lbs. Peruvian guano | 95 | 10 | 105 | 35 | 3 | 38
12. |75 lbs. sulphate of ammonia | 78 | 10 | 88 | 18 | 3 | 21
13. |200 lbs. Peruvian guano | 88 | 13 | 101 | 28 | 6 | 34
14. |400 lbs. unleached wood-ashes, | | | | | |
| 100 lbs. plaster, and | | | | | |
| 500 lbs. Peruvian guano | 111 | 14 | 125 | 51 | 7 | 58
-----+----------------------------------+-----+----+-----+----+----+----

"The superphosphate of lime was made on purpose for these experiments,
and was a pure mineral manure of superior quality, made from calcined
bones; it cost about 2-1/2 cents per pound. The sulphate of ammonia was
a good, commercial article, obtained from London, at a cost of about
seven cents per pound. The ashes were made from beech and hard maple
(_Acer saccharinum_) wood, and were sifted through a fine sieve before
being weighed. The guano was the best Peruvian, costing about three
cents per pound. It was crushed and sifted before using. In sowing the
ashes on plot 7, an error occurred in their application, and for the
purpose of checking the result, it was deemed advisable to repeat the
experiment on plot 10.

"On plot 5, with 300 lbs. of superphosphate of lime per acre, the plants
came up first, and exhibited a healthy, dark-green appearance, which
they retained for some time. This result was not anticipated, though it
is well known that superphosphate of lime has the effect of stimulating
the germination of turnip-seed, and the early growth of the plants to an
astonishing degree; yet, as it has no such effect on wheat, it appeared
probable that it would not produce this effect on Indian corn, which, in
chemical composition, is very similar to wheat. The result shows how
uncertain are all speculations in regard to the manurial requirements of
plants. This immediate effect of superphosphate of lime on corn was so
marked, that the men (who were, at the time of planting, somewhat
inclined to be skeptical, in regard to the value of such small doses of
manure), declared that 'superphosphate beats all creation for corn.' The
difference in favor of superphosphate, at the time of hoeing, was very
perceptible, even at some distance.

"Although every precaution was taken that was deemed necessary, to
prevent the manures from mixing in the hill, or from injuring the seed,
yet, it was found, that those plots dressed with ashes and guan