Agriculture Reference
In-Depth Information
The eye, after wandering through the glades of the forest, and resting on the brown
carpeting of fern and heather with which it is clothed, is amazed on coming suddenly
in view of the rich green of the meadows, extended for miles before it, laid in gentle
slopes and artificial terraces, and preserved in perpetual verdure by supplies of water
continually thrown over their surface.
16
A century later, André Voisin described a similar system in the valley of the Elorn, in
Brittany:
Each peasant in this valley owns a small acreage of grass which he irrigates reg-
ularly with water from the River Elorn; this is charged with the waste from the tan-
neries and the rich sewage from the town of Landivisiau [population in 2007 8,000],
which dominates that part of the valley. The grass is mown to be carried in and fed to
the animals in the stall. In this way they succeed in obtaining eight or nine rotations.
In winter they are aided by the fact that the water of the Elorn is higher than that of
neighbouring rivers. According to the information collected (roughly estimated as it
was) the peasants of the Elorn valley harvest per annum more than 120 tonnes of grass
per hectare.
17
There was an obvious health advantage in applying the effluent to grass, which was not
immediately consumed by humans, in contrast to Chinese night soil which was directly ap-
plied to crops, and was probably responsible for high death rates from dysentery, typhoid
minimize leaching of nitrogen - though the method of transmitting the effluent from the
town was far from ideal.
However, during the second half of the 19th century most of these schemes began to fall
into disuse as the shortfall in soil nutrients was plugged, not initially by chemical fertilizers
but by the importation of vast amounts of guano - the accumulated droppings of genera-
tions of seabirds on distant islands. Phosphate was quarried abroad and also became avail-
able as a byproduct of the steel industry (basic slag). Fertility (like most other commodities
during the 19th century) was being mined in the four quarters of the world and imported
in massive concentrations to the island that was the fount of industrial civilization, and that
included industrial agriculture.
But while the phosphate quarries were still producing, the supply of guano could not last
forever, and in 1909 an economic process for manufacturing nitrogen fertilizers from the
atmosphere was invented in 1909 by another German, Fritz Haber - a man who might have
become as great a hero in the annals of science as Liebig if he hadn't gone on to invent
