| Based on the emergy analysis, characteristics of the emergy flow, the input and output of emergy, and emergy index were investigated in the “pig-methane-grain” circular agriculture, straw returning and single breeding. Horizontal comparison analysis showed that, the ESR of the mode of “pig-methane-grain” was increased by 0.5% compared with the single pig raising system, while the EYR was increased by 10.84 and 5.43, respectively. The EISD was increased by 5.81 and 5.03, respectively. The ELR was decreased by 10.76 and 0.97, respectively. The EWR was 8.63% less than that by the single pig raising. This was found to be the best production mode with optimal ecological economic benefit, low emission, small environment pressure and sustainable development. This mode was also found to be suitable for general extension in Guanzhong Plain and its vicinities. To promote economy development and advance the popularization of “pig-methane-grain” mode, modern technologies should be employed as well. |