Reference has been so repeatedly made in the preceding pages to the Rothamsted experiments on manures, that it may form a fitting conclusion to the present treatise to give a short account of these famous experiments.
In describing these experiments, the author has remarked elsewhere[256] "that, in respect of their wide scope, dealing as they have done with almost every department of farming, the elaborate care and accuracy with which they have been carried out, the length of time they have been in progress, and, lastly, in respect of the important bearing their results have had on agricultural practice, these famous experiments may be justly described as unrivalled by any other similar ones."
Started on a small scale in 1837 by Sir John (then Mr) Lawes, they were placed on a systematic basis in 1843, in which year Sir John Lawes associated with himself Sir (then Dr) J. Henry Gilbert. They have thus been in progress for a period of fifty years—a fact which was celebrated a few months ago by the presentation of numerous congratulatory addresses from various learned and agricultural societies to the distinguished investigators, and the erection of a memorial granite slab at Rothamsted. What increases the feeling of gratitude due to Sir John Lawes by the agricultural community, is the fact that the entire expense of conducting these experiments has been borne by himself, and he has further most generously handed over to the nation a large sum of money and a certain area of land for carrying them on in perpetuity.
Nature of Experiments on Crops and Manures.
The earliest systematic experiments were on turnips, and since then almost every common crop has been experimented on. Table I. (p. 562) is a list of the different experiments, with their duration, area, and number of plots.
Soil of Rothamsted.
Before describing the more striking results of these experiments, it may be advisable to say that the elevation of the land at Rothamsted is about 400 feet above sea-level; that the average rainfall is about 28 inches per annum; and that the surface-soil is a heavy loam, and the subsoil a stiff clay, resting on chalk.
TABLE I.—List of Rothamsted Field Experiments.
| Crops. | Duration. | Area. | Plots. |
| Years. | Acres. | ||
| Wheat (various manures) | 50 | 11 | 34 (or 37) |
| Wheat alternated with fallow | 42 | 1 | 2 |
| Wheat (varieties) | 15 | 4-8 | about 20 |
| Barley (various manures) | 42 | 4-1/4 | 29 |
| Oats (various manures) | 101 | 0-3/4 | 6 |
| Beans (various manures) | 322 | 1-1/4 | 10 |
| Beans (various manures) | 273 | 1 | 5 |
| Beans, alternated with wheat | 284 | 1 | 10 |
| Clover (various manures) | 295 | 3 | 18 |
| Various leguminous plants | 15 | 3 | 18 |
| Turnips (various manures) | 286 | 8 | 40 |
| Sugar-beet (various manures) | 5 | 8 | 41 |
| Mangel-wurzel (various manures) | 18 | 8 | 41 |
| Total root crops | 51 | ||
| Potatoes (various manures) | 18 | 2 | 10 |
| Rotation (various manures) | 46 | 3 | 12 |
| Permanent grass (various manures) | 38 | 7 | 22 |
| 1Including one year fallow. | |||
| 2Including one year wheat and five years fallow. | |||
| 3Including four years fallow. | |||
| 4Including two years fallow. | |||
| 5Clover, twelve times sown (first in 1848), eight yielding crops, but four of these very small, one year wheat, five years barley, twelve years fallow. | |||
| 6Including barley without manure three years (eleventh, twelfth, and thirteenth seasons). | |||
Wheat Experiments.