Report  on  Wheat-Mildew. 
655 
mildew  if  that  is  the  prevailing  disease,  but  the  power  of  resistance  to  disease 
is  greatly  affected  by  the  condition  of  the  soiL  In  both  the  years  referred  to 
the  proportion  of  offal  com  to  100  dressed  in  the  same  field,  did  not  exceed 
four  and  seven,  but  in  these  cases  the  land  was  well  and  judiciously  manured. 
Plants  are  very  much  like  ourselves,  their  power  to  escape  disease,  and  to 
struggle  against  it  when  attacked,  depend  very  much  upon  their  state  of  health. 
“ Yours  truly, 
“ J.  B.  Lawes.” 
I have  now  to  present  some  very  important  communications 
which  I have  received  from  Dr.  Voelcker.  The  first  is  as 
follows  : — 
“Royal  Agricultural  Society  of  England, 
“ Laboratory,  1 2,  Hanover  Square,  London,  W. 
“ Nov.  22,  1882. 
“ Dear  Mr.  Litti.e, 
“ I believe  the  soil  has  a great  deal  to  do  with  mildew.  Only  about  a 
fortnight  ago  I sent  a report  to  Mr.  John  Oxley,  Stowe,  Buckingham,  who 
sent  me  a soil  upon  which  his  wheat  (and  also  beans)  became  more  or  less 
blighted  during  the  last  six  or  seven  years. 
“ He  grew  plenty,  but  not  good  healthy  straw,  but  at  a certain  stage  it  got 
blighted,  and  the  com  was  miserable. 
“ The  composition  of  the  soil  is  so  instructive  that  I give  it  to  you.  If  you 
should  make  public  use  of  it  I should  require  to  ask  Mr.  Oxley’s  permission. 
“ The  soil  in  a perfectly  dry  state  contains  in  100  parts : — 
^Organic  matter  and  combined  water  12 '97 
Oxide  of  iron 6*50 
Alumina 9 • 03 
Carbonate  of  lime 1'07 
Sulphate  of  lime  '51 
Magnesia ’56 
Potash  1 • 07 
Soda -18 
Phosphoric  acid  '10 
Insoluble  silicates 68 ' 01 
100-00 
* Containing  nitrogen  '45 
Equal  to  ammonia '55 
“ The  soil  was  a very  stiff  clay  soil,  resting  on  a nasty  yellow-coloured  still 
stiffer  clay  subsoil,  which  unfortunately  came  to  within  four  inches  to  the 
surface. 
“ I give  you  an  abstract  of  my  Report : — 
Your  soil  is  unusually  rich  in  nitrogenous  organic  matters,  and  it  also 
contains  more  potash  than  most  clay  soils,  which  accounts  hilly  for  the  fact 
that  your  wheat  and  beans  got  blighted,  and  made  lots  of  straw  and  haulm  in 
wet  and  cold  seasons  like  those  we  have  had  for  the  last  six  or  seven  years. 
On  the  other  hand,  your  soil  is  very  deficient  in  phosphoric  acid,  and  not  over 
rich  in  lime.’ 
“ This  is  a very  instructive  case,  for  it  confirms  the  frequent  observations 
which  l have  made  in  various  parts  of  England,  namely,  that  an  excess  ot 
available  nitrogenous  food  (be  it  nitrate  of  soda,  ammonia  salts,  or  organic 
matters  which  are  readily  decomposed  in  the  soil)  appears  to  me  to  have  a 
decided  tendency  to  cause  mildew  in  wheat.  On  the  other  hand,  phosphate  of 
