132 BULLETIN OF THE BUSSEY INSTITUTION. 
with nitrogenous matters. Wherever the roots of the crop may turn, 
they are sure to find an abundance of this particular form of food ; . 
just as in land that has been permeated with soluble phosphoric acid - 
by the application of a true superphosphate, the plant can every- 
where find all the phosphates it can possibly use. It is easy to ex- 
plain in this way the high esteem in which dung is justly held. It 
must usually happen, at least as regards poor soils, that dung will 
have for this reason a certain superiority as manure over artificial 
mixtures of chemicals, unless, indeed, means are devised for con- 
trolling the fixation and diffusion of the nitrogenized chemicals, 
such as the ammonium salts and nitrates. Practically, good re- 
sults could be got, no doubt, by using sulphate of ammonia in the 
original mixture of fertilizers, and occasionally applying nitrate of 
soda afterwards. As is well known, the objection to the use of 
the nitrate by itself, or rather when applied all at once, is its too 
rapid rate of diffusion. The soil has little power to fix or hold it. 
Whatever part of it the crop cannot immediately put to use is quickly 
washed out of the land by rains. 
The opinion very generally held by farmers that, even as a mere 
question of fertilization, without regard to any advantage that may 
be gained by giving the food to cattle, it is generally speaking better 
to carry dung from the stable to the field than to plough under a green 
crop, or, in other words, the common prejudice in favor of manuring 
with dung, as such, rather than with the vegetable matters from 
which the dung has been produced, probably depends in good part 
upon the superior diffusive power of the nitrogenous constituents in 
the dung. The benefit derived from mere concentration of the fer- 
tilizing components, through the removal of the organic matters that 
are exhaled in the breath of the animals when vegetable substances 
are reduced to the state of dung, 
must be largely offset by the costs 
of transportation and of applying the dung, and a considerable 
amount of fertilizing material is necessarily lost during the process 
of concentration. 
