406 
Field Experiments on Potatoes. 
equal weight of sulphate of ammonia. The increase, however, 
both on Plot 4 and Plot 6 is considerable. 
4. That Peruvian guano, used on light land at the rate of 
4 cwts. per acre, in the dry season of 1867, did not produce 
as large an increase as in all probability it would have yielded 
in a more propitious season. Peruvian guano, it will be seen, 
gave an increase of only 1 ton 4 cwts. 1 qr. and 17 lbs., whilst 
the artificial manure, composed of superphosphate, potash-salts, 
and sulphate of ammonia, yielded an increase of 4 tons, 18 cwts., 
and 17 lbs., and produced 3 tons 14 cwts. and 3 qrs. more than 
Peruvian guano. 
5. That 4 cwts. of common salt added to 4 cwts. of superphos- 
phate per acre, was more than was good for the potato crop in a 
dry season. Practically speaking, the crop on Plot 8, manured 
with superphosphate and common salt, was the same as that of 
the unmanured land, for the apparent increase on Plot 8, amount- 
ing to only 9 cwts. 1 qr. and 17 lbs., falls within the range of 
the variations in the produce of the three unmanured Plots Nos. 
1, 5, and 10. 
Had 4 cwts. of superphosphate been applied alone, no doubt 
a better crop would have been produced than was obtained on 
Plot 8, where the addition of salt to superphosphate evidently 
did not exercise a beneficial effect upon the crop, but rather the 
reverse. 
6. That on all plots on which potash-salts were used the 
increase in the crops was considerable, and that, therefore, potash- 
salts are useful and very desirable constituents in a potato-manure, 
especially if it is intended to be applied to light land. 
Potato Experiments made in 1868 by Mr. Charles Hunter, at 
Blennerhasset near Carlisle. 
A series of potato experiments, similar to the preceding, was 
carried out in 1868 by Mr. Charles Hunter, who conducts the 
laboratory and field-experiments on Mr. W. Lawson's farm at 
Blennerhasset, near Carlisle. 
The potatoes, a variety of Regents known as Rough Whites, 
were planted rather late in the season, namely on the 4th of May, 
18G8, and the sets placed 8 inches apart in drills 30 inches wide. 
Each experimental plot comprised 4 stetches 36 yards long, 
equalling of an acre. 
The manures, mixed with screened earth, were sown broadcast 
before planting the potatoes. 
The soil of the experimental field was a friable deep sandy 
loam, and well suited for potatoes and root crops in general. 
