“The superphosphate does not seem to have done much good,” said the Deacon; “3½ cwt. per acre gives an increase of less than two bushels per acre. And I suppose it was good superphosphate.”
There need be no doubt on that point. Better superphosphate of lime cannot be made. But you must recollect that this is pure superphosphate made from burnt bones. It contains no ammonia or organic matter. Commercial superphosphates contain more or less ammonia, and had they been used in these experiments, they would have shown a better result than the pure article. They would have done good in proportion to the available nitrogen they contained. If these experiments prove anything, they clearly indicate that superphosphate alone is a very poor manure for either wheat or barley.
The second year, the unmanured plot gave 25¾ bushels per acre. Potash, soda, and magnesia, (or what the Deacon calls “ashes,”) 27⅝ bushels; superphosphate 33½, and “ashes” and superphosphate, nearly 36 bushels per acre.
50 lbs. of ammonia, alone, gives nearly 39 bushels, and ammonia and superphosphate together, 40 bushels.
The superphosphate and “ashes” give a better account of themselves this year; but it is remarkable that the ammonia alone, gives almost as good a crop as the ammonia and superphosphate, and a better crop than the ammonia and “ashes,” or the ammonia, superphosphate, and ashes, together.
The 14 tons farm-yard manure gives over 36 bushels per acre. This plot has now had 28 tons of manure per acre, yet the 50 lbs. of ammonia alone, still gives a better yield than this heavy dressing of manure.
The third season (1854), was quite favorable for the ripening of wheat and barley. The seed on the experimental barley-field, was sown Feb. 24, and the harvest was late; so that the crop had an unusually long season for growth. It was one of the years when even poor land, if clean, gives a good crop. The unmanured plot, it will be seen, yielded over 35 bushels per acre of dressed grain, weighing over 53½ lbs. per bushel. The total weight of grain, was 1,963 lbs. This is over 40 bushels per acre, of 48 lbs. per bushel, which is the standard with us.
The 14 tons of farm-yard manure produce nearly 56½ bushels per acre.
| 50 lbs. of ammonia, on plot 1a. | 47¾ bushels per acre. |
| 100 lbs. of ammonia, on plot 1a.a. | 56⅝ bushels per acre. |
You will see, that though the plot which has received 42 tons of manure per acre, produced a splendid crop; the plot having nothing except 100 lbs. of ammonia per acre, produced a crop equally good. “How much increase do you get from 50 lbs. of ammonia,” asked the Deacon, “and how much from 100 lbs.?”