“We have seen that Dr. Vœlcker made four separate determinations of the amount of clover-roots left in the soil to the depth of six inches. It may be well to tabulate the figures obtained:
CLOVER-ROOTS, IN SIX INCHES OF SOIL, PER ACRE.
| R/A Air-dry roots, per acre. NR/A Nitrogen in roots, per acre. PhR/A Phosphoric acid in roots, per acre. |
| R/A | NR/A | PhR/A | ||
|---|---|---|---|---|
| 1st Year. | ||||
| No. 1. | Good Clover from brow of the hill | 7705 | 100 | |
| ” 2. | Bad Clover from brow of the hill | 3920 | 31 | |
| 2nd Year. | ||||
| ” 3. | Good Clover from bottom of the field | 7569 | 61 | 27 |
| ” 4. | Thin Clover from brow of the hill | 8064 | 66 | |
| ” 5. | Heavy crop of first-year clover mown twice for hay | 24½ | ||
| ” 6. | Heavy crop of first-year clover mown once for hay, and then for seed | 51½ | ||
| ” 7. | German experiment, 10¼ inches deep | 8921 | 191½ | 74¾ |
I have not much confidence in experiments of this kind. It is so easy to make a little mistake; and when you take only a square foot of land, as was the case with Nos. 5 and 6, the mistake is multiplied by 43,560. Still, I give the table for what it is worth.
Nos. 1 and 2 are from a one-year-old crop of clover. The field was a calcareous clay soil. It was somewhat hilly; or, perhaps, what we here, in Western New York, should call “rolling land.” The soil on the brow of the hill, “was very stony at a depth of four inches, so that it could only with difficulty be excavated to six inches, when the bare limestone-rock made its appearance.”
A square yard was selected on this shallow soil, where the clover was good; and the roots, air-dried, weighed at the rate of 7,705 lbs. per acre, and contained 100 lbs. of nitrogen. A few yards distance, on the same soil, where the clover was bad, the acre of roots contained only 31 lbs. of nitrogen per acre.
So far, so good. We can well understand this result. Chemistry has little to do with it. There was a good stand of clover on the one plot, and a poor one on the other. And the conclusion to be drawn from it is, that it is well worth our while to try to secure a good catch of clover.
“But, suppose,” said the Doctor, “No. 2 had happened to have been pastured by sheep, and No. 1 allowed to go to seed, what magic there would have been in the above figures!”
Nos. 3 and 4 are from the same field, the second year. No. 4 is from a square yard of thin clover on the brow of the hill, and No. 3, from the richer, deeper land towards the bottom of the hill.