The  Wohurn  Field  Experiments,  1909. 
385 
Table  XIII. — Experiments  with  Nitrogenous  Top-dressings, 
and  ivith  Magnesia,  on  Potatoes  (Warren  Field),  1909. 
Produce  of  Tubers  per  acre. 
Plot 
Manuring  per  acre 
Ware 
Seed  & pig 
Diseased 
Total 
produce 
1 
Standard  dressing' only 
T.  c.  q.lb. 
10  13  3 0 
T.  c.  q.  lb. 
3 3 0 14 
C.  q.lb. 
15  1 12 
T.  c.  q.  lb. 
14  12  0 26 
2 
Additionally — 
Sulphate  of  ammonia,  1 cwt. 
11  13  0 14 
3 8 3 0 
17  2 0 
15  19  1 14 
3 
Nitrate  of  soda^  .... 
11  5 0 0 
3 7 2 0 
16  2 12 
15  9 0 12 
4 
Calcium  cyanamide’ 
11  4 1 14 
3 6 2 12 
16  1 20 
15  7 1 18 
5 
Calcium  nitrate’  .... 
11  15  0 0 
2 17  2 0 
13  3 0 
15  6 1 0 
6 
Magnesia,  3 cwt 
10  8 0 14 
2 16  1 0 
13  2 18 
13  18  0 4 
7 
Magne.sia,  6 cwt 
9 8 1 21 
2 8 3 0 
12  3 12 
12  10  0 5 
8 
Carbonate  of  magnesia,  3 cwt. 
9 13  0 14 
2 15  1 7 
11  1 0 
12  19  2 21 
9 
Carbonate  of  magnesia,  6 cwt. 
9 17  3 7 
2 14  1 14 
13  1 16 
13  5 2 9 
10 
Magnesian  lime.  6 cwt.  . 
9 15  0 0 
2 17  0 21 
14  0 7 
13  6 1 0 
11 
„ limestone  (ground),  10  cwt. 
9 9 1 14 
2 14  0 12 
17  1 18 
13  0 3 16 
’ Dung  12  tons,  superphosphate  3 cwt.,  sulphate  of  potash  1 owt.  per  acre. 
2 In  quantity  to  supply  as  much  nitrogen  as  that  contained  in  1 cwt.  sulphate  of 
ammonia. 
The  results  in  these  series  of  experiments  will  now  be 
discussed. 
As  regards  the  wheat  crop  in  Lansome  Field,  it  must  be 
admitted  at  once  that  the  duplicate  plots  are  not  as  consistent 
as  one  would  wish.  It  is  clear,  however,  that  the  top-dressings 
have  in  all  cases  “ told.”  Averaging  the  duplicates  we  have 
the  following  : — 
No  top- 
dressing 
Sulphate  of 
ammonia 
Nitrate  of 
soda 
Calcium 
nitrate 
Calcium 
cyanamide 
Grain — bushels  per 
acre  . 
Straw  — cwt.  per 
12-4 
16-5 
19-6 
16-2 
171 
acre  . 
Gain  over  no  top- 
dressing— 
Corn  — bushels 
15  c.  3 qr. 
21c. 
23  c.  1 qr. 
21  c.  2 qr. 
17c. 
per  acre  . 
Straw — cwt.  per 
— 
4-1 
7-2 
3-8 
4-7 
acre 
— 
5 c.  1 qr. 
7 c.  2 qr . 
5 c.  3qr. 
1 c.  1 qr. 
The  best  result,  both  in  grain  and  straw,  was  thus  obtained 
from  nitrate  of  soda  ; sulphate  of  ammonia  and  calcium  nitrate 
being  practically  equal  in  both  corn  and  straw,  while  calcium 
cyanamide,  though  giving  slightly  more  corn  than  sulphate  of 
ammonia  and  calcium  nitrate,  yielded  considerably  less  straw 
than  either. 
Passing  next  to  the  barley  results  on  Great  Hill,  we  are  met 
at  once  with  the  diflSculty  that  the  produce  of  plots  5 and  8, 
on  which  no  top-dressing  was  given,  was  the  highest  of  the 
VOL.  70.  P p 
