638 
Rotation of Crops. 
Thus, then, the actual and relative importance of potash and 
lime in the growth of the highly nitrogenous leguminous crops is 
clearly illustrated in the acreage amounts given, of potash in 
the third division of Table IX., and of lime in Table X. But 
the study of the percentage composition of the ashes of the 
crops, and especially of both the percentage composition of the 
ashes, and the amount of the constituents per acre, in the bean 
plant taken at different stages of its growth, and of somewhat 
similar results relating to the first, second, and third crops of 
clover, affords further confirmation of the conclusions which 
have been drawn from the results already considered. It will 
be impossible to go into any detail here in regard to these 
further results, and it must suffice to state very briefly their 
general indications. 
The bean-plant ash analyses showed that, on the average, 
about 75 per cent., and at the time of pod formation nearly 80 
per cent., of the total ash consisted of lime, potash, and carbonic 
acid. Compared with these results, those relating to the more 
highly nitrogenous clover, which is not allowed to ripen, but is 
cut when it reaches the blooming stage, so inducing re-growth 
and extension of the more specially vegetative stages, show that 
from about 80 to about 84 per cent, of the total ash consisted of 
lime, potash, and carbonic acid. But whilst in the ash of the 
ripened corn-yielding bean-crop there was about one-and-a-half 
time as much potash as lime, in that of the merely vegetating 
unripened clover there was twice or even three times as much 
lime as potash. Further, in the ash of the first and third crops 
of clover, which would be the most succulent and unripe, the 
relative excess of lime over potash is much greater than in that 
of the second crop, which develops at the period of the season 
when the seed-forming tendency is much the greater. Again, 
in the clover ashes there was about one-and-a-half time as much 
carbonic acid as in the ash of the ripened bean plant. It is 
thus further illustrated that a peculiarity of the composition of 
these pre-eminently nitrogen-assimilating elements of rotation 
is, that their ashes consist chiefly of lime, potash, and carbonic 
acid ; that the potash predominates in the ripened and less 
nitrogen-yielding bean-crop ; and that the lime and carbonic 
acid predominate in the continuously vegetating and much 
more largely nitrogen-accumulating clover. 
Referring to the probable or possible significance of these 
facts, it is obvious that, so far as the nitrogen of the plant is 
taken up as nitrate of a fixed base, that base, so far as it does 
not pass back into the roots, will remain in the above-ground 
parts of the plant, most probably in combination with an organic 
