384  The  Wohurn  Field  Experiments,  1909. 
dressings  were  applied  on  July  6.‘  The  only  special  occurrence 
noticed  in  connection  with  the  applications  was  that,  owing  to 
heavy  rain  just  after  the  top-dressings  had  been  given,  the 
mangold  leaves  were  beaten  down,  and  wherever  they  came 
in  direct  contact  with  the  calcium  cyanamide  they  were 
scorched  up  and  turned  quite  yellow,  and  this  although  the 
calcium  cyanamide  had  been  mixed  with  soil  before  spreading. 
From  this  injury,  however,  the  plants  quite  recovered  later 
on.  The  mangold  crop  was  a splendid  one  for  light  land  such 
as  that  of  Road  Piece,  and  there  was  not  the  equal  of  this  crop 
in  the  neighbourhood.  So  far  as  the  eye  could  judge,  the 
calcium  nitrate  plot  was  perhaps  the  best.  The  mangolds  were 
pulled  October  25-30  and  weighed.  The  results  are  given  in 
Table  XII. 
Table  XII. — Experiments  with  Nitrogenous  Top-dressings  on 
Mangolds,  1909. 
Koad  Piece  Field. 
Plot 
Manures  per  acre 
Produce  of  roots 
per  acre 
T. 
c. 
q. 
lb. 
1 
Standard  dressing^  with  sulphate  of  ammonia  1 cwt. 
32 
2 
2 
0 
2 
„ „ „ nitrate  of  soda^ 
36 
16 
3 
14 
3 
„ „ „ calcium  nitrate^ 
40 
16 
3 
14 
4 
„ „ ,.  calcium  cyanamide*  . 
37 
6 
2 
14 
5 
r ,1  only 
40 
15 
0 
0 
1 Dung  12  tons,  superphosphate  3 cwt.,  sulphate  of  potash  1 cwt.,  salt  2 cwt.  per  acre 
2 In  quantity  to  supply  as  much  nitrogen  as  that  contained  in  1 cwt.  sulphate  of 
ammonia. 
{d)  Experiments  with  Potatoes  {Warren  Field),  1909. 
Here  also  there  were  no  duplicate  plots,  but,  in  place  of 
them,  were  six  additional  plots  on  which  magnesia  in  different 
forms  was  applied,  and  which  will  be  dealt  with  under  the 
next  head.  Manure  to  each  of  the  plots  was  applied  May  1-21, 
1909,  as  follows  ; — 
London  dung  . . . . . . .12  tons  per  acre. 
Superphosphate  ......  3 cwt.  „ „ 
Sulphate  of  potash 1 „ „ „ 
“ Up-to-date  ” potatoes  were  then  set,  and  the  nitrogenous 
top-dressings  and  magnesia  applications  were  given.  The 
crop  was  a very  good  one,  but  “ potato  disease  ” appeared  early 
in  August.  The  nitrogenous  top-dressings,  one  and  all,  showed 
a very  vigorous  growth.  The  potatoes  were  dug  October  9-15 
and  the  crops  weighed.  The  results  are  given  in  Table 
XIII. 
