{ 6o ) 



5. SOILS OF MESOZOIC ORIGIN. 



Of the Mesozoic formations, the Trias system occupies a 

 very trifling area, next comes tlie Jurassic and finally the. 

 Cretaceous has the largest area. Arable soils are largely 

 found in the Cretaceoiis system. Phyllite, sandstone and 

 conglomerate contribute mainly to the production of soils. 



Soils derived from the Trias have a low absorptive 

 capacity but otherwise good physical properties. They are 

 moderately fertile and have proved good for rice fields; but 

 they have no importance for fruit trees in this country. 



The Jurassic soils have by far the greatest absorptive 

 capacity, and the physical properties appear to be generally 

 good. 



. The Cretaceous rocks mostly form gravelly loam, phyllite 

 and sandstone being the main source. About 25°/^ is very, 

 gravelly. The soils are very light and open, and are rich in 

 potash, but very poor in phosphoric acid. They are, however, 

 apl to dry up and be subject to drought. They are suited to 

 rice growing but valueless for fruits. 



6. TERTIARY SOILS. 



Soils of Tertiary origin occur over an extensive area, 

 being next to those of volcanic origin in the area they cover. 

 They are especially common in Hokkaido, north and north- 

 Vilest Japan. Most of these lands still remain in a virgin state. 

 The Tertiary soils of south Japan has already been cultivated. 



The Teriary lands have generally gentle elevations, 

 whilst the flat lands covering 48% of the. whole area are 

 available for agricultural purposes. 



The prevalent rocks of the Tertiary formations are 

 phyllite, tuffs and sandstone. They are rich in phosphoric 

 acid, potash, ^lumina and magnesia. Low-o.\idation product 

 of iron exists in the Tertiary soils of Hokkaido and north 



