EXPERIMENTS ON THE MIXED HERBAGE OF PERMANENT MEADOW. 347 
the whole period in the produce with the more potass applied is due to the greater 
amount taken up during the earlier years, when both plots were practically manured 
alike. In regard to the even lower amount with than without the potass over the 
later period, it should be observed that the potass-plot (9) has probably suffered at 
one end, for some years, from the roots of a large tree, but to what extent it is difficult 
to say. 
Ot mineral matter, on the other hand, about one-fifth less has been taken off, over 
the 14 years, in the crop grown without than with potass; and the falling off in 
amount, compared with the earlier period, is nearly 42 per cent, without, against only 
25 per cent, with, the potass. 
Thus, notwithstanding there was even rather more nitrogen annually taken up on 
plot 10 over the 14 years during which the potass was excluded from the manure, 
there was much less hay produced, and much less mineral matter taken up, than on 
plot 9, where the application of potass was continued. There was an average annual 
deficiency of more than 700 lbs. of hay, and of about 60 lbs. of mineral matter; the 
former representing a deficiency of carbon assimilated averaging about 230 lbs. per 
acre per annum in the removed produce, to say nothing of the second crops, the 
roots, &c. 
The deficiency of total growth on plot 10 compared with plot 9 was not manifested 
in any marked degree until after the first five years of the 14 ; in fact, during the 
first six years of the 20, a total of about 900 lbs. of potass per acre had been applied to 
each plot, and the total amount taken out in the crop was much less than this. It is 
to be supposed, therefore, that there was a considerable residue of the supplied potass 
possibly available for the succeeding crops. How much, however, it is impossible to 
decide absolutely; for, in the first place, we do not know whether as much, or more, 
or less, was given up from the soil itself in the presence of the liberal artificial 
supply than was taken up without manure, or by the ammonia-salts alone, or by the 
ammonia-salts and superphosphate of lime without potass or soda; nor, in the second 
place, do we know how much of the residue of the supplied potass would enter into 
such combinations within the soil as to remain either unavailable, or but slowly 
available to succeeding crops. 
If we assume, by way of illustration, and as as probable an estimate as we are able 
to make, that the soil of plot 10, during the six years when it received ammonia-salts 
and mixed mineral manure containing potass, yielded up to the growing crop the same 
quantity from its own stores as plot 4-2 during the first six years in which it received 
the same quantities of ammonia-salts and superphosphate of lime, but without potass 
or soda, then the residue of potass supplied during the six years to plot 10 would be 
about 412 lbs. at the end of that period. Yet, there was a very marked deficiency of 
potass taken up on plot 10 compared with plot 9 even in the first year of the discon¬ 
tinuance of the application. But there was, on the other hand, a very marked increase 
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