The Duration of the Action of Manures. 121 
Year 
Plot A Plot B 
| 
Plot C 
Plot D 
Plot E 
1904 
Manure 
— 
— 
— 
No manure 
Check 
1905 
No manure 
1 year old resi- 
due 
Manure 
— 
— 
No manure 
Check 
1906 
No manure 
2 year old resi- 
due 
No manure 
1 year old resi- 
due 
Manure 
— 
No manure 
Check 
1907 
No manure 
3 year old resi- 
due 
No manure 
2 year old resi- 
due 
No manure 
1 year old resi- 
due 
Manure 
v o manure 
Check 
1908 
Manure 
No manure 
3 year old resi- 
due 
No manure 
2 year old resi- 
due 
No manure 
1 year old resi- 
due 
No manure 
Check 
1909 
No manure 
1 year old resi- 
due 
Manure 
No manure 
3 year old resi- 
due 
No manure 
2 year old resi- 
due 
No manure 
Check 
Ac. 
Ac. 
&c. 
Ac. 
Ac. 
&c. 
mammal series there was one check plot nnmanured ; these 
were arranged diagonally across the field and the mean of all 
the five was used for comparison in the case of nitrogenous 
manures, the mean of three is the standard for the phosphatic 
plots. It will not be necessary here to give the details of all 
the crops (tbe actual amounts of manure applied and the yields 
are set out in the Guide to the Rothamsted Experiments and 
in the Annual Report from year to year) ; to bring them into 
comparison the mean yield (total produce, grain and straw 
or roots and leaves) on the check plots was each year taken as 
100, and the other yields calculated to that standard. It will 
be convenient to consider separately the results obtained : 
(1) from dung, (2) from other nitrogenous fertilisers, (3) from 
phosphatic fertilisers. 
1. Residual values of rich and poor dung. 
The dung for the experiment was made afresh each year ; 
a couple of bullocks were fed under cover on hay and roots 
alone, another pair alongside had the same roots and hay, the 
same straw litter, but in addition a good ration of 5-8 lb. of 
cake per diem. The two lots of dung were either taken 
straight from the stalls on to the land or made up into heaps 
side by side and treated exactly alike until they were carted 
out to the land and ploughed in. No attempt was made to 
