122 The Duration of the Action of Manures . 
check the amount of food consumed in making the dung, but 
equal weights of the manure were taken, the application being 
at the rate of sixteen tons to the acre, and the lots were sampled 
as they were carted out. 
The following Table I. gives a summary of the results : — 
Table I. — Yield from rich and poor dung over a period of 
four years. 
Yield. — Total produce (unmanured plot=100) 
Year of 
application 
1 year old 
residue 
2 year old 
residue 
3 year old 
residue 
Mean of 9 
Mean of 8 
Mean of 7 
Mean of 6 
Dung from roots and hay 
• 
only .... 
13d 
123 
111 
106 
Dung from roots and hay 
with cake 
165 
132 
113 
10S 
In the year of application the cake fed dung had a great 
superiority, it increased the yield above that of the unmanured 
plot by twice the amount of increase produced by the ordinary 
dung, e.g. if the unmanured plot gave 3 qr. of wheat, the plot 
receiving ordinary dung gave 4 qr., and the plot with cake fed 
dung 5 qr. In the following year, however, the superiority 
was much less manifest, the ordinary dung raised the yield by 
one quarter, the cake fed dung by one-third. In the following 
two years, there was no significant difference in the effect of 
the two kinds of dung, the effect of the cake feeding persists 
for two years only, then, though the dung is still producing an 
effect, the poor dung is just as valuable as the rich. To under- 
stand these results let us turn to the analysis of the dung, 
mean values per cent., Table II. : — 
Table II. — Composition of dung. 
Dry 
Matter 
per cent. 
Nitrogen, per cent. 
Total. 
As 
Ammonia 
As 
Amides, 
&c. 
Insoluble 
Dung from roots and 
hay 
26A 
0-530 
0-043 
0-069 
0-418 
Dung from roots and 
hay with cake 
26-6 
0-701 
0-147 
0-118 
0-436 
The cake fed dung naturally contains the most nitrogen, 
0-7 per cent, as against 053 per cent., but the difference is 
almost entirely in the ammonia and other soluble compounds, 
