Technological development and future prospects of dry direct seeding using plowing and compaction for paddy-field crop rotation systems incorporating maize in the Tohoku region, Japan

In the Tohoku region of Japan, a cold-climate area, paddy-field agriculture faces challenges due to the aging population, the decline in farming labor, and the prolonged decline in the price of rice. These factors have accelerated the adoption of labor-saving, low-cost cultivation methods, such as dry direct seeding of rice using plowing and compaction (DDSPC). DDSPC is a mechanized system that is well suited to large-scale fields and high-speed operations, and uses multipurpose farming machinery for rice and upland crops. In DDSPC, compaction primarily suppresses vertical water infiltration, thereby preventing water leakage and stabilizing crop establishment and input efficacy without forming a puddled plow sole. This makes DDSPC a promising method for rice cultivation and a core technology for developing paddy field crop rotation systems. A two-year, three-crop rotation involving rice, wheat, and soybean was first established, achieving yields comparable to conventional practices. The rotation system was subsequently expanded to include grain maize, overcoming its vulnerability to water damage through DDSPC without a plow sole. In converted paddy fields, compared to conventional rotary tillage, grain maize cultivation using plowing maintained yield while improving lodging resistance. Integrating grain maize further facilitated crop–livestock linkages through manure use to reduce chemical fertilizer inputs and feed utilization. This review synthesizes the development of DDSPC and its roles in paddy-field rotations in the Tohoku region, and discusses future directions for sustainable paddy agriculture under increasing labor constraints.