Human interventions, such as farmland management, have long been considered crucial for soil carbon sequestration, but little is known about the exact impact of these interventions on the net carbon flux, represented by net ecosystem productivity (NEP). Here, using multiple long-term, large-scale data and statistical data, we reveal that 75.54% of farmland NEP in China experiences an increase, with northern regions showing the greatest potential for future farmland carbon sequestration. This growth is primarily attributed to the role of farmland management, especially the enhancement of no-tillage, land consolidation and multiple cropping level (17.02%, major grain-producing areas in 2020). Notably, the current unreasonable practices of mechanized straw returning and irrigation have a negative impact on farmland NEP. Our results show that it is imperative to acknowledge the crucial role of human interventions on farmland NEP to strike a balance between food security and farmland carbon sequestration.

A change in agricultural land management scale leads to the recombination and adjustment of production factors, which have an important impact on agricultural carbon emissions. There are few studies on the connection between the scale of land management and agricultural carbon emissions. In this study, we empirically examined the relationship between planting scale and agricultural carbon emissions using the threshold model, which allows the data to endogenously generate several regimes identified by the thresholds. The results showed that from 2003 to 2018, carbon emissions from planting first increased and then decreased, reaching their highest in 2015. Across the whole country in the main rice- and wheat-producing regions, the scale of planting land has a threshold effect on agricultural carbon emissions, showing an inverted “U” shape. Carbon sinks and natural disasters significantly affected planting carbon emissions in the above three regions. The amount of fiscal support for agriculture significantly affects planting carbon emissions in the national and main wheat-producing regions, while peasants’ per capita income significantly affects planting carbon emissions in the main rice- and wheat-producing regions. This study provides policy makers with new ideas, in that continuously expanding the scale of agricultural land management is conducive to reducing agricultural carbon emissions.