Energy budgeting for designing sustainable and environmentally clean/safer cropping systems for rainfed rice fallow lands in India

Efficient utilization of rice (Oryza sativa L.) fallow (∼11.6 million hectares) systems can accelerate the growth of Indian agriculture. But, bringing more area under cultivation is an energy-demanding process and a source of gaseous emissions in the era of climate change. Hence, development of environmentally sustainable cropping systems require for efficient use of rice-fallow lands for sustainable productivity. Therefore, the present study was conducted with the objective to identify sustainable and environmentally safer cropping systems with low global worming potential (GWP) and low energy requirement for rice fallow land of India. Seven diverse crops (e.g., toria (Brassica campestris var. toria), lentil (Lens culinaris), field pea (Pisum arvense), garden pea (Pisum sativum L.), green gram (Vigna radiata), black gram (Vigna mungo) and maize (Zea mays)) were introduced in rice-fallow system by adopting no-till (NT) production technology to develop sustainable and environmentally cleaner production systems in a subtropical climate of Tripura, India. All these rice-based cropping systems were evaluated on the basis of the energy requirements and system productivity. Results indicated that rice had the highest energy input followed by that for maize and the least for lentil. System productivity regarding equivalent rice yield was the highest in rice–garden pea system. The relative amount of energy input in all cropping systems involved 44–54% for chemical fertilizers, 13–17% for land preparation, 12–15% for diesel and 11–14% for labor. Total energy input of 28,656 MJ per hectare (MJ/ha) was the highest for rice–maize and the lowest of 22,486 MJ/ha for rice–lentil systems. The highest system productivity and the highest energy productivity were obtained for the rice–garden pea system. The GWP was lower for legume-based than that for cereal and oilseed-based cropping systems. The lowest GWP of 7.97 Mg CO2e/ha per yr was observed for the rice-lentil cropping system and the highest GWP of 8.39 Mg CO2e/ha per yr for the rice-maize cropping system. The rice-vegetable pea and rice-lentil cropping systems also had low greenhouse gas emission intensity. The rice–pea and rice–lentil cropping systems are recommended for the region because of their low energy requirement, high energy and system productivity and low GWP. These systems are suited for the efficient utilization of rice fallow lands of eastern India to sustain productivity while adapting and mitigating the climate change. © 2017 Elsevier Ltd