o, or
with ashes and sulphate of ammonia, were injured to some extent. Shortly
after the corn was planted, heavy rain set in, and washed the sulphate
of ammonia and guano, down into the ashes, and mutual decomposition took
place, with more or less loss of ammonia. In addition to this loss of
ammonia, these manures came up to the surface of the ground in the form
of an excrescence, so hard that the plants could with difficulty
penetrate through it.

"It will be seen, by examining the table, that although the
superphosphate of lime had a good effect during the early stages of the
growth of the plants, yet the increase of ears of corn in the end did
not come up to these early indications. On plot 5, with 300 lbs. of
superphosphate of lime per acre, the yield is precisely the same as on
plot 2, with 100 lbs. of plaster (_sulphate of lime_), per acre. Now,
superphosphate of lime is composed necessarily of soluble phosphate of
lime and plaster, or sulphate of lime, formed from a combination of the
sulphuric acid, employed in the manufacture of superphosphate, with the
lime of the bones. In the 300 lbs. of superphosphate of lime, sown on
plot 5, there would be about 100 lbs. of plaster; and as the effect of
this dressing is no greater than was obtained from the 100 lbs. of
plaster, sown on plot 2, it follows, that the good effect of the
superphosphate of lime was due to the plaster that it contained.

"Again, on plot 4, with 150 lbs. of sulphate of ammonia per acre, we
have 90 bushels of ears of sound corn, and 15 bushels of ears of soft
corn, ('nubbins,') per acre; or a total increase over the plot without
manure, of 38 bushels. Now, the sulphate of ammonia contains no
phosphate of lime, and the fact that such a manure gives a considerable
increase of crop, confirms the conclusion we have arrived at, from a
comparison of the results on plots 2 and 5; that the increase from the
superphosphate of lime, is not due to the phosphate of lime which it
contains, unless we are to conclude that the sulphate of ammonia
rendered the phosphate of lime in the soil more readily soluble, and
thus furnished an increased quantity in an available form for
assimilation by the plants--a conclusion, which the results with
superphosphate alone, on plot 5, and with superphosphate and sulphate of
ammonia, combined, on plot 6, do not sustain.

"On plot 12, half the quantity of sulphate of ammonia, was used as on
plot 4, and the increase is a little