656 
Report  on  Wheat-Mildew. 
lime,  of  which  there  always  is  a considerable  residue  in  the  land  when  a crop 
of  mangolds  is  heavily  manured  with  bone-manures  or  guano,  as  is  now 
almost  invariably  the  case,  has  a tendency  to  produce  early  maturity. 
“ I do  not  know  any  crop  which  exhausts  the  land  as  much  of  available 
nitrogen  as  a crop  of  mangolds,  or,  speaking  generally,  a root-crop.  On 
the  other  hand,  a good  crop  of  clover  leaves  on  the  land  an  enormous 
quantity  of  nitrogenous  food,  as  3’ oil  will  see  if  you  turn  to  my  paper  in 
the  ‘ Journal  ’ on  “ Clover  as  a preparatory  crop  for  Wheat.”  I have  a very  strong 
conviction  that  an  excess  of  nitrogenous  food  in  the  soil  as  manure  renders 
wheat  liable  to  the  attack  of  mildew ; for  I know  as  a fact  that  an  excess  of 
nitrogenous  food  retards  in  a marvellous  manner  the  ripening  of  corn  crops, 
and  is  in  all  very  warm  seasons,  or  in  hot  climates,  but  most  objectionable  in 
cold  soils,  and  cold  and  wet  seasons,  and  because  the  nitrogenous  food,  as  we 
all  know,  at  first  causes  great  luxuriance  of  growth,  especially  if  the  early 
part  of  summer  is  warm  and  promising,  and  the  weather  then  suddenly 
changes  and  turns  cold  and  wet. 
“ Of  course  the  mischief  done  by  an  excess  of  nitrogenous  food  in  the  soil  is 
greater  on  a cold  clay  soil  than  on  a lighter  and  naturally  warmer  and  natu- 
rally well-drained  soil.  However,  even  on  our  light  Woburn  land  I have 
noticed  for  several  years  that  the  plots  which  were  manured  with  a heavy  dose 
of  nitrate  of  soda,  or  with  ammonia  salts,  were  more  blighted  than  others 
manured  with  less  nitrate  or  ammonia  salts. 
“ My  impression  is  that  a sudden  check,  by  cold  or  continued  wet  weather, 
has  a decided  tendency  to  favour  the  attack  of  mildew  in  wheat,  and  that  this 
tendency  is  greater  in  highly  manured  land  than  in  poorer  soils,  or  at  all 
events  on  land  which  is  manured  with  too  much  nitrogenous  food,  or  on  land 
naturally  rich  in  such  food. 
“ Believe  me,  dear  Mr.  Little, 
“ Yours  faithfully, 
“Augustus  Voelcker.” 
This  direct  confirmation  of  the  suspicion  that  certain  soils 
were  peculiarly  liable  to  mildew,  and  that  under  a particular 
treatment  that  liability  was  greatly  increased,  seems  to  me  to  be 
very  notable.  In  order  to  ascertain  whether  the  soils  with 
which  I have  to  do  were  similar  to  the  Bucks  soil,  of  which  Dr. 
Voelcker  has  written  in  the  preceding  letter,  1 sent  him  four 
samples  of  soil  from  my  own  farm,  representing  four  different 
classes  of  soil  which  are  found  in  this  neighbourhood.  With 
the  permission  of  the  Chemical  Committee  of  the  Society,  these 
were  analysed,  and  the  result  communicated  to  me  for  the 
purpose  of  this  paper.  A few  words  as  to  the  agricultural 
characteristics  of  these  soils  may  be  necessary  before  Dr. 
Voelcker’s  analysis  is  examined. 
No.  1 represents  the  medium  strong  soil  of  this  district.  Like 
nearly  all  the  soil  on  my  farm,  it  has  been  deposited  by  the 
tide.  It  is  not  nearly  so  tough  and  heavy  as  much  of  the  Marsh- 
land district,  and  it  can  generally  be  ploughed  with  two  horses. 
No.  2 represents  another  and  lighter  alluvial  deposit,  in  which 
a soft  sand  is  present  in  sufficient  quantity  to  make  the  land 
work  freely  in  almost  all  seasons.  This  description  of  land  is 
known  locally  as  “ silt.” 
