346  The  Woburn  Pot-Culture  Experiments,  1909. 
the  other  had  any  influence  on  the  result.  Accordingly,  it 
was  decided  to  start,  with  barley,  two  sets,  in  the  former  of 
which  sulphate  of  iron  was  kept  at  one  figure,  viz.,  -02  per  cent, 
on  the  soil,  and  sulphate  of  manganese  gradually  increased 
from  ’005  per  cent,  to  "01,  ’02,  '03,  ‘045,  and  06  per  cent, 
respectively  ; and  in  the  latter,  sulphate  of  manganese  was 
kept  invariable  (02  per  cent.),  and  sulphate  of  iron  gradually 
increased  from  005  per  cent,  to  06  per  cent.  The  salts  were 
mixed  with  the  whole  of  the  soil  and  barley  was  sown  on 
April  7,  1909.  The  germination  period  showed  no  particular 
features  except  with  the  heaviest  application  (06  per  cent.)  of 
sulphate  of  manganese,  where  considerable  retardation  took 
place  ; nor  during  growth  were  there  any  marked  differences 
to  record.  The  crop  was  harvested  on  August  21,  and  the 
results  showed  all  round  a slight  stimulating  effect  from  the 
use  of  the  salts.  The  differences  in  weights  of  corn  and  straw, 
as  between  the  different  applications,  were  but  small  and  hardly 
call  for  mention  in  detail.  Taking  the  “ untreated  ” returns  as 
100,  the  “treated  ” results  ranged  from  101  to  114  in  the  corn 
and  from  107  to  125  in  the  straw.  No  clear  differences  could 
be  drawn  between  the  addition  in  increasing  amounts  of 
sulphate  of  iron  or  of  sulphate  of  manganese  respectively  ; all 
alike  gave  evidence  of  slight  stimulating  effect  produced.  The 
“ optimum  ” amount  that  can  be  added  has  not,  however,  been 
as  yet  decided. 
2.  The  influence  of  Lime  and  Magnesia  in  different  forms 
on  Wheat. 
Following  up  previous  work  with  lime  and  magnesia,  it 
was  decided  to  try  not  merely  lime  and  magnesia  as  such,  but 
to  employ  also  the  respective  limestones,  using  them  in  (a)  a 
coarsely-ground  and  (5)  in  a finely-ground  state.  Lime  and 
magnesia  were  employed  at  the  rate  of  1 ton,  and  the  limestones 
at  that  of  1’6  tons  per  acre,  as  calculated  to  supply  the  same 
amounts  of  lime  and  magnesia  respectively  as  the  burnt  stone. 
Buxton  limestone,  and  the  same  burnt  into  lime,  and  magnesian 
limestone  (obtained  from  Yorkshire),  and  the  same  burnt,  were 
employed.  The  soil  was  the  ordinary  Woburn  soil,  containing 
about  -26  per  cent,  of  lime  and  '09  per  cent,  of  magnesia,  and 
the  applications  were  given  by  mixing  with  the  top  3 in.  of 
the  soil  only,  so  as  to  imitate  what  would  be  done  in  practice. 
The  several  pots,  after  one  failure  through  frost  and  snow, 
were  sown  on  January  18,  1909.  The  germination  was  fairly 
regular,  and  by  May  the  finely-ground  limestone  lot  was 
superior  to  both  the  coarsely-ground  and  the  lime  lots,  the 
magnesia  lots — whether  as  burnt  or  ground  limestone — being 
inferior.  By  the  beginning  of  July  the  appearances  were 
