this year in the same way. The only difference being that one had
superphosphate and potash, soda, and magnesia, the year before, while
the other had superphosphate alone." It turned out, as you see from the
table, that the potash, etc., only gave half a bushel more wheat per
acre the year it was used, and this year, with 2,000 lbs. of rape-cake
on each plot, there is only a bushel per acre in favor of the potash,
soda, and magnesia.

The next plot, 9_b_, was also unmanured and was passed by my father
without comment. "Ah," said he, on coming to the two next plots, 10_a_
and 10_b_, "this is better, what have you here?" --"_Nothing but
ammonia_," said I, "and I wish you would tell me which is the best of
the two? Last year 10_b_ had a heavy dressing of minerals and
superphosphate with ammonia, and 10_a_ the same quantity of ammonia
alone, without superphosphate or other mineral manures. And this year
both plots have had a dressing of 400 lbs. each of ammonia-salts. Now,
which is the best--the plot that had superphosphate and minerals last
year, or the one without?" --"Well," said he, "I can't see any
difference. Both are good crops."

You will see from the table, that the plot which had the superphosphate,
potash, etc., the year before, gives a peck _less_ wheat this year than
the other plot which had none. Practically, the yield is the same. There
is an increase of 13 bushels of wheat per acre--and this increase _is
clearly due to the ammonia-salts alone_.

The next plot was also a splendid crop.

"What have you here?"

"Superphosphate and ammonia."

This plot (11_a_), turned out 35 bushels per acre. The next plot, with
phosphates and ammonia, was nearly as good. The next plot, with potash,
phosphates, and ammonia, equally good, but no better than 11_a_. There
was little or no benefit from the potash, except a little more _straw_.
The next plot was good and I did not wait for the question, but simply
said, "ammonia," and the next "ammonia," and the next "ammonia."--
Standing still and looking at the wheat, my father asked, "Joe, where
can I get this ammonia?" He had previously been a little skeptical as
to the value of chemistry, and had not a high opinion of "book farmers,"
but that wheat-crop compelled him to admit "that perhaps, after all,
there might be some good in it." At any rate, he wanted to know where
he could get ammonia. And, now, as then, every good farmer asks the same
question: "Where can I get a