Dry direct-seeded rice in north-eastern Japan: management and future prospects

Continuing decreases in the agricultural workforce in Japan necessitate labour-saving rice production systems. One system is dry direct seeding of rice, as recently implemented in north-eastern Japan. Many studies are reported only in Japanese. Here we introduce them to readers in other countries facing similar social problems. Yields of dry-seeded rice are ~10% lower than those of transplanted rice. Weed control, land preparation, and spatial variability of soil are important to field management. A cool climate and low N use efficiency constrain rice growth. Both plant N uptake per amount applied and yield per unit N uptake are lower in dry direct-seeded rice. Enhancing source capacity during grain filling is a key to increasing yield. Climate change, energy use, and N pollution constrain sustainable production. Direct-seeding cultivation can reduce the energy inputs per yield and per area relative to transplanting. Improving fertilizer use efficiency will reduce fossil fuel use. Over the past 30 years, rice yield per unit area in Japan has not changed, whereas yield per working hours has increased. Considering yield per working hours could further improve rice production in Japan.