The improvement of rice cultivation on badly drained fields. I. Chemical characteristics of akagare paddy soils and their classification with reference to the occurrence of the disease. 2. Effects of reducing conditions in the soil on the occurrence of the disease. 3. Effect of supplying hydrogen sulphide, butyric acid and ferrous compounds in culture solutions on plant growth.
Yamaguchi, H.; Shiratori, K.; Koizumi, A.
Proc. Crop Sci. Soc, Japan 26: 3-7
Low K content, abundant humus, shortage of ferric compounds in the topsoil, excess NH3, O2deficiency, low Eh, and the presence of organic acids, ferrous compounds or H2S promoted the disease. 13 different types of "akagare" soil were distinguished. Covering the soil surface with olive oil during tillering resulted in "akagare" symptoms and low plant K/N ratios; covering the soil during the period between ear formation and heading caused no symptoms.