he _best part_ of the field yielded three tons
(6,720 lbs.) of clover-hay per acre; the whole field averaging 2-1/2
tons (5,600 lbs.) per acre.'

"We are not informed how much land there was of the 'best part,' but
assuming that it was half the field, the poorer part must have yielded
only 4,480 lbs. of hay per acre, or only two-thirds as much as the
other. This shows that there was considerable difference in the quality
or condition of the land.

"After the field was mown for hay, it was divided into two parts: one
part was mown again for hay, August 21st, and yielded about 30 cwt.
(3,360 lbs.) of hay per acre; the other half was allowed to grow six or
seven weeks longer, and was then (October 8th), cut for seed. The yield
was a little over 5-1/2 bushels of seed per acre. Whether the clover
allowed to grow for seed, was on the richer or poorer half of the field,
we are not informed.

"Dr. Voelcker then analyzed the soil. That from the part of the field
mown twice for hay, contained per acre:

First six Second six Third six Total, 18
inches. inches. inches. inches deep.
Phosphoric acid 4,950 2,725 3,575 11,250
Nitrogen 3,350 1,875 1,325 6,550

"The soil _from the part mown once for hay, and then for seed_,
contained per acre:

First six Second six Third six Total, 18
inches. inches. inches. inches deep.
Phosphoric acid 3,975 4,150 3,500 11,625
Nitrogen 4,725 3,350 2,225 10,300

"Dr. Voelcker also ascertained the amount and composition of the
clover-_roots_ growing in the soil on the two parts of the field. On the
_part mown twice for hay_, the roots contained per acre 24-1/2 lbs. of
nitrogen. On the _part mown once for hay, and then for seed_, the roots
contained 51-1/2 lbs. of nitrogen per acre."

"Now," said the Doctor, "these facts are very interesting, _but there is
no sort of evidence tending to show that the clover has anything to do
with increasing or decreasing the quantity of nitrogen or phosphoric
acid found in the soil_."

"There was more clover-roots per acre, where the clover was allowed to
go to seed. But that may be because the soil happened to be richer on
this part of the field. There was, in the first six inches of the soil,
3,350 lbs. of nitrogen per acre, on one-half