“奶牛-沼气-牧草”循环型农业系统的能值分析

为探讨“奶牛-沼气-牧草”循环型农业模式（模式I）的结构功能和生态经济效益，应用能值分析方法对其进行研究，并与单一奶牛养殖模式（模式Ⅱ）进行比较。结果表明：模式Ⅰ的净能值产出率（4．06）比模式Ⅱ（4．13）低；模式Ⅰ能值可持续发展指标值为10．27，模式Ⅱ为9．57，模式Ⅰ具有更高的可持续发展能力；模式Ⅰ的环境负载率（0．11）低于模式Ⅱ（0．12），并且模式Ⅱ能值废弃率为21．72％，模式I为0，因此模式Ⅰ对环境的压力小；模式Ⅰ产出能值反馈率达到30．63％，系统自组织能力强。模式Ⅰ的净效益是模式Ⅱ的1．13倍，但产投比是模式Ⅱ的97．64％。以能值-货币价值计算的生态经济效益分析结果与实际经济效益分析结果基本一致。因此，模式Ⅰ具有环境压力小、自组织能力强、可持续发展能力较强的特征，但仍需进一步优化系统内部结构，提高生产效率。

Emergy Analysis of Circular Agriculture Mode of ＂Dairy Cattle-Biogas-Forage ＂

To study and compare the circular agriculture system of ＂dairy cattle-biogas-forage＂ （Mode Ⅰ ） with the conventional dairy farm system （ Mode Ⅱ ） in ecological and economic benefit, emergy analysis method is used. Results show that the net energy yield ratio in Mode Ⅰ was 4.06, lower than that （4. 13） in Mode Ⅱ. The emergy sustainable development index was 10. 27 in Mode Ⅰ and 9.57 in Mode Ⅱ, suggesting Mode Ⅰ is more capable of sustaining development than Mode Ⅱ. The environmental loading ratio of Mode Ⅰ was 0. 11, lower than that （0. 12） of Mode Ⅱ , and the emergy waste ratio was 21.72% in Mode Ⅱ but 0 in Mode Ⅰ, suggesting that Mode Ⅰ creates less pressure on the environment than Mode Ⅱ does. The feedback ratio of yielded emergy was 30.63% in Mode Ⅰ but 0 in Mode Ⅱ , suggesting that Mode Ⅰ is higher in self-organizing ability. The net income of Mode Ⅰ was 1.13 times that of Mode Ⅱ , but the output-input ratio of Mode Ⅰ was 97.64% of Mode Ⅱ. Analysis of the eco-economic benefit of Mode Ⅰ based on the emergy-monetary value showed it was close to the actual economic benefit. Therefore, Mode Ⅰ can be characterized by less environmental pressure, higher self-organizing ability and high sustainable development capability, but it still needs to further optimize its system internal structure and improve its productivity.