THE HROADJiALK WHEAT SOILS. 99 
The citric-acid results were obtained by treating a large quantity 
of soil, usually 200 grams, with 1 per cent citric-acid solution in the 
proportions of 1 liter of solvent to 100 grams of soil, the soil being 
kepi in dissolution for seven days with frequent shaking. A quan- 
tity of solution representing 50 grams of the soil was taken for the 
determination of phosphoric acid. 
The results for all the plats examined are given in fche following 
table: 
Table 54. — BnmcUnilk irhrat noils, snmjtlrs roUrrtrtf in October, 1SUJ — Phosphoric 
acid determinations. 
Plat. 
Annual mairateg 
Total phosphoric acid. 
Phosphoric acid dissolved hy a 1 
per cent solution of citric acid. 
First 
depth. 
Sect >nd 
depth 
Third 
depth. 
First 
depth. 
Second 
depth. 
Third 
depth. 
1 
U 
Oh 
i 
it 
V 
cu 
i 
■ 
o 
h 
m 
i . 
/ • 
IS 
l 
d 
■ 
u 
Pounds per 
acre 
a 
■ 
B 
u 
C 
t 
§5 
a 
Q 
u 
Cm 
a 
8 

CU 
Pounds per 
acre. 
2a 
lb 
1 
4 
lite 
tin. 
u 
12 
U 
14 
Fa rin y :i r d ma 
atura since ISM 
Fa r in y a rd inn 
mire .Vi years 
l nmanured .... 
Untnanurod since 
1K52 .. 
Full minerals 
Full minerals and 
anmioniumsalts 
Aminoniuin salts 
i DO m i n e ra Is 
since 1844) 
Ammonium salts 
i no in i imrals 
sin<-«> ls.V) i 
Phosphates a n <1 
ammonium salts 
Phosphates, sodi- 
um and ammo- 
nium salts 
Phosphates po- 
tassium, a D d 
ammonium salts 
Phosphates, matf 
nesium.andain- 
monium salts . . . 
0. 105 
.114 
.153 
.219 
. us 
m 
. IS? 
.m 
M 
.264 
A, Ml 
."..Ills 
2.950 
8, 1 1 1 
5,878 
5,068 
:i. 188 
5, 107 
5,211 
5,816 
5,288 
0. otc. 
m 
.118 
. KM 
. 1M7 
.080 
111 
. ISO 
. ins 
.898 
. 105 
.ill 
8,681 
8,980 
8,019 
8,881 
8, 858 
8,291 
2.905 
2,885 
2,818 
2,805 
2.905 
0.084 
ii-:; 
. 007 
. <R»7 
.112 
. 07# 
. 105 
111 
.081 
.881 
.0*1 
.118 
8,845 
2. .!17 
8, 708 
8. me 
8, 126 
2,886 
8,883 
5,008 
8,540 
2,289 
8,281 
8, 154 
8.8881 
.0588 
.0(>78 
.(110(1 
.8842 
ji->\: 
.0074 
.0074 
. 0405 
.0418 
.0134 
.0042 
nr. 
1,867 
:.'<e 
1 . 686 
1. lis 
182 
198 
1,050 
1,071 
1,126 
1 . 1 16 
a 0052 
0094 
.0041 
.0024 
.0052 
.0088 
.(KKJl 
.0048 
.0028 
. 0085 
.0027 
.0023 
189 
251 
110 
84 
188 
102 
88 
US 
75 
!»4 
61 
0. 0028 
.0021 
.0017 
.0086 
.0080 
.8018 
.INC.M 
.0017 
.0020 
.0010 
.0023 
78 
85 
59 
48 
Mil 
84 
. 
59 
u 
5(5 
45 
(54 
I would first direct attention to the figures representing the con- • 
tents of the Surf ace soil or lirsl 9 inches, for it is in this depth that 
■he variations in phosphoric acid are mainly found, the greater part 
of the unused phosphates applied to a soil containing so much clay as 
the Rothanisted loam being evidently mainly retained in the surface 
soil, though, as we shall see, some port ion does, under some condi- 
t inns, find its way into i he subsoil. 
The following table shows the percentages of total and citric-acid- 
soluble phosphoric acid in each separate plat, and the average yield 
of grain and straw for six recent years, viz, L889-1894, the last named 
being the season following the soil sampling: 
