Abstract
The occurrence of both epidermic browning and blackening of lotus rhizome makes its market value lower. To prevent them, it is necessary to understand the better conditions of the lotus field for the land consolidation works. Therefore, the relationship between Eh in the plow layer, and the occurrence of both epidermic browning and blackening were examined, considering the various factors which influence Eh in situ.
The results are as follows:
1) Both epidermic brown and black substance was consisted of iron.
2) The adhesion of both epidermic brown and black substance was recognized under the condition where the value of Eh is above-100 mV in the deeper part of plow layer. The higher Eh in the plow layer went up, the more the amount of its adhesion became.
3) Eh was low in summer, but it increased gradually from the upper part of plow layer with the falling of temperature in winter. Therefore, it is necessary to control Eh low enough to prevent the adhesion of epidermic substances, until the harvest season.
4) If compered rhizosphere soil among different sites at the same time, the adhesion of both epidermic brown and black substance was less as the content of free iron oxide was lower, and the content of soil organic matter was higher.
