306 The Woburn Field Experiments , 1905 and 1906. 
Table XV . — Potato Experiments ( Road Piece Field), 1905. 
Plot 
Manures per acre 
Produce of tubers per acre 
Ware 
Seed 
Total 
1 
. Superphosphate, 3 cwt. ; nitrate of 
socla, 1 cwt. ; sulphate of potash, 
T. c. q. lb. 
T. c. q. lb. 
T. c. q. lb. 
2 
1 cwt, ,*•••• 
Superphosphate, 3 cwt. ; nitrate of 
4 18 3 0 
12 2 0 
6 110 
3 
soda, 1 cwt. ; kainit, 4 cwt. 
Superphosphate, 3 cwt. ; sulphate 
of ammonia, 1 cwt. ; kainit, 
4 16 1 0 
0 18 3 25 
5 15 0 25 
4 
4 cwt. ...... 
Superphosphate, 3 cwt. ; sulphate 
of ammonia, 1 cwt. ; sulphate of 
4 14 2 21 
0 18 3 0 
5 13 1 21 
potash, 1 cwt. .... 
5 9 2 1 
0 17 2 0 
6 7 0 1 
These results supply a direct confirmation of those of 1904, 
the plots now occupying exactly the same relative positions 
in order of merit as they did then. Sulphate of potash has 
again proved better than kainit, whether used with sulphate 
of ammonia or with nitrate of soda ; and 1 cwt. of sulphate of 
ammonia per acre has, on the whole, done better than 1 cwt. 
of nitrate of soda. In each of the years, however, the com- 
bination of nitrate of soda and kainit has proved better than 
that of sulphate of ammonia and kainit, though it is hard to 
assign any reason for this being the case. It may now fairly be 
concluded that, for the potato crop on light land, 1 cwt. per 
acre of sulphate of potash is a better dressing than 4 cwt. of 
kainit, the two supplying practically equal quantities of potash. 
Nitrate of Soda and Salt for Mangels (Road Piece 
Field), 1905 and (Warren Field) 1906. 
The extent to which nitrate of soda can be profitably used 
as a top-dressing for mangels is often a matter of question ; so 
also is the use of common salt. On some heavy lands, where 
mangel is grown year after year, it may pay to use nitrate of soda, 
even up to 4 cwt. per acre, but this is not the practice of the 
ordinary farmer, who would confine himself, as a rule, to 1 cwt. 
or 1^ cwt. per acre. An experiment was devised on these 
lines and carried out in the two years, 1905 and 1906. Farm- 
yard manure, at the rate of 12 tons per acre, was ploughed in 
early in April, and mangel seed (7 lb. per acre) drilled sub- 
sequently. The top-dressings per acre were respectively : — 
plot 2, nitrate of soda 1 cwt. ; plot 3, nitrate of soda 1 cwt., 
salt 1 cwt. ; plot 4, nitrate of soda 2 cwt. ; while plot 1 had 
only the farmyard manure. The top-dressings were put on 
