Carbon Footprint Analysis of Wheat-maize Production System in Hebei Province

Analysis of carbon (C) footprint and related influence factors were beneficial for providing a theoretical support and scientific basis to low carbon agriculture development in Hebei province. Based on the statistical consumption of fertilizer, pesticide, agricultural film and diesel consumption, irrigation power consumption, sown area and yield of wheat and maize in Hebei Province in 2018, a life cycle assessment (LCA) method was used to calculate the C footprint during winter wheat and summer maize production process, which will provide a theoretical support and scientific basis for the development of low-carbon agriculture. The results show that the C emissions, C sequestration and C footprint of winter wheat were 952×10⁴, 463×10⁴ and 489×10⁴ t CO₂ eq in wheat season, and 899×10⁴, 588×10⁴ and 311×10⁴ t CO₂ eq in maize season, respectively. The annual total carbon emissions, carbon sequestration and carbon footprint of the province for the 2 crops were 1 851×10⁴, 1 051×10⁴ and 800×10⁴ t CO₂ eq, respectively. The C emissions and C footprint of winter wheat were 5.90% and 57.23% higher than that of summer maize, but the C sequestration was 21.26% lower than that of summer maize. The emissions related to irrigation, fertilizer and farmland dominated the CO₂ emission, which accounted for 37.00%, 31.17% and 18.69% of the total annual C emissions, respectively. The C sequestration of straw incorporation accounted for 84.78% of the annual C sequestration, which was significantly higher than C sequestration caused by chemical fertilizer application. C emissions contributed by chemical fertilizer and machinery were 49.54% and 43.97%, respectively, and the contribution to cost were both with nearly 40% of the total cost inputs, which are significantly higher than the contribution of other agricultural inputs to carbon emissions and cost. The positive C footprint indicate that wheat-maize production system is the source of carbon emissions. The large amount of irrigation water input and the higher nitrogen fertilizer application are the main reasons for the higher carbon emissions of winter wheat. Therefore, reducing the amount of fertilizer application and reducing water irrigation are the most direct and effective ways to the reducing of C emissions and production costs of winter wheat-summer maize production system in Hebei Province.