Rice production and weed suppression by combined application of jellyfish chips and rice bran

Abstract

During recent years, the number of jellyfish in the waters surrounding Japan has been increasing tremendously. Not only does this have a negative impact on the environment, but it is causing serious damage to the fisheries and coastal facilities. Jellyfish chips, i.e., desalted, dried, and shredded jellyfish, can act not only as an effective organic fertilizer, but also as a bioherbicide in paddy fields. However, we observed that following the application of jellyfish chips, the rice yield decreased by approximately 10% compared with that of conventional rice cultivation, and that weed control was insufficient and unstable. To overcome these limitations, we applied rice bran together with jellyfish chips, and compared the rice yield with that achieved by the conventional cultivation practice. The combined application of jellyfish chips and rice bran successfully controlled the weeds in the paddy fields providing a grain yield similar to that of conventional rice cultivation. The improvement in yield might be due to the difference in organic fertilizer composition and the onset time of fertilizer effect. Furthermore, the improvement in herbicidal effect can be attributed to the synergistic effect of different growth suppressing substances in the two organic fertilizers. Overall, the combined use of jellyfish chips and rice bran might be an innovative organic practice in paddy cultivation.