Conservation tillage practices, including no-tillage, stubble retention, and crop rotation, represents transformative strategies to enhance productivity, soil health, and long-term sustainability. However, quantifying their energy efficiency and environmental impacts of small-scale forage-crop rotation systems has not well explored, primarily due to intensive farming practices and labor requirements. To address this gap, a sustainability evaluation index (SEI) was developed to systematically assess the multidimensional performance of 22years of conservation tillage practices, focusing on SOC sequestration, energy utilization, net benefits and carbon footprint (CF). Four tillage management practices were evaluated in a forage-crop rotation system, including conventional tillage (T), conventional tillage + stubble retention (TS), no-tillage (NT) and no-tillage + stubble retention (NTS) that the results showed that the implementation of T, TS, NT and NTS treatments for a period of 22 years increased SOC storage by 36.1 %, 53.1 %, 35.5 % and 64.5 % in the 0-30 cm soil layer, respectively. Notillage decreased indirect greenhouse gas (IGHG) emissions from agricultural practices, while stubble retention improved net GHG mitigation through enhanced SOC sequestration. The NTS treatment enhanced energy use efficiency by 63.0 %, compared with T, resulting in net benefit of 717 $ ha-1 yr-1. Additionally, NTS reduced CF by 22.3 %-41.1 % and increased SEI by 53.5 %. The T treatment increased SOC storage, thereby challenging the prevailing assumptions regarding its long-term effects in smallholder systems. Overall, the NTS treatment demonstrated sustainable gains, underscoring its essential role in smallholder agroecosystems. This study redefines the paradigm of conservation tillage, highlighting the trade-offs and synergies among energy, economics, and GHG emissions.