Integrated emergy and economic evaluation of tea production chains in Anxi, China

Emergy and economic methods were used to evaluate and compare tea production systems in Anxi, China. Tea production was classified into three phases, i.e., the nursery, the plantation and tea processing, and each phase was evaluated. The results showed that the nursery subsystems were profitable with an economic output/input ratio of 2.86. However, the inclusion of a nursery had no significant influence on the sustainability of the tea plantation system, because it was a small part of the total input to the system. Applying organic fertilizer to replace 66% of the chemical fertilizer decreased the pressure of chemical loading on the environment, and as a result the cultivation phase's emergy sustainability index (ESI) increased 2.10 times. However, due to the relatively high price of organic fertilizer and the labor to spread it, the economic output/input ratio (1.61) of the mixed organic and chemical fertilizer mode was less than that of the chemical fertilizer mode (1.80). If all the tea leaves used in the processing phase were produced on the farm, instead of purchased from outside, about 30% of the economic cost of processing could be saved, and as a result the economic output/input ratio would increase by 41%; the ESI would increase 5.48 times and the emergy index for sustainable development (EISD) would increase 11.05 times. The overuse of chemical fertilizer and low productivity of labor are key problems that need to be solved for further optimization of the Anxi tea plantation systems.