Sustainable options for reducing carbon inputs and improving the eco-efficiency of smallholder wheat-maize cropping systems in the Huanghuaihai Farming Region of China

The large inputs to the winter wheat-summer maize cropping systems (WMSs) in the Huanghuaihai Farming Region (HFR) of China have increased resource consumption and pollution risk. The purposes of the current study were to seek effective ways to reduce the negative impacts of smallholder systems on the environment by using the life cycle assessment (LCA) method and data from field investigations and high-yield demonstration fields with WMSs in four representative counties across the HFR. High-yield demonstration fields with optimized fertilizer management had a higher carbon balance (CB), lower carbon intensity and higher fertilizer use efficiency than smallholder fields. The CB and carbon emissions differed among counties due to differences in input and output levels. Fertilizer application contributed the most to carbon emissions from WMSs in the HFR, accounting for 34.5% of the total carbon emissions. Thus, an efficient way to reduce the carbon footprint is to reduce the difference in nitrogen application between farmers' and high-yield fields. The dominant WMS production unit in the HFR is smallholding, which requires large resource inputs and high carbon consumption for high yield. Therefore, optimizing the carbon input management of farmers' fields, especially the management of fertilizers, is crucial for promoting high-yield, low-carbon production and improving ecological benefits for WMS smallholders in the HFR, which will further promote clean and sustainable agricultural production in this region. (C) 2019 Elsevier Ltd. All rights reserved.