377 
On  the  Power  of  Soils  to  absorb  Manure. 
practice  of  burning,  or  of  using  burnt  clay  as  manure* — a practice 
which  must  stand  or  fall  upon  its  own  merits. 
The  perfect  comminution  and  disintegration  of  the  soil,  how- 
ever effected,  must  render  it  more  fertile,  and  place  it  in  a position 
to  benefit  by  the  manuring  influences  of  the  atmosphere  and  rain, 
which  are  probably  much  greater  than  we  at  all  conceive.  Had 
Jethro  Tull  been  aware  of  the  property  which  we  have  been 
engaged  in  considering,  he  would  in  his  intelligence  have  placed 
it  foremost  in  the  rank  of  those  arguments  by  which  his  system  of 
cultivation  was  maintained.  That  he  had  a conviction  of  the  ex- 
istence of  some  such  power  in  the  soil,  and  of  a manuring  power 
in  the  air,  there  can  be  no  doubt ; and  since  we  have  seen  that  a 
worked  soil,  although  it  contains  perhaps  only  half  its  weight  of 
clay,  is  yet  more  active  as  an  absorbent  than  pure  clay  itself,  we 
have  further  reason  to  believe  in  the  wonderfully  beneficial  effect 
which  Tull  attributed  to  abundant  stirring  and  trituration  of  the 
* The  action  of  burnt  soil  rests,  I believe,  on  some  distinct 
principle  not  hitherto  understood.  Its  effect  upon  the  Oxford 
clay  has  been  twice  brought  by  me  before  the  Society  in  this 
Journal,  vol.  vi.,  p.  478,  and  more  recently,  vol.  ix.  p.  422.  It  is 
quite  evident  that  the  action  is  not  a merely  mechanical  one  of 
opening  the  soil,  but  decidedly  chemical.  The  last  instance  is 
conclusive  on  that  point : for  while  four  good  crops  of  corn  were 
thereby  grown  in  succession  on  a cold  clay,  the  ashes  were  not 
even  mixed  with  the  soil,  being  merely  turned  over  with  the 
breast-plough.  The  burning  of  clay  does  not  answer  on  all  clay 
soils,  but  it  does  answer  on  most  of  them,  especially  on  the  Oxford 
clay,  which  crosses  England  in  a wide  band  ; it  answers  also  in 
Essex,  Cambridgeshire,  Bedfordshire  (vol.  iii.  p.  323),  and  in 
Worcestershire.  Mr.  Randall’s  account  of  the  process  in  vol.  v„ 
p.  1 13,  should  especially  be  consulted  by  the  owners  and  occupiers 
of  heavy  land  at  the  present  time.  But  to  return  to  the  theory  of 
burning  soil.  Mr.  Bravender,  in  the  present  number,  p.  160, 
states  the  good  effect  of  the  practice  of  stifle-burning.  The  most 
remarkable  proof,  however,  is  the  circumstance  that  on  peaty 
soils,  and  on  stonebrash  soil  also,  where  each  heap  has  been 
burned,  though  the  ashes  have  been  carefully  removed,  the  utmost 
luxuriance  of  vegetation  follows  on  the  particular  spot,  and  in 
contrast  sometimes  with  utter  sterility.  I cannot  but  think  that 
the  effect  may  be  due  to  the  disintegration  and  decomposition  of 
the  soil  bringing  some  of  its  chemical  constituents  from  a dormant 
into  an  active  state,  and  I should  think  it  would  well  reward  a 
chemist  to  examine  into  the  whole  question  of  the  Torrefaction  of 
Soils. — Pu.  Pusey. 
