212 
An Unwelcome Truth. 
[April, 
a field was, to begin with, thoroughly analysed. The field 
was then divided into plots ; certain of these were plenti- 
fully dressed with farmyard manure, others with sulphate of 
ammonia or soda saltpetre, whilst others, again, remained 
unmanured. All these three kinds of plots were planted 
with maize and potatoes for seven years in succession, and 
at the end of the last season the results were made known. 
In what state was the soil of these experimental plots ? 
Had this question been submitted to an agricultural che- 
mist of the year 1850, he would doubtless have replied that 
the unmanured portions of land would be found decidedly 
impoverished, whilst the manured portions would — at least 
as far as combined nitrogen is concerned — have become no 
poorer, or, if the supply had been sufficiently plentiful, might 
even have been enriched. As early as 1878 it was found 
that the loss to the soil was very much greater than would 
follow from the combined nitrogen carried away in the crops. 
Not merely the unmanured plots, but those which had re- 
ceived sulphate of ammonia and soda saltpetre were found 
distinctly impoverished. Those plots, on the other hand, 
which had been dressed with farmyard manure had grown 
somewhat richer. But it must be distinctly understood that 
they also had not retained the entire supply of nitrogen over 
and above that consumed by the crop. Hence it would ap- 
pear that if nitrogen is supplied to the land in a readily 
soluble form, as in the salts above mentioned, a very consi- 
derable proportion is lost. It dissolves in the rain-water, 
soaks down into the drains, and passes away into the rivers. 
But M. Deherain draws from his experiments a further 
conclusion — the more plentiful the manuring the greater is 
the loss. This appears from the faCt that from 1878 to 1881 
the cultivation of maize was continued, but wheat was grown 
instead of potatoes, and the supply of manures was brought 
to an end. The crops were weighed yearly as before, and 
the soil was analysed in the year 1881. A loss of combined 
nitrogen was still apparent, greater in quantity than that 
consumed by and carried off in the crops. But the yearly 
loss was smaller than it had been during the years of copious 
manuring. 
A third point which became apparent, though perfectly in 
accordance with known chemical laws, is equally unwel- 
come. These losses of nitrogen ceased when the land was 
no longer subject to yearly cultivation, but was converted 
into an artificial meadow. From 1875 to 1879 a series of 
plots had been yearly planted with beets, and in the last 
year the soil, on analysis, was found to be impoverished to 
