Emergy Study on Dike-Pond Eco-agricultural Engineering Modes

Three different dike pond eco agricultural engineering modes are studied with emergy analysis method combined with the latest emergy index for sustainable development (EISD) through system level and subsystem level in south China. The dike pond systems are separated into planting subsystem, pig breeding subsystem and fishery subsystem. The result is that mode Ⅲ(melon melon cabbage pig six domestic fishes combined with Siniperca chuatsi B.) is the best one on sustainable development. The EISD of mode Ⅲ (3.62) is 0.583 times higher than that of modeⅠ(melon melon cabbage six domestic fishes) and 0.297 times higher than that of mode Ⅱ(melon melon cabbage pig six domestic fishes). With higher economic benefits but much higher environmental impact, the sustainable development potential of planting subsystem is the lowest. Although the economic benefit of pig breeding subsysten is not higher, its indirect benefit is good. With higher economic benefit and lower environmental impact, the sustainable development potential of fishery subsystem is the best among the three subsystems. The result shows that perfect agricultural engineering modes should try to meet the social economic need and to realize local roundup characteristics at the same time.