Field Experiments on Potatoes. 
405 
The produce on the 3 unmanured plots, it will be seen, 
varied to some extent, though not more than may be expected in 
a dry season. 
On an average the crop on the unmanured plots weighed 
per acre, 3 tons 5 cwts. 2 qrs. and 11 lbs. 
The small crop per acre shows that the land naturally was not 
too rich, and therefore well adapted for experimental purposes. 
In the next table the increase on each plot over the average 
produce of clean potatoes from the unmanured plots is given. 
Table VIII. — Showing the Increase jier Acre on each Experimental Plot over 
the Average Produce from the Unmanured Land. 
Plots. 
Name of Manure. 
i Mineral Superphosphate 
Crude Potash-salts 
and 
Sulphate of Ammonia .. 
JJotten Dung 
{Mineral Superphosphate 
aod 
Crude Potash-salts 
1 Mineral Superphosphate 
Crude Potash-salts 
and 
Nitrate of Soda .. .. 
Peruvian Guano .. 
(Mineral Superphosphate 
\ and 
(Common Salt 
Kotten Dung 
Increase per Acre. 
Tons cwts. qrs. lbs. 
4 18 0 17 
4 6 0 21 
3 19 1 17 
1 4 
0 9 
1 17 
1 17 
5 14 1 17 
Average produce per acre of Plots 1, 5, 10 
3 tons 5 cwts. 2 qrs. 11 lbs. 
A glance at the preceding tabular statement of results, amongst 
other particulars, shows : — ■ 
1. That the mixture of 4 cwts. of mineral superphosphate, 
2 cwts. of crude potash-salts, and 2 cwts. of sulphate of ammonia 
is an excellent manure for potatoes on light soils. 
This mixture yielded an increase of nearly 5 tons over the 
average yield of the unmanured land, and as the average produce 
of the two plots, manured with rotten dung at the rate of 20 tons 
to the acre, amounts to 5 tons 1 qr. and 5 lbs. calculated per 
acre, the artificial manure employed on Plot 2 had as great an 
effect on the potato-crop as a full dressing of rotten dung. 
2. That the omission of sulphate of ammonia from the mixture 
used on Plot 1 caused a diminution in the increase of nearly 
1 ton per acre. 
3. That the addition of nitrate of soda to superphosphate and 
potash-salts did not answer quite so well as the addition of an 
