CARBONATE OF LIME. 109 
The same sun shone on all of Illinois during these 
centuries, the same rains fell, prairie grasses grew 
over most of the land. Where carbonate of lime was 
abundant in the soil humus was created, and the 
land grew black and rich. Where there was de- 
ficiency in carbonate of lime fertility could not 
gather. It is a most significant lesson. 
Carbonate of lime then conserves humus and fer- 
tility in some way. It makes a healthful home for 
the bacteria that help plants. What else does it do? 
Stops Waste of Nitrogen.—Carbonate of lime 
stops waste of nitrogen. Decaying vegetation or 
humus in the soil creates nitric acid; this is readily 
soluble, and unless taken up by plants soon leaches 
away and is gone. Should there be a sufficient sup- 
ply of carbonate of lime present, however, the tiny 
drop of nitric acid seeking to escape touches a par- 
ticle of carbonate of lime, the two unite and form a 
calcium nitrate. This locks up the nitrogen and holds 
it in the soil. It is practically impossible to store fer- 
tility in soils deficient in carbonate of lime. Soils hav- 
ing a large store of carbonate of lime, on the other 
hand, will accumulate nitrogen, and hold it for many 
years, giving it up again when called upon by the 
plants. I have seen astonishing instances of this upon 
Woodland Farm. Certain fields have had on them at 
one day old home sites, where the first settlers built 
their little cabins and had their gardens and cow lots. 
For forty or fifty years these small settlements have 
been swept away, and nothing remains now to tell 
their location excepting the fragments of brick or 
