| Bushels per acre. | |
|---|---|
| No manure | 221 |
| 4 cwt. mineral superphosphate | 225 |
| 4 cwt. mineral superphosphate and | 240 |
| 4 cwt. of muriate of potash | |
| 15½ tons farm-yard manure | 293 |
“That does not say much for potash and superphosphate,” said the Deacon. “The superphosphate only produced four bushels more than the no manure, and the potash and superphosphate only fifteen bushels more than the superphosphate alone.”
It may be worth while mentioning that one of the experimental plots this year was on a head-land, “where the cattle frequently stand for shelter.” This plot was dressed with only eight and a half tons of manure, and the crop was over 427 bushels per acre, while a plot alongside, without manure, produced only 163 bushels per acre.
“That shows the importance,” said the Deacon, “of planting potatoes on rich land, rather than to plant on poor land and try to make it rich by applying manure directly to the crop.”
The following are some of the results in 1868:
| Bushels per acre. | ||
|---|---|---|
| 1. | No manure | 232 |
| 2. | 4 cwt. superphosphate | 340 |
| 2 cwt. muriate of potash | ||
| 2 cwt. sulphate of ammonia | ||
| 3. | 20 tons farm-yard manure | 342 |
| 4. | 4 cwt. superphosphate | 274 |
| 4 cwt. muriate of potash |
“Here again,” said the Doctor, “superphosphate and potash alone give an increase of only forty-two bushels per acre, while on plot 2, where two hundred weight of muriate of potash is substituted by two hundred weight of sulphate of ammonia, the increase is 108 bushels per acre. It certainly looks as though a manure for potatoes, so far as yield is concerned, should be rich in available nitrogen.”
The following are some of the results in 1869:
| Bushels per acre. | ||
|---|---|---|
| 1. | No manure | 176 |
| 2. | 4 cwt. superphosphate | 306 |
| ¾ cwt. sulphate of magnesia | ||
| 2 cwt. muriate of potash | ||
| 2 cwt. sulphate of ammonia | ||
| 3. | 4 cwt. superphosphate | 189 |
| 4. | 4 cwt. superphosphate | 201 |
| 2 cwt. sulphate of ammonia | ||
| 5. | 4 cwt. superphosphate | 340 |
| 2 cwt. muriate of potash | ||
| 2 cwt. sulphate of ammonia. | ||
| 6. | 4 cwt. superphosphate | 249 |
| 2 cwt. muriate of potash | ||
“This is a very interesting experiment,” said the Doctor. “Superphosphate alone gives an increase of thirteen bushels. Superphosphate and potash an increase of seventy-three bushels. The potash, therefore, gives an increase of sixty bushels. Superphosphate and ammonia give twelve bushels more than superphosphate alone, and the reason it does not produce a better crop is owing to a deficiency of potash. When this is supplied the ammonia gives an increase (plots 5 and 6) of ninety-one bushels per acre.”