"Nieda" at Kujukuri Sea Coast and Its Technical Improvement (Preliminary report)

[摘要] Deteriorated paddy fields of a peculiar type popularly known as Nieda exist widely in the districts of Kujukuri Coast, Chiba Prefecture, where abnormal retardation in the rice plant growth usually takes place early in mid-summer. The results of the authors investigations of the phenomena are as follows : 1) The surface of Nieda was covered by a sort of viscid mud, and water percolation was so poor that there were proved various products of soil reduction such as ferrous compounds, hydrogen sulfide and organic acids generally injurious to the plant accumulating and gradually being concentrated around the roots. 2) A symptom like Akagare was frequently observed on the rice plants grown in Nieda. True Akagare, however, is generally known as a symptom of potassium deficiency. As the plant cultured with Nieda soil was proved to have absorbed potassium normally, the symptom above mentioned should not directly be ascribed to potassium lack. 3) According to the results of the author's studies, the injury was supposed to be attributable to disturbance of normal aerobic respiration induced by absorption of ferrous compounds under the peculiar soil conditions, because the plants in Nieda were found to accumulate in their bodies abnormally large amounts of ferrous compounds. It was demonstrated, in fact, that Nieda soils could be improved very remakably by removing the viscid mud from their sufaces by means of supplying MgCl2 or by admixing with red-colored hill soils.

[学科分类] 农业科学（综合）