eir 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) | 10[1] | 0-3/4 | 6
Beans (various manures) | 32[2] | 1-1/4 | 10
Beans (various manures) | 27[3] | 1 | 5
Beans, alternated with wheat | 28[4] | 1 | 10
Clover (various manures) | 29[5] | 3 | 18
Various leguminous plants | 16 | 3 | 18
| | |
Turnips (various manures) | 28[6] | 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
----------------------------------+------------+----------+------------
1. Including one year fallow.

2. Including one year wheat and five years fallow.

3. Including four years fallow.

4. Including two years fallow.

5. Clover, twelve times sown (first in 1848), eight yielding crops, but
four of these very small, one year wheat, five years barley, twelv