Experimental Crops at Rothamsted. 
that between the removal of tlie crops and the date of sampling 
the soils, in all nearly an inch of rain had fallen, perhaps affect- 
ing somewhat the actual percentages, but the relative amounts 
probably but little. 
The first point to remark is, that the first 9 inches of soil of 
both the heavily manured, and more or less heavily cropped, 
plots contained a higher percentage of moisture than that of 
the unmanured and lightly cropped plot. But from that point 
■downwards to a depth of 54 inches, and doubtless further still, 
the manured and more heavily cropped soils contained much less 
moisture than the unmanured ; and the most heavily cropped 
soil, that of Plot 14, manured with mineral manure and nitrate of 
soda, contained considerably less than that of Plot 9, manured with 
mineral manure and ammonia-salts. And whilst at a depth of 
from 45 to 54 inches the unmanured soil contained 25 per cent, 
of moisture, that receiving mineral manure and ammonia-salts 
contained only 21 "34 per cent. ; and that receiving mineral 
manure and nitrate of soda only 18 per cent., or scarcely fths as 
much as the unmanured soil at the same depth. To sum up 
the results, there is an average amount of moisture down to the 
depth of 54 inches, of 19|- per cent, on the plot without manure, 
of only 16J per cent, on the plot manured with mineral manure 
and ammonia-salts, and of scarcely 15 J per cent, on that manured 
with mineral manure and nitrate of soda, or only about iths as 
much on the latter as on the unmanured plot. 
The subsoil of this meadow land is a reddish yellow clay, 
interspersed with grev veins, and the specific gravity increases 
by about one-half from the surface down to the greatest depth 
taken. For our present purpose it will be a sufficiently near 
approximation to the truth to assume that down to the depth 
of 54 inches, the soil (exclusive of stones) weighed an average of 
1,000,000 lbs. per acre for every 3 inches of depth, or an aggre- 
gate of 18,000,000 lbs. per acre to the depth of 54 inches. 
Adopting this estimate, and the percentages of moisture given 
in Table III., it results that down to the depth of 54 inches, or 
4 feet 6 inches, the unmanured soil retained 1546, the soil of 
Plot 9, 1346, and that of Plot 14, 1221 tons of water. That is 
to say, to the depth of 4 feet 6 inches, the soil of Plot 9, manured 
with mineral manure and ammonia-salts, contained 200 tons, 
and that of Plot 14, manured with mineral manure and nitrate 
•of soda, 325 tons less water per acre than that of the unma- 
nured soil to the same depth ; whilst, from the great difference 
in the percentage at the lowest depths taken in the three cases, 
there can be no doubt that the difference extended considerably 
•deeper still. 
Here, then, we have evidence of the source whence the ma- 
H 2 
