Field Experiments on Potatoes. 
397 
amount of decomposed organic matter, wliich possesses in an 
eminent degree the power of absorbing and retaining moisture 
in the land. For this reason dung is particularly useful on land 
which, like many poor sands, suffers much in a dry season. 
It is worthy of special notice that common salt did no good 
whatever to the potato-crop. If anything, it had an injurious 
effect, which is the more remarkable as the soil upon which the 
salt was put was a light sand, or land which is generally sup- 
posed to be benefited by common salt. As far, however, as my 
experience goes, I am more and more constrained to look upon 
all very soluble saline manures as rather dangerous agents ; for I 
have noticed over and over again the injury which these kinds of 
fertilisers produce in dry seasons, especially if they are applied 
lather late in spring. Unless common salt or potash-salts can be 
applied to the land quite early in spring, or, at all events, not 
later than the beginning of March, I believe it would be better 
in nine seasons out of ten not to make any use of these very 
soluble matters, which require to be thoroughly washed into the 
soil, if they are to benefit the crops for which they are used. 
Potash-salts applied alone had a better effect than common salt 
in the preceding experiments, but the increase by the use of these 
salts was disappointing, as was also that obtained on plot 2, on 
which mineral superphosphate alone was employed. 
The mixture of superphosphate and crude potash-salts, it will 
be noticed, had a much greater effect than either substance 
applied alone. Thus whilst 4 cwts. of mineral superphosphate 
gave an increase of 8 cwts. and 1^- lbs. per acre, and 4 cwts. of 
crude potash-salts an increase of 4 cwts. 3 qrs. and 25 lbs., the 
mixture of the two produced an increase of 1 ton, 16 cwts. 1 qr. 
and 27 lbs., or whilst potash-salts increased the produce 12 per 
cent., and mineral superphosphate 20 per cent., the two mixed 
together gave an increase amounting to 91 per cent. 
Potato Experiments made in 1867 by Mr. George Maw, at] 
Benthall Hall, near Broseley. 
An elaborate series of experiments with crude potash-salts, 
mineral superphosphate, farmyard-manure, common salt, and 
mixtures of superphosphate and potash-salts, and superphosphate 
and common salt, was carried out in 1867, by my friend and 
former pupil, Mr. G. Maw, of Benthall. 
Potato sets of the Kin» of Fluke Potato, of similar weight 
(each set separately weighed), were used within each of the 
twelve series of seven experiments which were tried in different 
parts of the garden of Benthall Hall, and uniform conditions 
insured as far as possible. 
Mr. Maw carefully noted down the detailed results of his labo- 
rious experiments, which he incorporated in the following tables : — 
2 E 2 
