Farming without Live-stock. 
871 
1. A sufficient quantity of nutritive ingredients in an assimilable 
form. 
2. The maintenance or improvement of the physical properties of 
the soil by means of organic matter. 
Any question as to the first of these is already completely solved. 
In dung, the only chemical ingredients which need to be considered 
are nitrogen, phosphoric acid, and potash. The latter two are 
obtainable in the markets in all possible degrees of assimilability. 
A considerable variety of raw materials, or of by-products, which 
contain one or other of these two ingredients permits of gi-eat lati- 
tude in choosing the particular form in which each shall be applied. 
In the case of nitrogen, however, the problem is less simple. Although 
nitrates or salts of ammonia may always have been employed with 
success, at least upon soils of good quality, it is impossible to supply 
sandy or light soils with their nitrogen in an exclusively mineral 
form. The permeability of these soils is such that loss of nitrogen 
in the form of nitrates in the drainage waters cannot be avoided. 
Soils of this class are specially benefited by organic nitrogen, ' such as 
the nitrogen contained in the residues left by crops, or in leguminous 
plants specially cultivated for the purpose. For such soils, nitrogen 
offered in this form is preferable to that in chemical manures and 
even to that in the aramoniacal salts of dung, for in both cases nitrifi- 
cation proceeds too rapidly, and there is consequent loss through the 
medium of the waters that drain away from the soil. 
It appears therefore warrantable to assert that it is possible, 
without any ditEculty, to find substitutes for the nutritive ingre- 
dients of dung, and that the latter need no longer be regarded as 
indispensable ; also that it is further possible, at least upon soils sub- 
jected to a somewhat intensive treatment, to procure nitrogen by 
sideration (see page 874). 
On the other hand, it is less easy to dispense with the organic 
matters of dung. By oxidation these yield, first humates, and after- 
wards carbonic acid, the last-named discharging a very important 
function in connection with the assimilation of nutritive ingredients 
by plants. Its intervention is naturally the less called for the more 
assimilable the form in which the manures are added to the soil, so 
that, in such case, it would be possible to dispense with the presence 
of organic matter. But there is no compensation for the absence of 
the physical effect of organic matter upon the constitution of the soil; 
hence the application of organic matter is absolutely necessary. It so 
happens that it is precisely the plants, whose function it is to accu- 
mulate nitrogen, that produce at the same time an enormous quantity 
of carbonaceous matter ; moreover, even upon farms managed satis 
betail {i.e., without live-stock), there are usually working animals, so 
that in practice the employment of dung becomes largely diminished 
rather than completely suppressed. 
Hence it appears that cultivation by means of chemical fertilisers 
can be indefiiaitely continued only on the condition of supplying 
' Organic nitrogen is defined as nitrogen in organic combination with carbon 
