-
Summary of our research
A research group led by Professor Nobuhito Sekiya and Professor Kunio Watanabe from the Graduate School of Bioresources, Mie University, Associate Professor Shunsuke Ichikawa from the Graduate School of Education, Mie University, and Lecturer Mchuno Alfred Peter from the College of Agriculture and Food Engineering, University of Dar es Salaam, discovered that variations in soil microbial communities created by topography significantly contribute to organic rice productivity. The research group conducted soil microbial analysis, soil incubation experiments, and on-farm trials in the valley bottom and hillslope of Kaya Valley in Yosano Town, Kyoto Prefecture. The results revealed that valley bottom fields had lower proportions of genes involved in microbial denitrification and ammonia utilization compared to hillslopes, indicating more efficient utilization of nitrogen from organic fertilizers by rice plants. On-farm trials confirmed that valley bottom fields supplied nitrogen to rice more efficiently than hillslopes, ultimately improving brown rice yield. This is the first study to demonstrate the necessity of considering topography-induced soil microbial communities when producing organic rice.
These findings were published online in the international academic journal Scientific Reports on July 10, 2025.
https://doi.org/10.1038/s41598-025-09111-x
Researcher information
SEKIYA Nobuhito
Graduate School of Bioresources Professor
Specialized area：
Crop Science
Current research field：
Sustainable Rice Production (Organic Rice Farming)
WATANABE Kunio
Graduate School of Bioresources Professor
Specialized area：
Soil Physics and Hydrology
Current research field：
Fate of nitrogen and carbon in agricultural fields
Utilization of frozen soil and ground freezing
Water, heat and solute transport in soil during freeze-thaw processes
ICHIKAWA Shunsuke
Faculty of Education Associate Professor
Specialized area：
Biochemistry, Applied Microbiology
Current research field：
Elucidation of the crucial functions collaboratively performed by diverse microorganisms in soil, the gut, fermented foods, and other environments.