Analysis On Ecology Benefit In Double Paddy Field Of Multiple Cropping Based On Emergy Theory In Southern Hilly Areas Of China

Based on emergy theory and ecological methodology, this paper take double paddy field of multiple cropping as research object study has studied the emergy input-output in different kinds of cropping pattern of nine in Southern Hilly Areas of China, and then evaluate it with correlative index of emergy theory, such as emergy investment ratio, net emergy yield ratio, environmental loading ratio, emergy sustainable index and so on, for picking out the best of cropping pattern.This study showed that:1. Broad beans-early rice-late rice and peas-early rice-late rice cropping patterns in net emergy yield ratio and emergy sustainable index are better than other cropping patterns. They can use emergy better than other cropping patterns during the process of growth of broad beans peas-early and double paddy, that is to say they have quick effects of investment, high economic benefits and well sustainable of emergy.2. Green manure-sugar cane+soybean cropping pattern have a high economic benefits and product competitiveness, but it asks for a highly-qualified level of management. Green manure-spring corn intercropping soybean-late rice ask for a high investment of purchasing emergy, but it is inferior to other cropping patterns in net emergy yield ratio, environmental loading ratio and emergy sustainable index and so on.3. Winter fallow-early rice-late rice, green manure-early rice-late rice and mixed green manure-early rice-late rice cropping patterns have high self-sufficient ability and anti-jamming ability, but they are inferior to other cropping patterns in net emergy yield ratio and emergy sustainable index, which means that their product competitiveness and economic benefits are bad.4. Cropping rape-early rice-late rice cropping pattern has a environmental loading ratio and ask for a high investment of purchasing emergy, but it has a high net emergy yield ratio, and this cropping pattern is in favour of the growth of double paddy. Barley-early rice-late rice cropping pattern has a high environmental loading ratio and lower net emergy yield ratio.