THE PROPER SEASON FOR APPLICATION OF FERTILIZERS TO 



SUGI (Criptomeria japonica) AND HINOKI (Chamaecyparis obtusa) 

 SEEDLINGS AND THE EFFICACY OF FERTIl IZERS 



By SHIGEMASA NORIYA, Chemist of Forest Fxperiment Station 



Sugi and Hinoki are known as the principal forest trees of the 

 country, and the supply of sound seedlings of these trees is indeed an 

 important part of the work of forestry. Accurate investigations of 

 fertilizers and of the proper time for their applications so as to bring 

 about the best results are of the greatest importance. 



Although the efficacy of nitrogenous manures on farm crops has 

 already been established by a series of trials by different authorities ; little 

 is known on the manurial value of these fertilizers for forest tree seedlings. 

 To fill the gap, thus left, the author has occupied since 1911 in determining 

 the efficacy and the proper time for applying nitrogenous manures to 

 forest tree seedlings and the results obtained therefrom are as follows. 



I. Method of Experiment 



(1) Soil used for the Trial: — Loamy soil in the Forest Experiment 

 Station, Tokyo. It was rich in humus where Keyaki (Zelkowa acuminata) 

 seedlings had been raised and where no manure had been used for the 

 preceding 7 — 8 years. 



The composition of the air-dried soil was a follows: — 



Water (H,0) 10.457 



Loss by ignition 20.850 



Humus 5.935 



Total nitrogen 0.327 



Residue insoluble in HCl 49.332 



Silica soluble in HCl 0.722 



Silica soluble in Sodium Carbonate 21.905 



Sum of Silica 22.627 



Alumina (AI2O3) 12.827 



Ferric oxide (FesO,) 10.570 



