Economic benefits and carbon footprint of a spring mung bean-summer maize cropping system in the North China Plain

The North China Plain is an area of major grain production in China. The intensive winter wheat-summer maize cropping system has led to increasingly excessive nitrogen fertilization, over-exploitation of groundwater, and increased carbon emissions. Therefore, adjusting the existed planting structure and constructing a resource-saving planting system is critical to alleviate the ecological problems of the region. Here, the yield, economic benefits, carbon emissions, and carbon footprint were evaluated between spring mung bean-summer maize (MM) and winter wheat-summer maize (WM) cropping systems based on a field experiment and life cycle assessment (LCA). The yields of mung bean and maize were 1 760.1 kg·hm^-2 and 8 775.8 kg·hm^-2 under the MM treatment, respectively. The annual economic equivalent yield and annual net income of the MM treatment were 18 833.4 kg·hm^-2 and 27 085 ￥·hm^-2, respectively, which were 20.4% lower (P < 0.05) and 20.2% higher than those under the WM treatment, respectively. The annual carbon emission from the MM treatment was 4 642.1 kg(CO₂-eq)·hm^-2, which was 36.1% lower than that from the WM. Additionally, the carbon footprint per unit of economic benefit of the MM treatment was 0.17 kg(CO₂-eq)·￥^-1, 48.5% lower (P < 0.01) than that of WM. Therefore, the introduction of MM systems to replace some WM systems could potentially increase the net income of farmers, as well as reduce carbon emissions and carbon footprint.