348  The  Woburn  Pot-Culture  Experiments,  1909. 
in  lime,  and  by  adding  to  it  lime  in  increasing  quantities  until 
the  amount  of  lime  equalled  that  of  magnesia.  For  this  pur- 
pose, a soil  from  Herefordshire  was  taken,  in  which  the  relative 
proportions  of  lime  and  magnesia  were  : — 
per  cent. 
Lime -83 
Magnesia 2-29 
Lime — as  burnt  (Buxton)  lime — was  added  to  the  soil  to 
make  up  its  lime  contents  respectively  to  : — 1'25  per  cent.,  1'50 
per  cent.,  l-75  per  cent.,  2 per  cent.,  and  2’25  per  cent.,  the  last 
addition  effecting  the  equalling  of  the  lime  and  magnesia  in 
the  soil.  At  first  the  untreated  lots  looked  much  the  best,  the 
additions  of  lime  showing  all  the  drawbacks  that  had  been 
similarly  noted  before  in  connection  with  the  addition  of 
magnesia.  In  all  cases,  however,  the  addition  of  lime  was 
marked  by  a great  increase  in  leaf  growth,  and  the  growing 
period  was  considerably  prolonged  also.  The  threshing  results' 
are  put  out  in  the  previous  table  (page  347). 
It  will  be  seen  from  these  results  that,  consequent  on  the 
addition  of  lime  up  to  l-50  per  cent.,  the  grain  was  much  the 
same  as  with  the  untreated  lots,  but  that  further  additions  of 
lime  decreased  the  yield.  In  all  cases  alike,  however,  of 
addition  of  lime,  the  amount  of  straw  was  increased.  These 
experiments  will  be  continued  for  a further  season. 
4.  The  influence  of  Magnesia  on  Clover  and  Beans. 
Magnesia  having  so  far  been  used  only  on  wheat  and  barley, 
it  was  decided  to  try  its  effect  on  clover  and  beans,  as  it  was 
thought  possible  that  the  question  of  nitrogen  assimilation 
might  be  affected  thereby.  Clover  was  sown  on  April  7 and 
beans  on  April  10,  1909,  magnesia  being  added  to  the  soil  (one 
containing  lime  -26  per  cent,  and  magnesia  09  per  cent.)  in 
quantity  to  make  the  soil  percentages  of  magnesia  respectively 
•05,  TO,  and  ‘20.  In  each  case  addition  of  magnesia  retarded 
the  germination  though  not  ultimately  affecting  the  final 
stage.  By  June,  however,  the  influence  of  magnesia  was 
clearly  shown  in  each  crop,  the  untreated  lots  being  much  the 
best,  while,  as  more  magnesia  was  added,  the  crop  became 
smaller  and  smaller.  Along  with  this  were  noticed  changes 
in  the  root  growth,  similar  to  those  observed  with  wheat,  the 
roots  becoming  more  fibrous  as  the  magnesia  was  increased.  It 
was  also  noted  that  nodule  formation  in  the  case  of  the  beans 
was  similarly  reduced. 
The  clover  crop  was  cut  the  first  time  on  August  12,  and  a 
second  time  on  December  11,  and  the  beans  were  reaped  in 
autumn.  The  following  table  gives  a summary  of  the 
results: — 
