Rotation of Crops. 
627 
grown crops were annually manured with superphosphate, 
whilst for those grown in rotation the application had only been 
for the preceding crop — the turnips. The less assimilation in 
the case of the continuous crops was doubtless due to the 
diminished total growth, which in its turn was due to the 
greater exhaustion of the available nitrogen of the soil with the 
annual growth. Consistently with this view, where the mixed 
manure supplying an abundance of nitrogen was applied, 
and the crops, both rotation and continuous, were pretty full 
averages for the particular soil and the seasons of growth, 
the amounts of phosphoric acid in the rotation crops where 
the roots had not been removed were almost identical with 
those in the continuous crops. Where, however, the rotation 
roots had been removed, carrying off therefore the whole of the 
nitrogen that had been taken up, the succeeding barley crops 
were accordingly not full for the seasons of their growth, and 
the amounts of phosphoric acid in them were less than in the 
continuously grown crops. 
The figures relating to both the rotation and the continuous 
barley further show, that about six-sevenths of the total phos- 
phoric acid of the crops is accumulated in the grain which is 
supposed to be sold off the farm. There was, indeed, even a some- 
what higher proportion where phosphoric acid was supplied in 
the manure. Lastly, as in the cases of the total produce, the 
dry matter, and the nitrogen, there is much less difference be- 
tween the amounts of phosphoric acid taken up under the three 
different conditions as to manuring than in the case of the 
turnips. That is, the assumed restorative crop is much more 
dependent on direct manuring to yield any crop at all than is 
the cereal crop, which is assumed to be benefited by the inter- 
polation of it. 
The Phosphoric Acid in the Leguminous Crops . — Referring 
to the third division of Table VIII., it is seen that the 
amounts of phosphoric acid in the total produce of beans, 
corn and straw together, was more where superphosphate 
was supplied than without manure, and more still under the 
influence of the mixed manure containing, besides superphos- 
phate, salts of potash, soda, and magnesia, and nitrogen also. 
But, under all three conditions as to manuring, the continuously 
grown crops take up much less than those grown in rotation. 
Whether, however, grown in rotation or continuously, three, four, 
or more times, as much of the phosphoric acid is finally accu- 
mulated in the corn as remains in the straw. In reference to 
all the results with beans, however, it is to be borne in mind 
that under none of the conditions were good crops obtained. 
