MANURING OF POTATOES. 453 


while in 1899 better results were got from 
I cwt. Sulphate of Ammonia. 
4 cwts. Superphosphate (30 per cent.} 
‘ per acre. 
17 cwts. Muriate of Potash (70 per cent.) 
Can Potatoes be successfully grown with Artificial Manures alone 
without Farmyard Manure ? 
This inquiry is of less practical value than those already. 
considered, for it is not recommended by anyone that a 
manure which has shown itself so suitable for the potato 
crop as farmyard manure should be entirely withheld from. 
it. Moreover, it is reccgnized that, however. efficacious 
artificial manures may be found under normal weather con- 
ditions, they are liable to prove much less effective than farm- 
yard manure in seasons ef drought. Hence those who recom- 
mend, as a result of their experiments, that farmyard manure 
should be applied to the potato crop in moderate rather than 
in large quantity, and that suitable artificials should be given 
with it, do not advise that reliance should be placed on 
artificials alone tu the entire exclusion of farmyard manure. 
Nevertheless there may occur circumstances in which farm- 
yard manure cannot be givenin any quantity,and when reliance 
has to be placed solely on artificial manures. If so, all the 
experiments in which suitable artificial manures have been | 
supplied in sufficient quantity show that in ordinary seasons 
they will be quite adequate to the production of good crops 
of potatoes. But it has also been demonstrated clearly 
enough in the various experiments, that, uuless the artificials 
be composed of a suitable combination of ingredients and be | 
given in sufficient quantity, they will not produce a yield 
of crop equal to that grown with full dressings of farmyard 
manure. In the Yorkshire experiments of 1898, for example, 
not one out of four combinations of artificials employed in 
the county series produced a crop equal to that grown on 
1o tons farmyard manure, and the experiments of 1899 gave 
similar results. In the Durham experiments of 1898, also, the 
best of four combinations of artificials fell far short of produc- 
ing a crop equal to that grown on 15 tons farmyard manure. 
On the other hand, inthe Durham experiments of 1899 four 
new combinations of artificials were employed, each of 
