Energy analysis and economic assessment of a rice-turtle-fish co-culture system

Rice-fish system is the first globally important agricultural heritage system (GIAHS) and could be a potential option to improve modern rice production. This paper investigates energy flows and economic profits of two rice production agroecosystems in China. Results suggest that total energy input in rice-turtle-fish co-culture (RTF) was 18,889.63 MJ ha(-1), less than that of rice monoculture (RM) (20,289.44 MJ ha(-1)). Total energy output in RTF was 82,836.57 MJ ha(-1), higher than that of RM (77,221.21 MJ ha(-1)). The product safety index (PSI) in RTF and RM were -0.23 and -0.77, respectively, which indicated the products safety potential in RTF was higher than that of RM. The energy sustainable development index (ESI) in RTF and RM were 9.03 and 0.66, respectively, which illustrated RTF has abundant developmental potential, while RM is more of a consuming-type ecosystem. The output/input, gross profits, and net profits in RTF were 5.17, 99,531.30 CNY, and 98,729.96 CNY, respectively, all higher than that of RM (4.58, 11,335.67 CNY and 11,034.33 CNY, respectively). Consequently, RTF has greater potential to reduce agro-chemicals, improve energy use efficiency, and increase economic profits compared to RM.