2 
RESEARCHES OH THE COMPOSITION 
soils. It is only with some of the former group that the 
following paper is intended to deal. 
The value of the direct fertilizers is dependent in the 
•first place, of course, upon their content of nitrogen, phos¬ 
phoric acid, and potash, but this is not their only value. 
The three vegetable nutrients must also exist in the ma¬ 
nures in a form in which they can be taken up by the roots. 
Of the nitrogen, for example, in the form of leather,, or of the 
phosphoric acid in the form of crushed rock phosphate the 
plants cannot much avail themselves, because in these 
materials the nutrients are so insoluble, and resistible to the 
decomposition in the soil, that their effect on the crops is 
hardly perceptible, or at least very slow. Thus, the solubil¬ 
ity of the nutrients, resp. the ease with which the manures 
decompose in the soil, is a second important point in the 
determination of their value. 
As already explained in No. 3 of the Bulletins of this 
College with reference to ordinary fertilizers of animal or 
vegetable origin, we shall not commit any serious error, if 
we assume in this country for the relative money value of 
nitrogen, phosphoric acid, and potash the proportion 5: 2: 1, 
e. g. if the value of a certain weight of nitrogen is 5, that 
of the same quantity of phosphoric acid is only 2, and of 
potash only 1. With the help of these figures it is easy to 
compare the costs and real value of several fertilizers and to 
find out which of them is cheapest. The following ex¬ 
ample, in which it is assumed that 100 kmvamme of tea seed 
cakes cost 3.50 yen, the same weight of wax berry cakes 
(kaji dama) 1.50 yen, will illustrate this. 
] 00 p. of wax berry cakes contain : 
Nitrogen . .1.16; multiplied by the factor 5 = 5.80 
Phosphoric acid. 0.42; „ „ ,, ,, 2=0.84 
Potash . 0.77; „ „ „ „ 1=0.77 
Sum of the manurial units. 7.41 
