Designing energy-efficient, economically sustainable and environmentally safe cropping system for the rainfed maize-fallow land of the Eastern Himalayas.

Achieving a circular economic model in agriculture and meeting the food requirement of the growing population is a global challenge. The task is much more daunting in the Eastern Himalaya where low productive maize-fallow is a predominant production system. To enhance system productivity and energy use efficiency while maintaining environmental sustainability and economic profitability, therefore, energy-efficient, low carbon footprint (CF; CO2-e) and profitable short duration crops must be made an integral part of the maize fallow system. Thus, six cropping systems viz., maize-fallow, maize-French bean, maize-soybean, maize-black gram, maize-green gram, and maize-toria were evaluated for seven consecutive years (2011-2018) to assess their energy requirement and efficiency, carbon footprint (CF; CO2-e), economic returns and eco-efficiency. The results revealed that the maize-French bean system had the highest system productivity (11.4 Mg ha-1), energy productivity (17.9), energy profitability (15.9) and non-renewable energy use efficiency (9.97). The maize-French bean system had also the highest net profit (US$ 3764.5 ha-1) and benefit to cost ratio (2.54). The energy consumed under different inputs/activities across the cropping systems for chemical fertilizers, diesel and machinery ranged from 50.0-62.7%, 17.3-20.8% and 4.6-15.4%, respectively. The maize-fallow system had the highest CF (0.34 kg CO2 e per kg grain) while, the maize-French bean system had the lowest CF (0.19 kg CO2 e per kg grain). The maize-French bean system had also considerably increased eco-efficiency both in terms of energy use (US$ 0.23 MJ-1) and (US$ 1.78 per kg CO2 e) over maize-fallow system. Thus, the study has suggested that maize-French bean system is energy-efficient, economically viable and environmentally safer systems to utilize maize fallow and improve food security, may help in achieving green/circular economy.