This  must  emphasize  a  fact  which  it  is  exceedingly  important  to
keep  in  mind  while  studying  the  results  from  Broadbalk  field;
and  indeed,  when  studying  the  data  from  not  only  the  Rothamsted
fields  but  from  nearly  all  of  the  oldest  soil  experiment  fields  in


364    INVESTIGATION    BY   CULTURE   EXPERIMENTS


fc       3

o   pq


00

0    •*

01   o   PO  to

i»

00    O    ON  O    "

PO  "

00    PI    Pi

bo^o      "^  -2  <n       fe

K

Oi

ro  "

"     01     PO  *

S>

PI    PI    PO  ro  Ol

ro  ro

>->    ro  PI

a  _o       S  S  S       o

r~

1^  n

IO  ONO    t^

n

O    «  O   t^O

M     t-

ON  O    O

n-sS      3  a_o     -g

H

»

PO  Os
PO

M    PO  PO  •<!•

M    01    ro  ro

0^

5-  S,  q.  $%

PO  •*

rO  rO

O    M    ON

M      PO  01

5

NO

NO      •*

H     »^t-.lO

ON

00  00  00     ONO

PI    M

to  tooo

4=  c"     ^  ^Ja     -S

2"

PO  •*

^TcTpo?

1,

PI    PI    ON  O    O

01    ro

ON  POO

^~*  y      -4-»  ^  Q^     rt

o

^

to"to

O    fO  *"*»  *O

^.
t^ONto^  0

to  PI

o  to  t^

Jg      ^-u'o      -2

s

§

OO    PO
ro  M

•*t  w    O    O

NO

W5

O  00    O    ONO
«    «    PO  ro  PI

PO  PO

IO   M     PI

PI    PO  PI

H

Tf

PO  PI

NO

Tf    Tj-    ON  O     PI

•H      H

o  v:  CN

>

a

PI  TJ-
PI

'„-

O   P*  to  M  t-«-

PO  *

PO  O  00

ii3  ^H         tn  £
3               S   ">   C         0

H  o

§

t^o

=6  J|  -.
