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Sweet potato (Ipomoea batatas L.) is a promising food and industrial crop that plays an important role in China's agricultural poverty relief strategy. Selecting an appropriate cropping system for sweet-potato production could simultaneously achieve energy, economic, and environmental benefits. Therefore, the comprehensive assessment of diversified sweet-potato-based cropping systems (i.e., sweet potato monoculture (SP), continuous sweet potato cropping (SPSP), sweet potato–rice (SPRI), sweet potato–maize (SPMA), and sweet potato–potato (SPPO)) in South China was conducted with a field survey and life-cycle assessment. The data were collected quantitatively using a questionnaire for face-to-face interviewing of 70 farmers. The results indicated that the annual crop yield (sweet potato equivalent yield) of five cropping systems was in increasing order as SPPO > SPSP > SPMA > SPRI > SP. The SPMA system exhibited the highest net energy (499.09 GJ/ha) and energy rate (7.77). The SPSP system performed better in energy efficiency (0.90 kg/MJ), net return (140,284 CNY/ha), benefit to cost rate (3.20), and eco-efficiency (45 CNY/kg CO2-eq). The annual greenhouse-gas (GHG) emissions of five cropping systems ranked from lowest to highest as follows: SP < SPRI < SPSP < SPMA < SPPO. With comprehensive consideration, extended rotation systems (e.g., SPMA, SPRI, and SPSP) are proposed because they could effectively reduce GHG emissions while maintaining or even increasing the system's productivity (ensuring food safety) in South China. [ABSTRACT FROM AUTHOR]

Sweet potato (Ipomoea batatas L.) is an important starch-producing crop used worldwide. However, few studies have been conducted on the energy efficient, cost benefit, and greenhouse gas (GHG) emissions of sweet potato production. To address this issue, the data were collected using a questionnaire for face-to-face interviews of 78 sweet potato growers and 74 reference crop (i.e., rice, maize, and potato) growers in Guangdong province. Results revealed that sweet potato production exhibited the highest value of energy efficiency (0.83 kg MJ−1) and economic productivity (0.85 kg CNY−1) among four crops. The GHG emissions from sweet potato production (1165 kg CO2-eq ha−1) were significantly higher than GHG from rice and maize but lower than GHG from potatoes. Moreover, plantation size significantly (p < 0.05) affected inputs of labor, machinery, and diesel fuel and further affected the energy rate, energy efficiency, and GHG emissions of sweet potato production. Sweet potato production in small-size farms (<2.0 ha) exhibited the highest energy efficiency (0.97 kg MJ−1) and the lowest GHG emissions (1045 kg CO2-eq ha−1). Quartering assessments based on energy efficiency, economic productivity, and GHG emissions showed that fertilizers and labor were the major contributors to energy consumption, economic costs, and GHG emissions. Future efforts should be made to reduce fertilizer application and increase fertilizer use efficiency for sustainable sweet potato production. [ABSTRACT FROM AUTHOR]