Energy efficiency and water use indices for sweet potato (Ipomoea batatas L.) production under subtropical climatic conditions of Bangladesh

Abstract

To estimate energy use efficiency for sweet potato production in Bangladesh under subtropical climatic conditions, a study was conducted with 60 individuals (12 producers for each sweet potato variety) by using a structural questionnaire. The results revealed that the majority of the energy input was consumed by the pre-harvest activities (22,313.55 MJ ha−1 or 90.85%), of which fertilizer application (36.84%) and irrigation (35.24%) consumed the most energy input, with only 9.15% (2,248.42 MJ ha−1) consumed by the post-harvest activity for sweet potato production. The energy input involved in the production system was similar to the direct (12,149.76 MJ ha−1 or 49.47%) and indirect (12,412.21 MJ ha−1 or 50.53%) sources, while it was much higher in non-renewable sources (22,884.21 MJ ha−1 or 93.17%) with a minimum (1,677.76 MJ ha−1 or 6.83%) from renewable sources. The average energy use efficiency, energy productivity, specific energy, net energy, energy profitability and water-energy productivity of orange-fleshed sweet potato (OFSP) varieties 4.36, 1.22 kg MJ−1, 0.83 MJ kg−1, 82,511.73 MJ ha−1, 3.36 and 1.32 g m−3 MJ−1, respectively. The OFSP varieties showed better performance in respect of all the energy and water use indicators. HIGHLIGHTS Farmers generally grow crops in riverbank areas which need low irrigation; for example, sweet potato.; The estimation of energy and water use indicators are important for sweet potato, since this crop needs minimal water.; The study estimated energy and water use indicators for the production of sweet potato.; The orange-fleshed sweet potatoes showed better performance in respect of energy and water use indicators.;

Keywords

• energy input
• energy output
• sweet potato
• water indicators