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[A] Containing nitrogen .391
Equal to ammonia .475
[B] Including phosphoric acid .264

"I also determined the phosphoric acid in the ash of the clover-roots.
Calculated for the roots in a nearly dry state, the phosphoric acid
amounts to .287 per cent.

"An acre of soil, according to the data, furnished by the six inches on
the spot where the clover was thin, produced the following quantity of
nitrogen:

Ton. Cwts. Lbs.

In the fine soil 1 11 33
In the clover-roots 0 0 66
-- -- --
Total quantity of nitrogen per acre 1 11 99
== == ==

"The organic matter in an acre of this soil, which can not be picked out
by hand, it will be seen, contains an enormous quantity of nitrogen; and
although, probably, the greater part of the roots and other remains from
the clover-crop may not be decomposed so thoroughly as to yield
nitrogenous food to the succeeding wheat-crop, it can scarcely be
doubted that a considerable quantity of nitrogen will become available
by the time the wheat is sown, and that one of the chief reasons why
clover benefits the succeeding wheat-crop, is to be found in the
abundant supply of available nitrogenous food furnished by the decaying
clover-roots and leaves.

CLOVER-SOIL NO. 2, FROM THE BOTTOM OF THE HILL. (GOOD CLOVER.)

"A square yard of the soil from the bottom of the hill, where the clover
was stronger than on the brow of the hill, produced 2 lbs. 8 oz. of
fresh clover-roots; or 1 lb. 11 oz. 47 grains of partially dried roots;
61 lbs. 9 oz. of limestones, and 239.96 lbs. of nearly dry soil.

"The partially dried roots contained:

Moisture 5.06
Organic matter[A] 31.94
Mineral matter 63.00
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100.00
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[A] Containing nitrogen .804

"An acre of this soil, six inches deep, produced 3 tons, 7 cwts. 65 lbs.
of clover-roots, containing 61 lbs. of nitrogen; that is, there was very
nearly the same quantity of roots and nitrogen in them, as that
furnished in the soil from the brow of the hill.

"The roots, moreove