II. Plot 2 B; Receiving Dung (14 Tons, Containing 200 Lb. Nitrogen A Year)

lb. per Acre.

Nitrogen present in 1865 (.1752 per cent)..............

4,343

Nitrogen supplied in manure, 1865-93

5,600

Nitrogen supplied in rain, 1865-93..........

140

Nitrogen supplied in seed, 1865-93

56

Total expected in 1893

10,139

Nitrogen removed in crops, 1865-93 ...

1,484

Nitrogen found in soil, 1893 (2132 per cent) ...

4,976

Total accounted for in 1893

6,460

Leaving nitrogen unaccounted for..........

3,679

10,139

It would be difficult to find clearer examples of overdosing a soil with food it did not require. In one case (Plot 7), leaving out the unavoidable supplies from the rain and seed, 2408 lb. of nitrogen were given to a soil already containing 3034 lb. Almost twice as much as the crop needed! In the other case 5600 lb. nitrogen were given to a soil still richer in the same food (4343 lb. per acre). But in this case, the greater the overdose the smaller the quantity removed by nearly 500 lb.

That the loss of nitrogen was due mainly to overdosing seems to be still further proved by the experiment on the unmanured plot, the figures for which are as follows: -

Plot 3: Unmanured, 1865 To 1893

lb per Acre,

Nitrogen originally present in 1865 (.1050 per cent), top 9 in.

2722

Nitrogen supplied in manure, 1865-93..............

0

Nitrogen supplied in rain, 1865-93...........

140

Nitrogen supplied in seed, 1865-93 ...

56

Total expected in 1893

2918

Nitrogen removed in crops, 1865-93............

476

Nitrogen found in soil, 1893 (.0940 per cent) ......

2437

Total nitrogen accounted for, 1893

2913

Nitrogen not accounted for................

5

2918

It would appear from these experiments that it is just as unwise to give plants more food than they require in a given time as it is to gorge animals with a certain diet. The system cannot absorb it, and the body suffers in health in consequence. It would be interesting to have had some information as to the cultural details carried out at Rothamsted, the depth of culture, distance apart, and the yield per acre.