374 
AGRICULTURE. 
Stances are known of land producing a succession 
of good crops for many years, without fallowing or 
manuring. On the summit of Baden Hill, in an ex- 
posed and elevated situation, I have seen a luxuri- 
ant crop of barley growing on land that had borne 
a succession of 20 preceding crops without manu- 
ring."* 
Such are the views which have generally pre- 
vailed of late on the subject of soils, and the ef- 
fects of a due admixture of the various ingredients 
composing them. Some writers, however, main- 
tain, that the best possible mixtures do not directly 
give fertiUty, but that this depends on the salts or 
soluble organic matter contained in them ; and that 
a due proportion of sand, clay, and lime forming 
the soil, favours vegetation, by allowing the air, 
moisture, and lime rapidly to dissolve organic mat- 
ter, and yield it readily to the roots of plants. This 
decomposed organic matter is called geine by Eer- 
zelius, humin by Sprengel and other chemists. It 
is, however, unimportant in what manner a due 
proportion of the above elements acts in producing 
fertihty, Wie fact itself being the chief point to which 
we wish to call attention. 
We have stated that Professor Hitchcock has 
discovered the singular fact, that not one in thirty 
of the soils of Massachusetts contain any calcare- 
ous matter. This accounts for the great benefit 
generally produced by the application of lime to 
her soils ; for analysis shows that lime forms one 
of the constituent parts of vegetables. One of the 
most important benefits ever conferred by geology 
upon agriculture, is the late discovery of the im- 
mense advantages resulting from the application 
of the green sand marl of New-Jersey to sandy 
soils. We cannot present this matter in a better 
light than by quoting some passages from a late 
* BakewelFs Geology, p. 390. 
