Field Experiments on Potatoes. 
409 
sulphate of ammonia in tlie mixture used upon Plot 2 by nitrate 
of soda, jis before, had a much less favourable effect upon the 
potato crop than the artificial manure employed on Plot 2. 
Again, it is shown in these experiments, that in a dry season 
Peruvian guano in a great measure remains inactive in the soil, 
and does not produce so large an increase in the potato crop as 
it is known to yield in a season in which copious and repeated 
rains dissolve and distribute the guano more perfectly in the soil 
to which it is applied. 
Relying on the experience gained at Escrick and Blenner- 
hasset, it appears to be hazardous to apply in a dry season as 
much as 4 cwts. of common salt to the potato crop. 
Plot 8, upon which superphosphate and salt were employed, 
actually gave a slight decrease in comparison with the average 
produce of the unmanured plots, and thus the salt appears to have 
affected the potato plants injuriously. Speaking in general terms, 
the Blennerhasset experiments furnish corroborating evidence 
that a good potato manure for light land ought to be composed 
mainly of a mixture of available phosphates with a fair proportion 
of sulphate of ammonia and salts of potash. 
Potato Expeeiments ix 1869. 
The same manures which were employed in the preceding 
experiments were again tried in 1869, in two series of experi- 
ments. One series was carried out on a stiffish clay loam in the 
County of Durham, by my former pupil, Mr. G. Y. Wall, jun., 
and the other on light land, by Messrs. Coleman & Hull, of 
Escrick Park. The best thanks of the agricultural public are 
due to these gentlemen for the interest they showed at all times 
in my experimental enquiries, and the care and trouble which 
they took with these field trials. 
Potato Experiments made in 18G9 hy Mr. G. Y. Wall, jun.y 
Exchequer Offices, Durham, at The Lizards, near Sedgjield, 
Ferry tiill, in the County of Durham. 
The land on which the experiments were made is situated on 
the Carboniferous formation, and the soil of the experimental field 
was a rather stiffish clay loam. 
Before planting out the potatoes, the manures, mixed with 
screened earth, were sown broadcast, and the ground planted, on 
the 13th of April, 1869, with Regents in whole sets, 78 lbs. of 
potato sets being appropriated to each experimental plot of 
of an acre. 
The crop was harvested on the 8th of November, 1869, wet 
weather having prevented its being done earlier. The potatoes 
were sorted and weighed in three lots, and each lot carefully 
