideration, as a practical matter, but for the false 

 importance which has been given to this manner of abstraction of 

 lime from land. 



The ordinary farm-made manures, with some purchased peat- 

 ashes, composed the manure applied by Boussingault, in each ro- 

 tation ; and which served to supply to the soil much more of all 

 the mineral parts than were taken up by the crops of all kinds. 

 Of course, there could have been no deficiency of supply of lime 

 for the use of the growing plants, nor any less taken up by them 

 than they required. 



2. Another waste of lime alleged by Prof. Johnston is by solu- 

 tion in rain (or other) water. He says : " In the quick or caustic 

 state, lime is soluble in pure water, 750 Ibs. of water serving to 

 dissolve 1 Ib. of lime. The rains that fall cannot fail, as they sink 

 through the soil, to dissolve and carry away a portion of the lime 

 so long as it remains in the caustic state. Again, quick -lime, 

 mixed with the soil, speedily attracts carbonic acid, and in time 

 becomes the carbonate, which is nearly insoluble in pure water, 

 but is soluble in water impregnated with carbonic acid ; and as the 

 drops of rain in falling absorb this acid from the air, they become 

 capable, when they reach the soil, of dissolving an appreciable 

 quantity of the finely-divided carbonate of lime on cultivated fields. 



