Clover as a Preparatory/ Crop for Wheat. 419 
is grown for seeds ; thus cxplainin<^ intelligibly, as it appears to 
me, why wheat, as stated by many practical men, succeeds better 
on land where clover is grown lor seed than where it is mown 
for hay. 
All the three layers of the soil after clover-seed are richer in 
nitrogen than the same sections of the soil where the clover was 
twice mown, as will be seen by the following comparative state- 
ment of results. 
I. 
II. 
Clover-soil twice Mown, 
Clover-soil once Mown, and then 
left for Seed. 
Upper 
6 inches. 
2nd 
6 inches. 
3rd 
6 inches. 
Upper 
6 inches. 
Next 
6 inches. 
Lowest 
6 inches. 
Percentage of nitro-"! 
gen in dried soil . . / 
•168 
•092 
•064 
•189 
•134 
•089 
Equal to ammonia . . 
•198 
•112 
•078 
•229 
•162 
•108 
This difference in the amount of accumulated nitrogen in 
clover-land appears still more strikingly on comparing the total 
amounts of nitrogen per acre in the different sections of the two 
portions of the 11-acre fields : — 
Percentage of nitrogen per acre :— « '^^<'^- ^nd s^^ches. 3rd « i^^iies. 
*I. In soil, clover twice over ] 3350 .... 1875 .... 1325 
fl. In soil, clover once mown and seeded > ^^25 3350 22^5 
afterwards j 
Equal to ammonia : — 
*I. Clover twice mown " ..1 4050 .... 2275 .... 1600 
t II. Clover seeded J 5725 .... 4050 .... 2700 
I. Nitrogen in roots of clover twice mown \ 24^ 
II. Nitrogen in clover, once mown and> g-j^^ 
grown for seed afterwards . . . . J ^ 
I. Weight of dry roots per acre from Soil I.) 1493-2- 
II. Weight of dry roots per acre from Soil II. j 3622 
*Total amount of nitrogen in 1 acre 121 5249* 
inches deep of Soil I I * 
tTotal amount of nitrogen in 1 acre 121 019^1 
inches deep of Soil II j "^^"^ 
* Equal to ammonia 1 6374| 
t Equal to ammonia J 9867 
Excess of nitrogen in an acre of soil 12 1 
inches deep calculated as ammonia in I 3502 '- 
part of field mown once and then [ ^ 
seeded I 
It will be seen that not only was the amount of large cloVer- 
roots greater in the part where clover was grown for seed, but 
that likewise the different layers of soil were in every instance 
