CHANGES IN INORGANIC CONSTITUENTS. 285 



silicates, carbonates, phosphates, humates, sulphates, etc. In humid 

 climates the carbonates are being continually removed from weathered 

 rock material, as is plainly shown by the composition of drainage 

 waters. The losses become much greater in cultivated soils thanks 

 to the humus and the microorganisms present in them. The absolute 

 amounts lost from year to year will depend on the proportion of lime and 

 magnesia in the soil, the mechanical composition of the latter, its content 

 of humus and the methods of tillage and fertilization. According to Hall 

 the soils of the experiment fields at Rothamsted, containing about 3 

 per cent of calcium carbonate, are losing lime at the rate of 362 kg. 

 to 453 kg. ( 800 to 1,000 pounds) per acre annually. In certain 

 sections of Scotland where liming has been practised for a long time the 

 farmers estimate the loss of lime from the land at 6 bushels per 

 acre, annually; that is, approximately at the rate of 226 kg. to 272 

 kg. (500 to 600 pounds). In New Jersey, New York, Pennsylvania and 

 other eastern states farmers who use lime more or less regularly apply one 

 ton of it at the beginning of each five year rotation. This would provide 

 for an annual loss of 181 kg. (400 pounds) per acre. The loss of 

 lime and magnesia is increased under intensive methods of agriculture. 

 When animal manures and green manures are employed, microbial 

 activities are stimulated, the production of carbon dioxide is encouraged 

 and the loss of the soluble calcium bicarbonate made greater. The re- 

 moval of lime is hastened even to a more striking extent when ammonium 

 salts are applied to the land. The resulting nitrification and loss of lime 

 are illustrated by the following equation: 



(NH 4 ) 2 SO 4 + 2CaCO 3 + 4O 2 = Ca(NO 3 ) 2 + CaSO 4 + 4H 2 O + 2CO 2 



As was already indicated, the loss of calcium and magnesium carbonate 

 from the soil is effected largely through the activities of bacteria and of 

 other microorganisms. At the same time microorganic life is responsible 

 for the restoration of varying amounts of carbonates. It has been dem- 

 onstrated that, in the weathering of the complex silicates, carbonates and 

 silicic acid may be formed in considerable quantities. In the presence 

 of decaying organic matter and the consequent evolution of carbon diox- 

 ide the formation of carbonates from silicates may be extensive enough to 

 balance the losses. Similarly, calcium carbonate may be formed in the 

 soil from humates and from the calcium salts of simpler organic acids. 

 They may be formed, also, through the activities of denitrifying and other 



