Energy auditing and optimization approach for improving energy efficiency of rice cultivation in south-western Punjab, India

Highlights: • Energy input was 52.4 GJ ha⁻¹ and energy output was 259 GJ ha⁻¹ in rice cultivation. • Irrigation and fertilizers had highest contribution (64.7%) in total energy input. • Data envelopment analysis was used to optimize input energy use in rice cultivation. • Saving of 8.8% of total energy input is possible with current yield level. -- Abstract: Rice (Oryza sativa L.) is an important energy intensive cereal crop in India. In the present study, energy input and output were audited to optimize energy use in rice cultivation using data collected from 40 farmers during face-to-face interview. Average total energy input (E_I) of 52.4 ± 1.3 GJ ha⁻¹ produced total energy output (E_O) of 259 ± 4.7 GJ ha⁻¹, with energy productivity (E_P) of 0.16 kg MJ⁻¹. Results revealed that rice cultivation was energy efficient with energy ratio (E_R) of 5.0 ± 0.12 and net energy gain (NEG) of 206 ± 4.5 GJ ha⁻¹. In rice, irrigation water (∼40%) and chemical fertilizers (24.7%) had highest contribution towards E_I. A non-parametric production function of DEA (Data Envelopment Analysis) applied to optimize energy use in rice, elucidated 20 decision making units (DMUs) as efficient, whilst 50% as inefficient. The average technical efficiency (TE), pure technical efficiency (PTE) and scale efficiency (SE) of rice farms were 0.94, 0.97 and 0.97, respectively. Our results revealed that between 9.4 and 2170 MJ ha⁻¹ energy (0.2 and 46.9% of total saving) could be saved, if inefficient DMUs adopt the management practices of efficient DMUs. An average energy saving of 579 ± 166 MJ ha⁻¹ by efficient DMUs accounts for ∼8.8% of the E_I.