Studies on the Nutrition of the Rice Plant with Reference to the Occurrence of the So-called "Akagare" Disease. : II. Influence of the Supply of Organic Acid and Hydrogen Sulphide to the Soil upon the Occurrence of the Disease.

Nutritional Disorders of the Rice Plant in Asia

“…Exchangeable cations are generally very low. Exchangeable calcium is low, ranging from 1.4 to 3.6 meq/100 g soil; exchangeable magnesium is low except soils of marine alluvium (Sites 1, 5, 12); exchangeable potassium is extremely low except Site 12; and exchangeable sodium is also low except the soils with marine influence (Sites 1,5,11,12).…”

“…Nowadays, Akiochi has been almost overcome. Akagrre ( 10,12,13,14,16,17,18,19,50,74,102,106,107,112,113,137,138 ) Aka-gare literally means red-withering. It appears 2 or 3 weeks after transplanting and the main symptom is the appearance of reddish-brown spots on the older leaves of the plant.…”

“…Mountains or hills are thinly covered with pine trees, indicating a poor nutrient supply in soils. Soils of the rice fields are mostly river alluvium but, in some areas, they are derived from marine alluvium ( Sites 1,5,11,12,13). They are generally sandy or silty, but some (Sites 12, 13) are rather clayey with poor permeability.…”