Characteristics of energy-nutrient flow of multiple cropping rotation systems in paddy field

Multiple cropping rotation system has been an important measure for development of recycling agriculture management. Energy conversion and material recycling have constituted the basic functions of ecosystems and the most important researches on farmland ecosystems. In order to investigate the advantages of multiple cropping rotation farming systems, a field experiment was carried out to analyze the characteristics of energy conversion and material recycling in continuous cropping and crop rotation systems in paddy ecosystems in Nanchang, Jiangxi Province. The results showed that multiple cropping rotation system improved energy conversion and material recycling in paddy ecosystems. In terms of energy conversion, average gross primary productivity, total energy investment, solar energy utilization and auxiliary energy output-input ratio of multiple cropping rotation treatments were respectively 31.35%, 4.90%, 31.36% and 25.04% higher than those of continuous cropping system. In terms of material recycling, K nutrient utilization was significantly higher than continuous cropping. N and P output/input of every treatment was less than 1, showing that N and P maintained a positive balance in paddy ecosystems. However, the smaller K input than output in paddy systems showed serious loss of K in the system. Thus multiple cropping rotation system improved energy conversion and material recycling in rice cultivation regions in South China. Multiple cropping rotation system not only induced a state of virtuous cycle in farmland ecosystems, also promoted the development of circular agriculture.