Integrated assessment of water footprint and energy production efficiency in different rice-rape rotation systems

Rice-rape rotation is one of the most important agricultural production systems in China. Studies were conducted to assess the water footprint (WF) and energy production efficiency (EPE) of six rice-rape rotation systems. Results showed that the annual equivalent yield in the wet directly seeded rice-rape rotation system was higher than that in the dry directly seeded rice-rape and transplanted rice-rape rotation system. However, the total energy input, and WF in the dry directly seeded rice-directly seeded rape (DDR-DR) rotation system were lower than those in other rice-rape rotation systems, while the energy production efficiency (EPE) was higher than that in other rice-rape rotation systems. The key to reducing the total energy input in the rice-rape rotation system is to reduce water and nitrogen inputs and tillage intensity during rice season and the nitrogen fertilizer rate in rape season. In summary, the wet directly seeded rice-directly seeded rape (WDR-DR) rotation system is suitable for promotion in rice-rape rotation production areas with good irrigation conditions and labor shortages, while the DDR-DR rotation might be the preferred planting mode for rice-rape rotation production areas with poor irrigation conditions and labor shortages.