Rotation of Crops. 
633 
to the records relating to the potash in these crops, as given in 
the third division of Table IX. 
The figures show that, in the case of the beans, unlike that 
of the cereals, there is much more potash in the corn than in 
the straw ; indeed, more than twice as much of the potash of 
the crops was accumulated in the corn as in the straw ; 
indicating, therefore, a special requirement of it for the forma- 
tion of the final and most fixed product of the plant — the seed. 
Looking to the amounts of potash per acre in the total pro- 
duce, corn and straw together, of the rotation beans, it is seen 
that they take up very little more under the influence of the 
superphosphate than without manure ; the quantities averaging 
about 10 lb. per acre without manure, and scarcely 12 lb. with 
superphosphate. With the mixed manure, however, directly 
supplying potash for the previous root-crop, the amounts of it 
taken up were, in the one case 22 T 6, and in the other 
24 - 46 lb., or about twice as much as with the superphosphate 
alone. The influence of the previous supply of potash on the 
amounts of it taken up in the beans was, in fact, much greater 
than was that of the supply of phosphoric acid on the amounts 
of it taken up. 
But, as in the case of the phosphoric acid, so also in that of 
the potash, the continuously grown beans took up only about 
half as much as those grown in rotation ; proportionally more, 
however, where it had been supplied than where it had not. 
It will be remembered that, when discussing the amounts of 
produce of the bean crops, attention was called to the fact that 
throughout the experiments a really good agricultural crop was 
scarcely ever obtained ; and this of course must be taken into 
account when considering the amounts of the several constitu- 
ents of the crops. 
Comparing the amounts of potash stored up in the rotation 
clover with those in the rotation beans, it is seen that, even 
without manure and with very small produce, the clover, with 
its greater root-range and longer period of growth, gathered up 
about three times as much potash as the beans — about 30 lb. 
against only about 10 lb. in the beans. 
With superphosphate alone, whilst the bean crops contained 
only 10'82 and 12 - 80 lb. of potash, the clover contained 5763 
and 65’48 lb. That is, under the influence of the phosphatic 
manure, probably partly on the plant and partly on the soil, the 
clover had accumulated in the removed crop five or six times as 
much potash as the beans, from the soil itself; whilst, of the 
phosphoric acid itself, little more than twice as much was taken 
up in the clover as in the beans under the influence of the 
