EXPERIMENTS ON THE MIXED HERBAGE OE PERMANENT MEADOW. 315 
than that without manure. On the other hand, the superphosphate alone gave, over 
the total period of 17 years, less than two-thirds as much hay as the mixed mineral 
manure. 
Of nitrogen, again, the increase by the superphosphate was insignificant, and both 
it and the actual yield declined considerably over the later period. The average 
annual yield of it over the 17 years was 23 lbs. less than, and did not amount to 
three-fifths as much as, by the mixed mineral manure. 
Of mineral matter taken up, the increased amount was proportionally greater than 
that of either the hay or the nitrogen ; but here, again, both the actual yield and the 
increase declined considerably over the later years. But the quantity taken up was 
much less, and decreased as the experiment proceeded, compared with that yielded by 
the mixed mineral manured plot. 
The result is, that the percentage reduction in annual yield of hay, of nitrogen, and 
of mineral matter, over the second period compared with the first, was greater with 
the superphosphate than without manure; whilst with the mixed mineral manure 
there was, instead of a reduction, an increase of all three over the second period. 
The botany of the plot was comparatively little affected by the superphosphate of 
lime. The number and the relative predominance of species were much the same as 
without manure. Perhaps the most characteristic changes were a rather greater 
weight of total gramineous herbage, due mainly to more of ripening tendency ; a 
reduction in weight of Leguminosse, with a prevalence of Lathyrus pratensis rather 
than of Lotus corniculatus; and an increase in weight of miscellaneous herbage, with 
a greater prevalence especially of Ranunculus repens and bulbosus, Achillea millefolium 
and Rumex acetosa. 
Of the constituents supplied in the superphosphate of lime, a little more of lime 
and magnesia, one-and-a-half time as much sulphuric acid, and nearly twice as much 
phosphoric acid, were taken up under its influence as without manure. Of con¬ 
stituents not supplied in the manure, but derived from the soil itself, there was of 
potass and silica very little more taken up than without manure, but the increase of 
soda was somewhat greater. There was a decline in the amount taken up of every 
one of the mineral constituents over the second period ; and this was proportionally 
the greatest with the soda, the silica, and the sulphuric acid, and greater in the 
magnesia than in either the potass or the lime. 
It would appear that the superphosphate had enabled the plants to draw somewhat 
more largely on the resources of the soil, especially in the earlier years, but that the 
small increased available supply under its influence was rapidly diminishing. Lastly, 
the comparison of the produce by the superphosphate of lime alone, with that by the 
mixed mineral manure, clearly shows that it was neither exclusively, nor even mainly, 
to the phosphoric acid which the latter contained that the results it yielded were due. 
2 s 2 
