94 BULLETIN OF THE BUSSEY INSTITUTION. 
Next to the good effects produced by the potassic manures, the bad 
results obtained by the use of bone-dust, in Sections C and CC, are — 
specially noteworthy. I had been so often assured by experienced per- 
sons, before these experiments were begun, that bone-dust, particularly 
in dry seasons, often produces very little useful effect upon our drift 
soils, that it was no matter for surprise to see the phosphatic manures 
fail in most instances. But I was not prepared for the actual harm 
that seems to have been done by these manures in several cases, 
Since this report was written, I have noticed* that Professor May 
of the agricultural school at Bayreuth has likewise observed that some 
of the phosphatic manures employed by him in a set of field experi- 
ments were not only useless, but distinctly prejudicial to the growth 
of wheat and barley. 
So few methodical field experiments have been made hitherto upon 
very poor soils that it is no great wonder that the tendency of the. 
phosphates to hurt a struggling crop should have been overlooked. I 
have tried a number of experiments in pots, with the view of deter- 
mining how large an amount of phosphatic manure may be safely 
applied to sterile land, and from the results already obtained it would 
seem that bone-dust and other phosphates, when present in too large 
quantity, may exert an exceedingly hurtful influence upon the devel- 
opment of the plumule or first sprout that springs from the seed, 
especially at the time when the young shoot is ceasing to draw nour- 
ishment from the seed, and is beginning to live upon matters derived 
from the soil and from the air. It would seem that the seedling can- 
not endure the presence of a certain excess of phosphate of lime, — at 
least when the soil in which it stands is too poor to supply at once all 
the food that the plant may need. If too much of the phosphate 
should happen to come in contact with a seed, the young plant that 
springs therefrom is liable to perish almost at its birth, or to suffer so- 
severely in the struggle to gain an independent foothold on the soil 
that it remains weak and stunted for a long time. It may yet be 
found that one advantage in using superphosphate of lime as a fertilizer 
consists in the ability of the soluble phosphoric acid that is contained 
in that substance to get out of the way of the young plants ; that is 
to say, to diffuse itself so thoroughly in the soil that no hurtful excess 
of an active phosphate can be anywhere encountered by their roots. 
* In Biedermann’s Central-Blatt fiir Agrikulturchemie, October, 1872, 2. 204. 
