Abstract: Investigating the size and composition of carbon footprint is a key issue for the low carbon development of rice-Procambarus clarkii integrated farming system (R-P) in China. In this study, a field investigation was conducted to analyze the composition of the carbon footprint of R-P with carbon footprint theory and its major influencing factors. The results show that the carbon footprint per area of R-P was 7 859 kg·hm^-2, which was between that of rice-wheat farming system(R-W, 10 650 kg·hm^-2) and single rice farming system(SR, 5 483 kg·hm^-2). The carbon footprint per unit output value and carbon footprint per unit profit of R-P are 0.11 and 0.26 kg·Yuan^-1, which are 64.26% and 60.65% lower than that of rice-wheat farming system and 67.37% and 45.02% lower than that of single rice farming system, respectively. R-P significantly decreased direct carbon emissions, but did not affect indirect carbon emissions, compared with rice-wheat farming system. And R-P significantly increased indirect carbon emissions, but did not affect direct carbon emissions, compared with the single rice farming system. The carbon footprint of R-P showed a "parabola" trend with Procambarus clarkii yield, output value and profit. When the carbon footprint reached to 7 458, 7 855, and 7 363 kg·hm^-2, the yield, output value and profit of R-P can be maximized, respectively. The scale of R-P farm has a significant impact on the carbon footprint of R-P. The small-scale (< 5.00 hm²) and large-scale (> 20.00 hm²) farm is conducive to reducing the carbon footprint and increasing output value and profits. Overall, R-P can effectively reduce emissions and increase efficiency, compared with the traditional farming systems. However, we should pay attention to the trade-off between carbon footprint and economic benefits in order to promote the green and efficient development of R-P.

Key words: Procambarus clarkii, integrated farming system, carbon footprint, production scale, greenhouse gases