20 
IMPERIAL COLLEGE OF 
We may now turn to the discussion of the fertilizing 
properties of human excreta. Compared with other manures 
the night-soil is, as the analyses given on p. 4 and 5 show, 
very poor in organic substance in relation to its contents in 
nitrogen. In all those cases in which the porosity of the 
soil is deficient and an increase of the humus is needed, 
excreta cannot consequently constitute the only manure 
for many years, but must be supplemented with vegetable 
materials, such as straw, chaff, leaves, grasses, seaweeds, 
etc., with which they are best made into compost. Fur¬ 
thermore, owing to their richness in easily soluble am¬ 
moniacal salts their effect on sandy not well decomposed 
soils, which are so frequent in Japan, will likewise not 
attain the degree to be expected from their richness in 
vegetable nutrients, because these soils have not the power 
of protecting the fertilizing ingredients from being washed 
down deep into the subsoil by the rains so frequent in this 
country. For these soils composted vegetable matters are 
preferable unless the farmer possesses the skill and time to 
nurse up the crops so to say, by frequent applications of 
well diluted dung. Only where the farms are small, and 
the working power is superfluous, this practice promises 
success, though not with the same certainty as when an 
appropriate quantity of slowly decaying vegetable manure 
is applied, which yields a slow but sufficient flow of nitro¬ 
gen throughout the period of growth, and does no harm in 
times of drought. 
In order to ascertain how far the relative proportion 
of the nutrients of the excreta coincides with the needs of 
the crops, we may first calculate the maximum produce that 
can be obtained from the nitrogen of 1000 liters of night- 
soil, provided that all other nutrients exist in the field 
in suitable and sufficient proportions and that the other 
conditions for a normal growth, such as light, heat, and 
moisture, are favourable. As under suitable circum- 
