98 
INVESTIGATIONS ON ROTHAMSTED SOILS. 
Table 53. — Broadbalk wheat plats. 
Manure per acre per annum. 
Unmanured continuously 
Unmanured continuously 
since 1852 (previously super- 
phosphate and ammonium 
salts) 
Ammonium salts alone since 
1844 (mineral manure in 1844) 
Ammonium salts alone since 
1844, except in 1846, 1848, and 
1850 (mineral manure in 1844, 
1848, and 1850) 
Ammonium salts and super- 
phosphate, with 200 pounds 
potassium sulphate (300 
pounds up to 1858), 100 
pounds sodium sulphate (200 
pounds up to 1858), and 100 
pounds magnesium sulphate . 
Ammonium salts and super- 
phosphate, with 200 pounds 
potassium sulphate (300 
pounds up to 1858). No so- 
dium or magnesium salts 
Ammonium salts and super- 
phosphate, with 280 pounds 
magnesium sulphate ( 420 
pounds up to 1858). No so- 
dium or potassium salts 
since 1850 
Ammonium salts and super- 
phosphate, with 360.V pounds 
sodium sulphate ( 550 pounds 
up to 1858). No potassium or 
magnesium salts since 1851.. 
Ammonium salts and super- 
phosphate only. No potas- 
sium, sodium, or magnesium 
salts. 
Superphosphate, with potas- 
sium, sodium, and magne- 
sium sulphates, as on plat 
7, but no nitrogen 
14 tons farmyard manure(1843- 
44, and every year since) 
14 tons farmyard manure, com- 
mencing in 1881-85 
Average 
yield per 
acre for 42 
years, 
1852-1893. 
33| 
3H 
30f 
30i 
m 
14f 
34£ 
Cwt. 
m 
20 
32f 
31£ 
284 
23 
Average 
yield per 
acre for 6 
years, 
1889-1894. 
Bu. Cwt. 
12f 9 
13| 
16* 
18 
32f 
294 
291 
21f 
14; 
40i 
301 
Phosphoric 
acid. 
Potash. 
Esti- 
mated 
addi- 
tion in 
ma- 
nures 
during 
50 
years. 
Esti- 
mated 
remov- 
al in 
crops 
during 
50 
years, a 
Lbs. 
506 
82 
210 
3, 107 
3, 181 
3,216 
3, 189 
3, 153 
3,256 
3,920 
Esti- 
! mated 
! addi- 
tion in 
ma- 
nures 
during 
50 
years. 
Lbs. 
467 
528 
582 
650 
1,122 
1,061 
1,016 
1,C05 
861 
674 
1,301 
Lbs. 
235 
74 
374 
5,037 
5,287 
6566 
/>588 
b 15 
5,203 
11,760 
Esti- 
mated 
remov- 
al in 
crops 
during 
50 
years.d 
a Estimated from analysis of separate samples of grain and straw from each plat. 
6 Applied prior to 1852. 
Phosphoric acid. 
General Discussion and Statement of Analytical Results on Broadbalk 
Soils and Subsoils of 189:5. 
The total phosphoric acid was in each case determined in 10 grains 
of the dry soil by Ignition and extraction with acid, duplicate deter- 
minations having in all cases been made, one with nitric acid as a 
solvent and the other with hydrochloric acid, the chlorin in the: 
latter case being Dearly eliminated from the solution after removal of 
the silica by repeated evaporation with nitric acid before adding the 
molybdic solul ion. 
