Note 81 — Chapter VIII · ABSORPTION BY SOILS.
Reading edition
An extreme case is worth citing in this connection. Mr. W. H. Heileman in studying the influence of various kinds of alkali upon plant growth, added from 3-4 per cent. of sodium carbonate to soils known to be otherwise free from alkali. Wheat seedlings grown in the soils so treated showed no ill effects from the added salt. When distilled water was percolated slowly through the soils, or shaken up with them, the resulting solution contained the merest traces of the alkali.
The ordinary method of determining the lime requirement of a soil by adding lime water until the solution shows an alkaline reaction, is another obvious absorption phenomenon, and is not dependent, as popularly supposed, upon the presence of acids in the soil. Soils which by no possibility could contain any free acid, frequently absorb very large amounts of lime in this manner.