194 Causes of Fertility or Barrenness of Soils. 
Analysis of Barren and Fertile Sands. 
Barren. 
Fertile 
for Lucerne, 
Sainfoin, 
and Lupins. 
Fertile 
for Beans and 
Peas. 
SilipT 
aft . f\f\Ci 
O 4 . 7nA 
y4 / uu 
on . o-m 
1 . iif\r\ 
I ouu 
o • 1 c\R 
z luo 
o . Ann 
o - (\f^f\ 
Z UUU 
o yol 
1 uuu 
Trace 
Trace 
•730 
Trace 1 
Trace / 
•100 
•076 
Phosphoric Acid 
Trace 
Trace 
•367 
Trace 
Trace 
Trace 
Oxide of Manganese .. 
None 
None 
-960 
None 
None 
•010 
1-499 
•500 
1^040 
100-000 
99-900 
99-990 
The above analyses of sandy soils are instructive. The first, 
that of the barren sand, contains, besides insoluble matter, only 
\ per cent, of alumina, a quantity quite insufficient to have any 
mechanical influence ; 2 per cent, of iron, probably as peroxide ; 
\\ per cent, of humus, and only traces of the most important 
substances. The second soil is designated as sandy loam, said 
to produce luxuriant crops of lucerne, sainfoin, and lupins ; facts 
which the chemist could hardly have anticipated, as it only differs 
from No. 1 in containing 1 per cent, of lime and 1 per cent, more 
alumina, and a small portion of alkalies. The third analysis is 
of a soil growing fine pulse crops ; and here we have indications 
of more fertility in the presence of appreciable quantities of phos- 
phoric acid and magnesia, though there is nothing which would 
lead us to expect the soil anything but poor. These analyses 
were made by Sprengel, and are not of very recent date, conse- 
quently we do not feel such confidence in their accuracy as if 
conducted on the modern system ; indeed little reliance is to be 
placed upon any old analysis of soils. The fertilising materials 
are often in such minute quantities, yet sufficient for the require- 
ments of the crop, that they totally escape detection, or can only 
be represented by a trace ; and it may be the variation in the 
amount of the latter which causes the remarkable difference of 
fertility in the two first soils. The limit of variation in the best 
conducted analysis is often equal for some substances (phosphoric 
acid for example) to the total quantity in the body analysed, 
consequently in such cases little reliance can be placed on the 
result. The reagents employed are not always perfectly pure ; 
