Proceedings of Seventeenth Normal Institute 131 



Acid constituents in the soil may be in both the soluble and 

 insoluble condition; the former would appear freely in the soil 

 water. Such a condition is very unusual, as the soil solution is 

 usually neutral or alkaline. Nearly all soils have a large excess 

 of silicic acid, which is very insoluble either in silicate compounds 

 or in the form of quartz grains. 



Soluble acid materials produce a positive acid condition. The 

 insoluble forms are termed negative acidity and may be called 

 lack of basicity. In either case lime and other basic elements 

 will be actively taken up. 



FORMS OF LIME 



Kesults on the Cornell University Farm and on plots at Virgil, 

 both of which have continued for only two or three years, and 

 from which no decisive conclusions can be drawn, have shown 

 somewhat better results from caustic than from carbonate lime. 



Magnesium lime has given results inferior to calcium lime. 



DISAPPEARANCE OF CAUSTIC LIME AND OF CALCIUM AND MAGNE- 

 SIUM LIME CARBONATE IN THE SOIL 



Bulletin 107 of the Tennessee Station, recently published, 

 gives the most definite data available on many of these points. 

 Tests in carbonated water and in carbonated wet soil showed that 

 both calcium and magnesium oxide were completely carbonated 

 in four hours. The indication, therefore, is that caustic lime does 

 not remain in the normal soil as such for more than a few hours 

 or days at the most, and any difference in the effect of caustic and 

 carbonate lime on the soil after that date must be due to some 

 other factor than persistent causticity. 



Magnesium carbonate is found to rapidly disappear from the 

 soil due to the union of the magnesium oxide with silica to 

 form the silicate of magnesium, which is only one-third to one- 

 fourth as soluble as dolomite. This change occurs to a large 

 extent in a few weeks. As much as fourteen tons were found to 

 disappear in an acre seven inches of very acid soil. Calcium 

 carbonate is very much less affected in the same manner. Injury 

 from the use of magTiesium lime is probably due to the silicate 

 compounds and not to its persistence either as caustic magnesia 

 or as magnesium carbonate, which latter is only half as soluble as 

 calcium carbonate. 



