LIMING OF SOILS FROM A PHYSIOLOGICAL STANDPOINT. 15 
yield the means to properly estimate the quality of the soil. Such an 
analysis must not only regard the absolute quantities of phosphoric 
acid, sulphuric acid, potassa, lime, magnesia, iron, and nitrogen com- 
pounds, but must also consider the fineness or coarseness of the divi- 
sion of the nutritive materials and their solubility in dilute organic 
acids. But the writer must add that there is another important factor 
in the valuation of soils, and that is the ratio of the easily assimilable 
amounts of lime and magnesia in the finer particles. Many attacks 
have been made upon the use of analyses of soil for purposes of valua- 
tion, but this opposition can only relate to certain analyses, such as 
made in.the old method of treating the soil with concentrated hydro- 
chlorie acid.’ Such analyses will not show exactly the amount of 
nutrients available for the next crop, but mainly indicate the whole 
amount of nutrients available within a longer period. 
Every farmer ought to know the ratio of the easily assimilable por- 
tion of lime to magnesia in his soil, as with such knowledge he can tell 
when liming is needed and if magnesian limestone will prove injurious. 
Soils with much magnesia are more to be feared than those with too 
little. There may be soils with but little available magnesium car- 
bonate which still produce excellent crops, for in this connection it 
must be remembered that water containing carbonic acid can dissolve 
more magnesium carbonate than calcium carbonate. Treadwell and 
Reuter’ found that 1 liter of water will hold 0.385 gram calcium 
bicarboriate in solution, while it will contain 1.954 grams of mag- 
nesium bicarbonate, besides 0.715 gram neutral magnesium carbonate. 
When it is further remembered that magnesia is more movable in 
plants than lime, and that therefore one and the same molecule of mag- 
nesia can serve repeatedly as a carrier of phosphoric acid for the 
formation of nucleo-proteids and lecithin, it will not appear strange 
that a soil can still produce certain crops when the content of mag- 
nesia is very much smaller than that of the lime. This is especially 
true when such plants are grown as are capable of excluding any 
absorbed excess of lime from further physiological influence by trans- 
forming it into the nearly insoluble calcium oxalate. The situation is 
far different, however, on a soil that contains a considerable excess of 
magnesia over lime, and here a proper correction is an absolute 
necessity. 
‘Compare also the interesting results of Thoms. Agric. Centralbl., 1898, p. 155, 
whose theoretical inferences from soil analyses were in full accord with the practical 
observation on the fertility of various domains. 
* Zeitschr. f. Anorg. Chem., 1898, Vol. X VII, p. 170. 
