Temporal and spatial difference in carbon footprint of regional farmland ecosystem in Guangdong province

Taking Guangdong province as an exampled, estimates the temporal and spatial features of carbon absorption, emission and footprint of regional farmland ecosystem based on the statistics of fertilizer, pesticides, agricultural film usage, irrigation area, agricultural machinery power and crop output during 1992 to 2011. The results indicated that in the recent 20 years, the total amount of carbon absorption of crops showed a declining tendency, it is reduced by 27.17% from 40 170 200 ton in 1992 to 29 254 200 ton in 2011. The annual average reduction ratio was 1.66%. The total amount of carbon emission basically showed a gradual increasing tendency, it increased by 16.80% from 2 240 500 ton in 1992 to 2 616 900 ton in 2011. Carbon footprint of Guangdong farmland ecosystem showed a waving increase, it increased by 89.72% from 1992 to 2011. The annual average increase ratio was 3.43%. The ratio of carbon footprint and production land area of the corresponding period was gradually increased, In 2011 the ratio was 8.95%. There was carbon ecological surplus in Guangdong farmland ecosystem. The ratio of ecological surplus and production land area of the corresponding period was gradually decreased. Carbon footprint varied greatly among different parts of Guangdong.