9,867 lbs.: or, in round numbers, 3 tons and 12-1/2
cwts. of nitrogen per acre; equal to 4 tons 8 cwts. of ammonia.

"This is a very much larger amount of nitrogen than occurred in the
other soil, and shows plainly that the total amount of nitrogen
accumulates especially in the surface-soil, when clover is grown for
seed; thus explaining intelligibly, as it appears to me, why wheat, as
stated by many practical men, succeeds better on land where clover is
grown for seed, than where it is mown for hay.

"All the three layers of the soil, after clover-seed, are richer in
nitrogen than the same sections of the soil where the clover was twice
mown, as will be seen by the following comparative statement of results:

--------------+--------------------------+--------------------------
| I. | II.
| Clover-Soil twice | Clover-Soil once mown
| mown. | and then left for seed.
+--------+--------+--------+--------+--------+--------
| | | | | |
| Upper | Second | Third | Upper | Next | Lowest
|6 inches|6 inches|6 inches|6 inches|6 inches|6 inches
--------------+--------+--------+--------+--------+--------+--------
Percentage of | | | | | |
nitrogen in | .168 | .092 | .064 | .189 | .134 | .089
dried soil | | | | | |
Equal to | | | | | |
ammonia | .198 | .112 | .078 | .229 | .162 | .108
--------------+--------+--------+--------+--------+--------+--------

"This difference in the amount of accumulated nitrogen in clover-land,
appears still more strikingly on comparing the total amounts of nitrogen
per acre in the different sections of the two portions of the 11-acre
field.

Percentage of Nitrogen Per Acre.

First six Second Third six
inches. six inches. inches.
Lbs. Lbs. Lbs.
I. In soil, clover twice }
mown[A] } 3,350 1,875 1,325
II. In soil, clover once }
mown and seeded }
afterwards[B] } 4,725 3,350 2,225
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