| No manure | 119 bushels per acre. |
| 300 lbs. Peruvian guano | 205 bushels per acre. |
The guano cost, here, about 3 cents a lb., and consequently nine dollars’ worth of guano gave 84 bushels of potatoes. The potatoes were all sound and good, but where the guano was used, they were larger, with scarcely a small one amongst them.
In 1857, I made the following experiments on potatoes, in the same field on which the preceding experiment was made in 1852.
In this case, as before, the land was a two-year-old clover-sod. It was plowed about the first of May, and harrowed until it was in a good mellow condition. The potatoes were planted in hills 3½ feet apart each way. The following table shows the manures used and the yield of potatoes per acre.
Experiments on Potatoes at Moreton Farm.
| Y/A Yield of Potatoes per acre, in bushels. I/A Increase of Potatoes per acre, in bushels, caused by manure. |
| P l o t. | Description of Manures used, and quantities Applied per acre. | Y/A | I/A |
|---|---|---|---|
| 1. | No manure | 95 | |
| 2. | 150 lbs. sulphate of ammonia | 140 | 45 |
| 3. | 300 lbs. superphosphate of lime | 132 | 37 |
| 4. | 150 lbs. sulphate of ammonia, and 300 lbs. superphosphate of lime | 179 | 84 |
| 5. | 400 lbs. of unleached wood-ashes | 100 | 5 |
| 6. | 100 lbs. plaster, (gypsum, or sulphate of lime,) | 101 | 6 |
| 7. | 400 lbs. unleached wood-ashes and 100 lbs. plaster | 110 | 15 |
| 8. | 400 lbs. unleached wood-ashes, 150 lbs. sulphate of ammonia and 100 lbs. plaster | 109 | 14 |
| 9. | 300 lbs. superphosphate of lime, 150 lbs. sulphate of ammonia and 400 lbs. unleached wood-ashes | 138 | 43 |
The superphosphate of lime was made expressly for experimental purposes, from calcined bones, ground fine, and mixed with sulphuric acid in the proper proportions to convert all the phosphate of lime of the bones into the soluble superphosphate. It was a purely mineral article, free from ammonia and other organic matter. It cost about two and a half cents per pound.
The manures were deposited in the hill, covered with an inch or two of soil, and the seed then planted on the top. Where superphosphate of lime or sulphate of ammonia was used in conjunction with ashes, the ashes were first deposited in the hill and covered with a little soil, and then the superphosphate or sulphate of ammonia placed on the top and covered with soil before the seed was planted. Notwithstanding this precaution, the rain washed the sulphate of ammonia into the ashes, and decomposition, with loss of ammonia, was the result. This will account for the less yield on plot 8 than on plot 2. It would have been better to have sown the ashes broadcast, but some previous experiments with Peruvian guano on potatoes indicated that it was best to apply guano in the hill, carefully covering it with soil to prevent it injuring the seed, than to sow it broadcast. It was for this reason, and for the greater convenience in sowing, that the manures were applied in the hill.