Conservation Agriculture offers system optimization for legume intensification: An on-farm study of western Indo-Gangetic Plains

The crop production in Indo-Gangetic Plain (IGP) facing serious challenges of decaling factor productivity under changing climatic scenarios with shrinking water resources driving future food insecurity. To develop sustainable intensification model for future sustainability in the food basket of India’s IGP by identifying of suitable options for legume integration through system optimization practices (SOP) in rice-wheat and diversified cropping systems having higher productivity, profitability and environmental security. The field experiments were conducted at the four locations of the farmer’s field in Karnal, Haryana, India. We evaluated SOP of mungbean under zero tillage (ZT) with residue recycling and improved management practices integrated in CTR-WMb (conventional till rice-ZT wheat-mungbean), DSR-WMb (direct seeded rice-ZT wheat-mungbean) and triple ZT (raised bed) based diversified SOP of MWMb (maize-wheat-mungbean), MMuMb (maize-mustard-mungbean) and SWMb (soybean-wheat-mungbean). The on-farm study revealed that the mungbean inclusion with diversified SOP had significantly lesser water use by 51 ha-mm with enhanced partial factor productivity of total nitrogen and phosphorus (NP) applied by 14–29 % over DSR-WMb. However, the global warming potential (GWP) reduced by 60 kg CO2 eql/ha with diversified SOP over CTR-WMb. Similarly, the non-renewable energy use was reduced by ∼1200 MJ/ha with significantly increased net energy output and non-renewable energy use efficiency (EUE) by 137–203 and 27–38 %, respectively with diversified SOP over DSR-WMb. Additionally, the mungbean grain yield increased by 13 % in CTR-WMb, while the grain yield increased by 15–30 % in diversified SOP over DSR-WMb. The net returns increased by 40 USD/ha in CTR-WMb, while it significantly increased by 80–164 USD/ha in diversified SOP over DSR-WMb. However, the significantly lowest yield attributes and yield, net returns, resources use efficiency (water, nutrients and non-renewable energy) and eco-efficiency were recorded with DSR-WMb. Therefore, the mungbean inclusion in DSR-WMb was not found to be a feasible option compared to CTR-WMb and thus later can be scaled up in the existing rice-wheat system. Moreover, the mungbean inclusion with diversified SOP (MWMb/MMuMb/SWM) under ZT and residue retention produces more food with efficient use of recourses (water, nutrients and energy) for more (population) to ensure nutritional food security and environmental sustainability in we