MANURING EXPERIMENTS WITH PADDY RICE (SECOND YEAR). 
39 
The proportion of nitrogen consumed from the manure is, 
according to these figures very considerable, largely excceeding 
the quantities taken up from the manures applied on dry land. 
On the latter, researches reported in bulletin No. 6 (p.31), have 
shown that from 100 parts of nitrogen applied there was 
consumed by barley: 
from night-soil . 41 % 
,, ammonium sulphate. 40 ,, 
,, fish manure. 47 ,, 
,, steamed bone dust . 55 ,, 
Barley, it is true, has shorter roots than rice, and feeds 
chiefly on the surface soil, but other deep-rooted cereals, like 
wheat, are also incapable of consuming such high rates of 
nitrogen as rice does in irrigated land. The rapid process of 
nitrification in dry soils converts the decomposable nitrogenous 
compounds too speedily into nitrates which cannot be retained 
by the soil but are washed down beyond the range of the roots, 
and thus escape consumption by the plants ; whereas in paddy 
soils, while they are being irrigated, nitrates are not formed, 
but ammonia is the final product of decay which is strongly 
retained in most soils, thus admitting of a more complete 
utilization by the plants. The economy of manures is accor¬ 
dingly greater in paddy fields than on dry land. 
As to the rate of the consumption of nitrogen from the various 
fertilizers, we notice in our experiments marked differences. 
In harmony with the effect on the yield the largest proportions 
of nitrogen (80%) are consumed from the easily decomposable 
manures of purely animal origin (steamed bone dust, fish 
manure, dried powdered blood) ; next come crude bone dust, 
shöchü cake, horn meal, and Peruvian guano, with an “ asssimi- 
lation-factor,” as we may call it, of 72%; a little less decom¬ 
posable are the rape cake and the shöyu cake, for which a 
preparatory treatment in the compost bed is advisable also in 
view of this result ; night-soil yields a little more nitrogen (66%) 
to the rice than ammonium sulphate, for which in this season 
very nearly the same assimilation-factor (61.4) was found as in 
