44 
THIRTEENTH REPORT. 
siderable accuracy the amount of nitrogen in these forms. In the samples 
of peat already worked with, the amount of amino nitrogen after boil- 
ing with acid has been from 30-35% of the total nitrogen. Only traces 
of amino nitrogen are found in peat as such. 
These compounds necessarily occur in soils in small quantities, and 
their separation is accomplished only after the most careful and pains- 
taking work. But it is confidently expected that now since the way has 
been fairly well paved more investigators will be tempted to enter this 
field of research and more of these compounds will be isolated from soils. 
Certain it is that with a more complete knowledge of the composition 
of the organic matter of soils one will be able to predict more definitely 
in regard to the possible availability of some of the plant-food elements 
in combination with it. 
The relation of the soil phosphorus to the organic matter is perhaps 
less understood todav than is the case with nitrogen. There has been a 
great diversity of opinion as to the existence, even of phosphorus in 
combination with organic matter. As early as 1844 Mulder observed 
that the organic matter was not readily freed from phosphorus. 
Grandeau believed that the phosphorus associated with the extracted 
matiere noire to be an index of the fertility of the soil. Eichorn con- 
cluded that the phosphorus does not form organic combination. Some ex- 
perimenters believed that the phosphorus was held in the organic matter 
bv absorption. V an Bemmelen supported this theory and he suggested 
that a part of the phosphorus occurred in the form of a “colloidal humus- 
silicate complex.” 
Schmoeger reviewing the work of his predecessors concluded that the 
phosphorus did not exist as absorbed phosphorus but that it was present 
in organic combination. Tie found lecithin to be present in traces and 
was led to believe that nuclein or some closely allied bodies were present. 
Aso confirmed in a general way, the results obtained by Schmoeger. He 
drew the following conclusions: 
1. “Phosphorus exists in the soil as inorganic and organic com- 
pounds.” 
2. “The organic phosphorus materials is principally nuclein with a 
small part of lecithin.” 
3. Ignition rendered the phosphorus in organic combination avail- 
able.” 
More recently Schreiner and Shorev have demonstrated the fact that 
phosphorus does exist in the soil in organic combination by isolating 
several compounds known to be decomposition products of nucleo- 
proteids. Beyond the fact that the presence of organic matter in the soil 
improves its combination and also increases its productive capacity we 
know but little of the value of any of these specific compounds as pos- 
sible sources of plant food. We know there are some organic compounds 
in the soil that are harmful and we need to know more in regard to the 
most .practical means of counteracting them. 
The manner of conducting fertilizer tests by measuring the crop pro- 
duced has failed to materially increase our knowledge of soil conditions 
and it is now quite generally recognized that it is unsafe to draw general 
conclusions from results based on such experiments. If we accept the 
dynamic theory of soils, that is, that they are continually changing and 
that no two soils are alike, we must inevitably come to this conclusion. 
