100 INVESTIGATIONS ON EOTHAMSTED SOILS. 
Table 55. — Broadbalk wheat soils, samples collected in October, 1803. 
Plat. 
Annual manuring for 50 years (with only minor 
variations during earlier years). 
Phosphoric acid 
(P0O5) in fine dry 
soil (first 
inches). 
Average yield 
per acre (1889- 
1894). 
Total. 
Dissolved 
by 1 per 
cent citric- 
acid solu- 
tion. 
Wheat. 
Straw. 
3 
4 
10a 
10b 
7 
13 
14 
12 
11 
5 
2b 
2a 
Unmanured continuously 
Unmanured continuously since 1852 
Ammonium salts onlv, since 1844 
Ammonium salts only, since 1850 
Superphosphate and ammonium salts, with 
potassium, sodium, and magnesium sulphates.. 
Superphosphate and ammonium salts, with 
potassium sulphate . _ 
Superphosphate and ammonium salts, with 
Superphosphate and ammonium salts, with 
Superphosphate and ammonium salts only 
Superphosphate and potassium, sodium, and mag- 
nesium sulphates (no nitrogen). 
14 tons farmyard manure... 
14 tons farmyard manure (commencing in 
1884-85) 
Per cent. 
0. 114 
.120 
.123 
.126 
Per cent. 
0. 0OZ8 
.0100 
.0074 
. 0074 
Bushels. 
12* 
13£ 
16^ 
18 
Cwt. 
% 
m 
m 
195 
.205 
.204 
.201 
.197 
0547 
. 0434 
.0442 
.0413 
.0405 
OAs 
32| 
29^ 
29£ 
21f 
00% 
31} 
27b 
m 
.219 
.0642 
24f 
m 
.215 
. 165 
. 0560 
.0321 
40| 
30} 
38| 
28| 
These results may be condensed by averaging the four soils which 
have been wholly without phosphatic manure since 1850; and also the 
five soils continuously receiving superphosphate in conjunction with 
nitrogen. 
Table 56. — Broadbalk wheat soils, samples collected in October, 1S93. 
Plats. 
Annual manuring. 
Average percent- 
age of phosphoric 
acid in fine dry 
soil. 
Average yield per 
acre (1889-1894). 
Total. 
Dissolved 
by 1 per 
cent citric- 
acid solu- 
tion. 
Wheat. 
Straw. 
Per cent. 
Per rent. 
Bushels. 
Cwt. . 
I, (. Ida, and 10b ... 
0. L21 
0.0082 
m 
m 
7,13, 14,12,11 
Superphosphate and ammonium 
.200 
.0448 
m 
salts, with and without alkaline 
salts. 
r. 
Superphosphate and alkaline salts, 
. 219 
.0642 
14J 
10J 
without nitrogen. 
2b 
1 1 tons farmyard manure for 50 
.215 
.0580 
40? 
38| 
years. 
14 tons farmyard manure for 9 
. 165 
.0321 
30} 
28» 
years only. 
Of these lour groups of plats, the firsl is suffering from phosphatic 
starvation, aggravated, in two of the Tour plats comprising it, by a 
free supply of ammonium salts. The average yield has dropped to 
a Little over 15 bushels of grain per acre and less than L2 hundred- 
weight of straw. 
In the next group, of tive plats, superphosphate lias been freely and 
continuously supplied, as well as nitrogen in the form of ammonium 
salts, while on four out of the five plats of this group "alkaline" 
Salts (potassium, sodium, and magnesium salts, together or sepa- 
