216  Report  on  the  Field  and  Feeding  Experiments  at  Woburn. 
land.  They  were  undertaken  with  the  object  of  throwing  light 
on  the  intricate  and  difficult  question  of  the  gradual  exhaustion 
of  soils  by  corn-crops.  It  is  hoped  that,  by  studying  the  special 
lunctions  of  various  nitrogenous  and  mineral  manures,  in  the 
course  of  time  data  will  be  furnished  which  will  materially  help 
agricultural  economists  to  entertain  more  correct  views  on  the 
subject  of  the  unexhausted  value  of  dung  and  of  artificial 
manures  than  is  the  case  at  present  with  the  majority  of  agri- 
cultural writers,  land  valuers,  land  owners,  land  agents,  tenant- 
farmers,  and  others  interested  in  this  important  question. 
For.  the  past  five  years  two  of  the  experimental  plots,  I may 
remind  the  reader,  were  manured  with  excessively  large  quan- 
tities of  mineral  and  nitrogenous  manures.  One  of  these  plots, 
in  addition  to  3J  cwts.  of  good  mineral  superphosphates, 
200  lbs.  of  sulphate  of  potash,  100  lbs.  of  sulphate  of  soda,  and 
100  lbs.  of  sulphate  of  magnesia  per  acre,  applied  every  year  in 
autumn  or  early  in  spring,  was  top-dressed  in  spring  with 
400  lbs.  of  salts  of  ammonia  per  acre;  and  another  plot  was 
similarly  dressed  with  the  same  minerals  and  550  lbs.  of  nitrate 
of  soda  per  acre,  containing  as  much  nitrogen  as  the  400  lbs.  of 
ammonia  salts  on  plot  8. 
Two  other  plots  were  manured  every  year  with  good  rotten 
dung.  On  one  of  these  plots  about  4 tons  of  dung  per  acre, 
specially  prepared,  and  estimated  to  contain  100  lbs.  of  ammonia 
per  acre,  had  been  applied  for  the  last  five  years ; and  on  the 
second  (plot  11),  double  the  quantity  of  dung  per  acre,  cal- 
culated to  contain  200  lbs.  of  ammonia,  had  been  used  every  year. 
With  a view  of  determining  experimentally  to  what  extent 
nitrogenous,  or  readily  soluble,  manures  like  nitrate  of  soda  and 
sulphate  of  ammonia,  applied  to  corn-crops  in  the  preceding 
year,  were  taken  up  by  the  plants,  and  carried  off  in  the  crop,  or 
wasted  in  land  drainage,  the  quarter-acre  plots  8 and  9,  heavily 
manured  every  year  with  expensive  mineral  and  readily  soluble 
nitrogenous  fertilisers,  were  divided  in  two  equal  parts  of 
one-eighth  of  an  acre  each.  Both  halves  were  dressed  with  the 
usual  quantity  of  mineral  manures,  but  only  one-half,  or  one- 
eighth  of  an  acre,  was  top-dressed  in  spring  with  nitrogenous 
manures.  Plot  8b  (one-eighth  of  an  acre)  was  top-dressed  on 
the  7th  of  April,  1882,  with  ammonia-salts,  at  the  rate  of 
400  lbs.  per  acre  ; and  plot  9b  on  the  same  day  was  top-dressed 
with  nitrate  of  soda,  at  the  rate  of  550  lbs.  per  acre. 
The  two  plots  Nos.  10  and  11,  dunged  every  year  in  the 
previous  five  seasons,  were  divided  into  two  equal  halves  of 
one-eighth  of  an  acre  each.  No  dung  was  put  upon  one-half, 
and  the  usual  quantity  on  the  second  half. 
By  this  arrangement  it  appears  to  me  possible  to  ascertain  in 
