Field Experiments on Potatoes. 
411 
weighed. There were no diseased potatoes in the produce of 
the different plots, and the few frosted potatoes found in the 
various lots were weighed with the pig-potatoes. 
The preceding tabular statement (Table XI.) embodies the 
details of Mr. Wall's potato experiments. 
It will be noticed that three plots were left unmanured — 1 at 
each end of the 10 experimental plots, and the third occupying 
a more central position. 
The crop on the three unmanured plots differed but little in 
weight, showing that the field on which the experiments Avere 
tried was uniform in character and productive powers. The 
average produce of the three unmanured plots, calculated per acre, 
amounts to 6 tons 11 cwts. and 44 lbs. 
The unmanured crop thus weighed more in " the Lizards " 
potato experiments than the natural produce of any of the 
preceding field-trials. 
6i- tons to the acre is not a bad crop of potatoes. The land 
appears to have been in a better agricultural condition than the 
soils on which the preceding experiments were tried ; and this, 
no doubt, was the reason that on the clay-loam the various 
manures produced comparatively much less increase than they 
did on the light sandy soils of the preceding experimental 
fields. 
The following table shows the increase and decrease of the 
produce of each plot over the average yield of the unmanured 
plots, and the increase or decrease percentage of each plot : — • 
Table XIT. — Showing tlie Increase and Decrease of the Produce of each 
Manured Plot over the average yield of the Unmanured Plots, calculated 
per Acre, and Increase or Decrease per Cent. 
Plots. 
Name of Manure. 
Increase. 
Decrease, l Increase. Decrease. 
I Mineral Superphosphate . 
Crude Potash-salts .. 
and 
Sulphate of Ammonia , 
Rotten Dung 
(Mineral Superphosphate , 
and 
Crude Potash-salts .. 
i Mineral Superphosphate 
Crude Potash-salts . . 
and 
Nitrate of Soda 
Peruvian Guano 
j Mineral Superphosphate , 
< and 
(Common Salt 
Rotten Dung 
Tons cwts. lbs. \ cwts. lbs. ' Per Cant. Per Cent. 
1 12 15 
2 17 90 
1 9 60 
1 17 65 
1 3 88 
3 13 88 
7 17 
24-45 
44-12 
22-47 
28-60 
18-10 
56-15 
5-44 
VOL. VI. — S.S. 
2 F 
