An Unwelcome Truth . 
213 
1883.] 
a noteworthy degree. Then sainfoin was substituted for the 
beets, and, although no manure was given and three good 
crops were taken off, the soil was found in 1881 to be not 
only not impoverished, but slightly enriched. 
M. Deherain infers that the method of cultivation adopted 
has a greater influence upon the richness of the soil than 
the manure supplied and the crops taken away. The expe- 
riments conduced at Grignon lead to this significant result 
— arable land in constant, regular cultivation, cannot be en- 
riched by large applications of soluble manures. The 
improvement which is produced by farmyard manure — and 
consequently by other less readily soluble manurial matters, 
such as fish, dried blood, powdered horns and hoofs — is but 
transitory, and soon disappears if the soil is broken up and 
disturbed every year by the work of the plough. If the soil 
is left undisturbed it does not become impoverished, although 
yielding abundant crops. 
These fadts not merely agree with the results of other in- 
vestigators, — I may especially mention Messrs. Lawes and 
Gilbert, — but are readily intelligible if we consider the effedts 
of cultivation. The more the soil is broken up by the plough 
or the spade, the more pervious it becomes to air and water. 
In consequence nitrogenous bodies are quickly decomposed, 
and their nitrogen, under the oxidising adtion of the air, 
assumes the state of nitrates. These nitrates, being readily 
soluble, are dissolved by every shower of rain, and carried 
away as already explained. 
This view of the case is simply alarming, and necessitates 
the question — How can a progressive deterioration of the 
soil, leading to ultimate sterility, be avoided or retarded ? 
The circumstance which M. Deherain mentions, that the 
impoverishment of the soil is arrrested if it is let alone, is, 
as a consolation, perfedtly nugatory. The crops of which 
human food consists — at least in all the colder parts of the 
earth — are annual, and require a yearly ploughing. I need 
only mention all the kinds of corn, potatoes and other escu- 
lent roots, and the leguminous plants and herbs of the 
cabbage tribe. We cannot subsist upon the produce of 
orchards, both because of its precarious nature, and because 
during a great part of the year it necessarily fails us. 
Pasturage and meadows, natural or artificial, do not meet 
the difficulty. A scanty population may indeed be supported 
on meat, milk, and other animal products ; but as a country 
becomes more civilised and more densely inhabited, the 
relative number of cattle and sheep necessarily decreases, 
and the people are more and more driven to a vegetable 
