[P2] Farming System

[P2-03] Growth and Yield of Rice, and Soil Enzyme Activites in Super Low External-Input Paddy Rice Field

*Nominated for Presentation Awards

^○Taichi Tsujimoto¹, Kazuhiro Hosoya¹, Hideto Ueno¹, Yo Toma¹, Yoichi Yamashita², Masataka Adachi², Takayuki Kono² (1.Graduate School of Agriculture, Ehime University, Japan, 2.Faculty of Agriculture, Ehime University, Japan)

Sustainable crop production has been required worldwide against resource depletion and environmental pollution. We have been cultivated paddy rice only with white clover as green manure for more than 10 years. In this study, we investigated the dynamics of nutrients and enzyme activities in the soil as well as the growth and of rice to clarify the mechanism of this cultivation system.In 2018, three rice varieties, Koshihikari (Oryza sativaL. cv. Kosihikari), Akitakomachi, and Matsuyamamii were cultivated. The green manure (GM) plot was applied with only white clover incorporation, and that in the control (C) was applied with a slow-release chemical fertilizer at 4.2:4.2:4.2 g m^-2 (N:P₂O₅:K₂O).There was no significant difference in the yield the both polts had around 400g m^-2, comparable to the local farmer's yield. Taste quality index were 70 or more in all plots. Soil available N decreased until mid-drying and then increased. On the whole GM kept 30 mg N kg^-1and was higher than C. The β-glucosidase and protease activity had more than 2 times higher in GM than C by 3-4 weeks after transplantation, and phosphatase activity had more than 2 times higher in GM than C in the whole season. Leaf color in C was stable around 30, however, unstable and fluctuated in GM. From the above, it was assumed that GM application increased the activity of microorganisms, and enhances the metabolism of N and P in the soil, made it possible to supply N and P equivalent to C, and resulting the same yield of the conventional.