244 



THE EOTHAMSTED EXPERIMENTS. 



Other min- 

 eral con- 

 stituents. 



when the growing crops had to rely for their potash exclu- 

 sively on the stores of the soil itself, the rotation crops took 

 up about twice as much as the continuous. Lastly, with the 

 mixed manure supplying potash, the rotation wheat crops 

 gathered nearly 36 lb. after fallow, but about 38 lb. after 

 the leguminous crops ; whilst the continuously grown ones 

 yielded an average of only about 27 lb. That is, although 

 in the case of the rotation wheat crops three other crops had 

 been grown since the application of the manure, they took 

 up more potash than the continuously grown ones for which 

 potash was annually supplied. 



So much for the results relating to the amounts of the two 

 important and typical mineral constituents — phosphoric acid 

 and potash — taken up by the different crops when grown, 

 respectively, in rotation and continuously, under different con- 

 ditions as to manuring, and other treatment. Similar results 

 relating to other mineral constituents of the crops have been 

 got out, and the discussion of some of them brings to view 

 points of considerable interest, but neither time nor space 

 will admit of their consideration here. It must suffice to 

 refer briefly to the amounts of lime taken up by the legu- 

 minous crops under different conditions ; a point which has 

 an interesting relation to the results as to the potash taken 

 up by those crops, and to the questions which arose in the 

 discussion of them. 



Lime in 

 corn and 

 straw of 

 leans. 



Rotation 

 and contin- 

 uous crops. 



The Amounts of Lime in the Rotation, and in the Continuous 

 Leguminous Crops. 



The following Table (65) gives, for the leguminous crops 

 alone, the amounts of lime in the rotation and in the con- 

 tinuous crops, in the same form in which the phosphoric 

 acid and potash have been given for each of the four crops 

 of the rotation. 



Very different from what was found to be the case with 

 the potash, it is seen that in the rotation bean-crops a very 

 small proportion of the total amount of lime is accumulated 

 in the corn ; ten, twelve, or more times as much being found 

 in the straw. Then, the amounts of lime in the total crops 

 were — without manure between 15 and 16 lb. ; with super- 

 phosphate, which of course supplied some lime, the quantity 

 was raised to 18.68 and 20.71 lb. ; and with the mixed 

 manure, also supplying the same amount of lime in its super- 

 phosphate, it was further raised to 26.57 and 27.71 lb. It is 

 further seen, that the continuously grown beans contained — 

 in corn, straw, and total produce — in some cases only about, 



