THE USE OF FRESH MANURE. 63 
is much less readily available to plants than has been 
generally supposed. If the availability of the nitrogen of 
nitrates be taken as too, that of the nitrogen of well- 
rotted manure was only 45 per cent. Kiihn has found, 
on the other hand, that the nitrogen of fresh cattle dung 
is very readily available. If the availability of the nitro- 
gen of sulphate of ammonia be taken as too, that of fresh 
manure was g2 per cent. Wagner further observed that 
fresh manure has a decided tendency to liberate the ni- 
trogen of nitrates or of green manures, so “that the in- 
crease of crops secured by the horse dung and nitrates, 
etc., together, may be less than is produced by the ni- 
trates, etc.,; alone.” 
‘It appears that soils, to which were added three grams 
of nitrogen; viz., two grams in form of fresh horse dung 
and one gram in form of nitrate of soda, yielded a very 
considerably smaller crop than the same soil to which 
one gram of nitrate nitrogen was added without dung. 
This, according to Wagner, is explained by the fact that 
the microbes in the fresh dung expelled nitrogen in the 
gaseous form, both from the dung itself and from the 
nitrate, before vegetation could assimilate it. 
‘‘While the horse dung applied in Wagner’s trials was 
fresh and the quantities were much larger than are ordi- 
narily used in farm practice, yet the facts above cited 
have a very important bearing on the use of fresh stable 
manure and possibly on the value of composts, such as 
are used for forcing-house soil, in which the proportion 
of stable manure is approximately near to that which was 
used in Wagner’s tests, where a large loss of nitrogen was 
observed. It might, therefore, happen that applications 
of nitrates or other nitrogenous fertilizers to the soil of 
the forcing-house would have no marked effect on the 
crop, while nevertheless available nitrogen was deficient 
and the crop suffering in consequence. This result might 
at least be expected to follow the use of fresh manure 
water.”’ 
