Sustainable Rice Cultivation: Energy Analysis of Direct-Seeded Rice and Mechanical Transplanting Techniques

Rice cultivation under conventional puddled transplanted systems is highly energy- and resource-intensive, leading to excessive water use, rising production costs, and increased greenhouse gas emissions. This study aims to analyze and compare the energy expenditure, carbon footprint, yield-related energy indices, and operational costs of different rice cultivation system in order to identify the most energy-efficient and sustainable rice cultivation system for Punjab, India. Four rice establishment techniques, namely, direct-seeded rice (T1), manual transplanting (T2), mechanical transplanting using a ride-on transplanter (T3), and mechanical transplanting using a walk-behind transplanter (T4) were evaluated. Energy inputs were classified into direct (human labour, diesel, electricity) and indirect (seed, fertilizer, chemicals, machinery) sources, while greenhouse gas emissions were estimated using standard CO₂-equivalent emission co-efficient. Results showed that manual transplanting (T2) was the most energy-intensive system, recording the highest total energy input (57,280.76 MJ ha^-1), which was 11.6% higher than direct-seeded rice (T1). It also exhibited the maximum specific energy (8.48 MJ kg^-1) and the greatest carbon footprint (4564.04 kg CO₂-eq ha^-1), with emissions 21.25% higher than DSR, mainly due to intensive irrigation, higher electricity consumption, and greater labour use. In contrast, direct-seeded rice (T1) required the lowest total energy input (51,334.25 MJ ha^-1) and minimum direct cultivation cost (₹36187 ha^-1). It also recorded the lowest total CO₂ emissions (3764.31 kg CO₂-eq ha^-1), reflecting its reduced groundwater pumping requirement. Mechanical transplanting with a ride-on transplanter (T3) produced the highest grain yield (8225 kg ha^-1), which was 22.8% higher than DSR (T1). The treatment T3 also achieved superior energy use efficiency (2.15) and energy productivity (0.15 kg MJ^-1). However, total energy input of treatment T3 remained 7.0% higher than DSR, and its CO₂ emissions were 17.4% higher than T1 treatment. Overall, the study concluded that direct-seeded rice (T1) is the most energy-efficient and sustainable rice establishment method, offering substantial reductions in energy consumption and CO₂ emissions while maintaining acceptable productivity and lower production costs. Mechanical transplanting provides productivity advantages, whereas manual transplanting remains the most energyintensive and environmentally burdensome option.