A combination of intensive soil manipulation, low water and input efficiencies has resulted in declining soil and crop productivity, and a worsening soil organic carbon (SOC) stock and crop productivity in the eastern Himalayan agm-ecosystem. There is an urgent need to improve the carbon (c) stability with water-cum-energy efficient management for long-term sustainability. Experimental field was practiced under limited tillage with power tiller-based tilling for ten years (2001-2010). This experiment was designed for two years (2011 and 2012) with three tillage practices in the main-plots: i) conventional tillage (CT), ii) minimum tillage (MT), and iii) zero tillage (ZT), while in the sub-plots crop residues mulch (CRM): a) CRM at 4 Mg ha(-1) and b) no mulch (NM) was practiced under rainfed conditions. Results show that grain yield of maize improved by 16-31% in CT, whereas rapeseed yield improved by 26-28% with MT as compared to ZT during both the years. CRM improved the yield by 6-11% in maize and 20-25% in rapeseed over NM. Moreover, per plant biomass accumulation improved with CT+CRM by 42-44% in maize and MT+CRM by 10-24% in rapeseed during the both years. Likewise, CT maize and MT rapeseed along with CRM used water was recorded 378-467 and 200-201 mm. Moreover, similar trend was observed on water use efficiency (WUE) by 8.5-10.2 and 4.9-5.4 kg ha(-1) mm(-1), respectively. In terms of energy, CT and MT along with CRM were more energy exhaustive practices in both the crops; while in ZT recorded higher energy use efficiency (9.3 and 7.7) and productivity (0.7 and 0.4 kg MJ(-1)) in CT and MT, respectively. Adoption of ZT also increased bulk density (ph) by 3% over CT. The ZT along with CRM improved C stability by 6 folds than CT and 58% over NM. Considering all these facts, CT/MT along with CRM may be recommended to obtain higher yield, WUE, energy productivity and C stability in (Zea mays L.)- rapeseed (Brassica campestris L.) system in the eastern Himalayan agm-ecosystem.