Energy efficiency of Populus deltoides G(3) Marsh agroforestry of a 3-year-old system with intercropping of maize-wheat in crop I and pigeonpea in crop 11 and of a 9-year-old system with turmeric, a shade loving crop was studied at Pusa, Bihar in eastern India. Energy fixation, storage, net allocation in agronomic yield and energy released and exit from the 9-year-old system was 1.53, 4.30, 0.43 and 3.37 times in crop I and 1.67, 4.60, 0.53 and 3.30 times in crop 11 of the 3-year-old agroforestry system. The energy conservation efficiency in the 9-year-old system was higher (1.91%) as compared to crop 1 (1.24%) and crop 11 (1.15%) of the 3-year-old agroforestry system. The energy accumulation ratio in the 9-year-old system was 2.82 and 2.77 times higher in crop I and crop 11, respectively, of the 3-year-old agroforestry system. The 3-year-old agroforestry system showed lower energy accumulation ratio resulting from less energy accumulation in perennial turnover in the from of leaf of tree and agricultural crops. The crop 11 system of the 3-year-old poplar agroforestry was more efficient system of management due to higher quanta of energy and higher cash return but one has to opt for shade loving intercrop turmeric with increase in age of the poplar plantation and more canopy closure. (c) 2005 Elsevier Ltd. All rights reserved.