Energy efficiency and economics of rice cultivation systems under subtropical Eastern Himalaya

In the northeastern region (NER) of India (eastern Himalayas), rice (Oryza sativa) is grown in ~ 70% of cultivated land. Therefore, the identification of energy-efficient rice cultivation system is important to food security and sustainable intensification (SI). Thus, six rice cultivation systems, composed of conventional direct seeded (CT-DSR), conventional transplanted (TRP), no-till (NT) DSR, NT-TRP, system of rice intensification (SRI), and mechanized TRP, were evaluated for their energy and cost efficiency. Results showed that land preparation, application of chemical fertilizers, farm yard manure, and seeding and/or transplanting operations consumed > 80% of energy input in all rice cultivation systems. Energy input was the highest in mechanized TRP (15371 MJ ha-1) and the lowest in NT-DSR (9162 MJ ha-1). Average grain yield obtained was the highest under SRI (4.72 Mg ha− 1), followed by CT-TRP (4.34 Mg ha− 1), mechanized TRP (4.23 Mg ha− 1), and NT-TRP (3.52 Mg ha− 1). Grain and biomass output energy was the highest in SRI system (148811 MJ ha-1), followed by that for the conventional TRP and mechanized TRP. The NT-DSR system was the most energy-efficient rice cultivation practice (output-input ratio: 11.00), whereas mechanized TRP was the least energy efficient (output-input ratio: 8.6). The lowest energy input (2900 MJ Mg-1) per unit of grain yield was recorded for the SRI system. Both the input-cost and the benefit-cost ratio in mechanized TRP were lower than that under SRI.