LIMING OF SOILS FROM A PHYSIOLOGICAL STANDPOINT. 35 
serve for the determination of the available nutrients. The results 
are calculated for the whole soil. Thus, the easily available amounts 
of lime and magnesia will be at least approximately obtained. It will 
be impossible to obtain numbers that are constants of availability, 
since the roots of different species have also different powers of absorp- 
tion. Nilsen and Eggertz* found that a very fertile soil became, after 
extraction with 2 per cent hydrochloric acid, sterile for barley, but 
not yet sterile for oats. A treatment of the soil with acid of double 
the strength was necessary to render it sterile for oats. 
As regards the separation of the soil into a finer and coarser portion, 
it must be mentioned that experiments have proved that the finer 
particles come principally into consideration in regard to fertility. 
Larger particles may be attacked along their surface only, but will 
not be dissolved by one year’s growth of vegetation. 
Should the analyses not show, as above assumed, an excess of 
magnesia, but, on the contrary, an amount of available magnesia far 
below that of lime in the fine particles of the soil, an addition of finely 
ground unburned magnesite or unburned pulverized magnesian lime- 
stone should be made. The application of artificially precipitated basic 
magnesium carbonate or burned magnesia can not be recommended, 
since they are not only too expensive for the purposes of agriculture, 
but also very injurious, being easily absorbed, owing to their very 
fine pulverulent condition. 
The above-mentioned experiments of Ulbricht furnish abundant 
proof of the considerable differences in the action of powdered 
magnesite and precipitated magnesium carbonate. 
Finally, the analysis may show a lack of lime as well as of magnesia. 
Soils occur, indeed, with less than 0.1 per cent of these nutrients. 
Manuring with a mixture of marl and magnesite or with pulverized 
magnesian limestone containing less than 40 per cent magnesia is then 
in order. 
If the ratio of lime and magnesia in the soils is judicially regulated, 
great benefit to agriculture will result and an essential step forward 
be made. 
1Landw. Vers. Stat., 1891, Vol. XX XVIII, p. 344. 
