358  Nitrogen  as  Nitric  Acid,  in  the  Soils 
every  detail.  The  result  of  the  analysis  of  the  third  depth 
of  Plot  4o  (Table  VIII.)  has  been  rejected  as  plainly  excessive, 
and  the  figure  found  for  Plot  2o  substituted. 
In  calculating  the  results  of  the  analyses  into  pounds  per  acre, 
the  weight  of  fine  soil  in  the  first  9 inches  of  the  plots  of  the 
O A,  and  AA  series,  has  been  taken  as  2,527,879  lbs.,  this 
being  the  mean  weight  actually  found  in  the  0,  A,  AA,  and 
AAS  series.  The  first  9 inches  of  soil  of  the  plots  of  the  C 
series  (rape-cake)  have  been  taken  as  2,361,461  lbs.,  the  mean 
weight  in  this  series.  For  the  first  9 inches  of  Plots  71  and  72 
(receiving  farmyard-manure)  their  own  weights  have  been  taken. 
In  the  case  of  all  the  subsoils,  2,593,853  lbs.  have  been  taken 
as  the  weight  of  fine  soil  in  the  second  depth,  and  2,661,134  lbs. 
as  the  weight  in  the  third  depth,  these  being  the  mean  weights 
of  all  the  series  above  mentioned. 
In  considering  the  results  of  the  analysis  of  the  soils  in  Hoos 
Field,  we  must  bear  in  mind  the  time  of  year  at  which  the 
samples  were  taken.  We  have  not  to  do,  as  in  Broadbalk, 
chiefly  with  a recent  production  of  nitrates,  formed  in  the  soil  at 
the  end  of  summer  and  early  autumn,  but  with  the  nitrates  left 
in  the  soil  after  the  washing  of  the  autumn  and  winter  rains. 
The  total  amount  of  drainage  passing  through  the  60  inch  drain- 
gauge  during  the  seven  months  from  August  to  February  was, 
in  fact,  12‘5  inches.  Of  the  quantity  of  nitrates  which  has 
passed  into  the  subsoil  by  drainage  during  this  period,  we  get 
some  idea  from  the  results  already  given  relating  to  Broadbalk 
Field  (Tables  V.  and  VI.).  It  naturally  results  from  the 
washing  out  to  which  the  soils  have  been  subjected,  that  the 
nitrates  are  found  more  evenly  distributed  than  was  the  case 
in  the  Broadbalk  samples.  In  Broadbalk  Field,  omitting  Plot  9b, 
the  nitrates  were  distributed  throughout  the  first,  second,  and 
third  9 inches  of  soil  in  the  proportion  of  100,  59,  and  31.  In 
Hoos  Field  the  nitrates  are  distributed  through  the  same  three 
depths  in  the  proportion  of  100,  102,  and  88. 
There  are  only  four  plots  in  Hoos  Field  (Plots  lo,  4o,  4a, 
and  72)  where  the  manuring  has  been  identical  with  plots  in 
Broadbalk  (Plots  3&4,  5a,  6a,  2);  in  each  of  these  cases  the 
nitrates  found  in  Hoos  Field  are  distinctly  below  those  found 
in  Broadbalk  ; a result  partly  due  to  the  washing  of  the  Hoos 
soils  by  the  autumn  and  winter  rains,  but  also  partly  to  the 
smaller  residue  left  in  the  soil  by  a barley-crop. 
The  four  plots  in  the  O series,  which  have  received  no 
nitrogenous  manure  for  30  years,  give  a mean  of  19  0 lbs.  of 
nitrogen  as  nitrates  in  27  inches  of  soil.  The  entirely  un- 
manured plot  gives  15*7  lbs. 
The  four  plots  in  the  A series,  receiving  respectively  the 
