A52 MANURING OF POTATOES. 



Alike in the Yorkshire experiments of 1899 and in the Glas- 
gow experiments of 1898 the dressing of farmyard manure 
alone produced slightly Jarger crops, but in the Glasgow ex- 
periments of 1899 it was somewhat surpassed by the combined 
application of farmyard manure and artificials. In all the 
comparisons, however, the differences were slight. Prac- 
tically the crops were equal in the two methods of manur- 
ing, and the experiments have therefore shown that it is 
quite possible to grow as large crops of potatoes with a half 
dressing of farmyard manure as with a full dressing, provided 
the half dressing be supplemented with suitable artificials. 
What zs the most suttable Artificial Manure to apply along with 
farmyard Manure to the Potato Crop ? 
The majority of the plots in all the experiments were 
designed to supply an answer to this inquiry, and there is a 
general agreement in the main result. Tne evidence is 
ample, except in those experiments in which the artificials 
produced a very limited effect, that the artificial manure 
for this purpose must be a complete manure containing the 
three substances nitrogen, phosphoric acid, and potash, and 
that the omission of any one of these ingredients lessens 
the efficacy of the manure and reduces both crop and profits. 
The effects of using incomplete mixtures of artificial 
manures from which one of the three essential elements was 
omitted produced, however, somewhat variable results in 
the different series of experiments. This might depend 
partly on the total amount. of effect produced by the 
artificial manures, partly on the nature of the soil, and 
probably not a little on the quality and quantity of the 
farmyard manure employed, as well as on other conditions. 
The most successful combinations of artificials employed 
in the various series of experiments to supplement farm- 
yard manure have been already given, but special atten- 
may be again directed to those which produced the largest 
yields of crop in the Glasgow experiments of 1898 and 18g9. 
In 1898 the most effective combination was found to be :— 
1; _,, Nitrate of Soda. 
4 cwts. Superphosphate (30 per cent.) 
per acre. 
I cwt Sulphate of Potash (96 per cent.) 
