870 
FARMING WITHOUT LIVE-STOCK.' 
It is hardly necessary to go back far into the history of agriculture 
in order to encounter the belief, formerly undisputed, that the use 
of dung is an indispensable condition in the maintenance of the 
fertility of the soil. Farmyard manure was regarded as the source 
of all fertility, because it was held to contain a certain principle 
which cultivated soils lost in the process of time. In order to con- 
ceive the possibility of preserving, and even of increasing, the fertility 
of the soil without the intervention of dung, some knowledge of 
the laws of the nutrition of plants was indispensable. Liebig 
enunciated the principle that the action of manure was due to the 
presence of certain ingredients, of which chemical analysis served to 
indicate both the nature and the quantity. But he failed to make 
the progress he otherwise would have done because he did not ade- 
quately grasp the importance of the nitrogenous ingredients, for 
he held the view that all plants draw their nitrogen from the air. 
Subsequently it became recognised that the physical constitution of 
soils underwent some modification when year by year they were 
dressed exclusively with mineral manures, and that dung embodied, 
over and above its directly nutritive ingredients, a substance capable 
of maintaining in a desirable condition the physical properties of 
soils. This substance is the organic matter, which, by a series of 
changes, yields humic compounds.. 
What happens when these compounds are lacking in a soil has 
been experimentally demonstrated by M. von Zimmerman, upon his 
celebrated farm at Benkendorf, Saxony. A field was selected upon 
loamy soil, and the following rotation was practised, the object being 
to leave in the soil as little plant refuse as possible : — (I) Peas 
or potatoes ; (2) wheat (square-head) ; (3) sugar-beet j (4) wheat 
(Eivett's bearded) ; (5) sugar-beet ; (6) barley. For a period of 
thirty years this field received none but chemical manures, and the 
crops yielded almost as well as those grown upon adjoining land. 
But the loamy soil, which, at the outset, was free-working and of 
medium consistency, became extraordinarily difficult to work. So 
much was this the case that the usual tillage operations proved 
ineffective, and it became necessary to resort to special means. 
The conditions, however, are not entirely the same in the XDase of 
sandy soils, in which the plants suffer from lack of cohesion amongst 
the particles. It has long been known that humus imparts cohesion 
to light soils, whilst it i-enders heavy soils more open. 
The substances which enter into the formation of humus are 
capable of being added to the soil either in the form of manure, or 
of vegetable refuse, the latter consisting either of the residues of 
crops left in the soil or of green manures. Hence the needs of a 
cultivated soil may be said to embrace : — 
' Zes Fermeg gam BHa\l en AUeviagne, par M. de Malliard, chargfi 
d'une mission agricole spfcialc. 
