Are we ready to cultivate sweet sorghum as a bioenergy feedstock? A review on field management practices

This review discusses the potential production for energy purposes of sweet sorghum (Sorghum bicolor L.), a C ₄ crop native to tropical areas with juicy stalks rich in sugars from which ethanol could be produced at lower costs than from starchy crops like maize. The growing interest in bioenergy and particularly in bioethanol is a great challenge for this relatively new crop that could be used for both thermo-electrical energy and biofuel. Nonetheless, the quantitative and qualitative production of sweet sorghum strongly depends on the use of appropriate and improved agronomic management techniques which is, in some aspects, still largely unknown. This review attempts to gather the sparse information on best agricultural practices for sweet sorghum, still very much a wild species in many aspects, while identifying the weak points that need to be deepened in further researches, especially under temperate climates. Sweet sorghum is a row crop and therefore the agronomic management and other well known cultural methods used for conventional row crops such as maize can be adapted. In general, low input requirements, low production costs, drought resistance, versatility, and high yields gives to sweet sorghum a better energy balance compared to other competing energy crops, especially if bagasse is also processed to energy. In non-traditional potential growing areas (such as in temperate climates of Europe) where productivity/adaptation improvements through genetically modified crops is not allowed, appropriate and sustainable agricultural practices constitute the most immediate option to improve yields. Based on scientific reports, research efforts seem particularly needed for harvesting techniques, and handling and storing.