246 



THE ROTHAMSTED EXPERIMENTS. 



Propor- 

 tions of 

 lime, 

 potash, 

 and car- 

 bonic acid 

 in the ash 

 of plants, 

 and their 

 relation to 

 the assimil- 

 ation of 

 nitrogen. 



more directly connected with the accumulative or vegetative, 

 as distinguished from the maturing processes of the plant. 

 Certain it is, at any rate, that a largely increased accumula- 

 tion of lime is a coincident of increased luxuriance in both 

 crops ; and it is especially so in the case of the crop the 

 amount of which depends on the extension of the vegetative 

 stages of development, and the production of a large amount 

 of crude or unripened vegetable substance. 



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 64, and of lime in Table 

 65. 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 ele- 

 ments 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 



