268 
Desirable A<jricuUural Exjjeriments. 
investigators has been tested and confirmed by the highest 
English authorities, and has been all the more readily accepted 
because it is entirely in accord with the results of ordinary 
farming experience. That leguminous plants not only flourished 
without being supplied by man with what we now distinguish 
as nitrogenous manure, but also in some way enriched the soil 
for the succeeding crop, is a fact which has been familiar to 
farmers ever since agriculture became a system ; but the reason 
has been only recently established beyond dispute. 
It is not necessary on the present occasion to inquire whether 
the precise modus operandi has been also distinctly established — 
whether, for instance, the evidence as to the agency of root 
nodules or of the microbes associated with them will stand the 
test of time. It is enough for the present to know that, in 
some way, leguminous plants are enabled to derive all the 
nitrogen they require from the atmosphere. The further ques- 
tion as to whether certain foreign chemists are justified in their 
assertion that other plants than those belonging to the natural 
order Leguminosse also assimilate the nitrogen of the air must 
be left to specialists to investigate. The assertion is said to be 
supported by the results of recent experiments carried out by a 
high authority in Germany ; but, apart from the fact that it is 
not in accordance with the apparent teachings of ordinary 
farming experience, its examination requires the elaborate and 
precise methods of the scientific expert, and cannot therefore be 
recommended as a subject for ordinary field trials. What I 
have now to propose is a set of co-operative trials by different 
agricultural associations for the purpose of ascertaining how the 
discovery in relation to leguminous crops can be best applied to 
farm practice. 
In the first place farmers need to ascertain whether it will 
answer their purpose to modify their usual rotation of cropping, 
or their method of disposing of some of their crops, in order to 
levy a tax upon the practically boundless wealth of nitrogen in 
the atmosphere. At first sight there is something exceedingly 
attractive in the idea of free nitrogen, that element of fertility 
being at once the most essential and the most costly of all 
plant-foods. The question is, however, whether a sufficient 
supply of atmospheric nitrogen can be obtained free of expense; 
or, if it costs something, whether and in what way it can be 
obtained at less expense than is incurred under the present 
general methods of supplying nitrogen to land. Under an 
ordinary rotation of cropping a limited levy upon the nitrogen 
of the atmosphere is clearly made without expense, because the 
clover crop at least — to say nothing of other leguminous crops 
