Northeast China serves as a crucial grain production base in the country and plays a vital role in national food security. However, the excessive input in grain production processes significantly affects agricultural carbon emissions in this region. Promptly elucidating the disparities in carbon emissions from agricultural inputs across different production processes is therefore imperative for advancing efficient low-carbon agriculture in Northeast China.

Based on a series of statistical data such as agricultural input, output and sown area of major crops in Northeast China from 1991 to 2020, this study took the entire production cycle of crops as the research boundary, and uses methods, such as carbon emission coefficient method, geographical detector, spatial autocorrelation test and standard deviation ellipse analysis, to analyze the temporal variation law and spatial distribution characteristics of carbon emissions from grain production input, and finally made relevant countermeasure analysis.

(1) In the past 30 years, the carbon emissions from agricultural input in Northeast China have shown an overall increasing trend, with a spatial distribution characteristic of being high in the middle (Shenyang-Changchun-Harbin line) and low in the surrounding areas, with an average annual carbon emission of 38.2 million tons. In 2020, the carbon emissions from agricultural input in various provinces in Northeast China in descending order were: Heilongjiang Province (19.5 million tons), Jilin Province (10.91 million tons), Liaoning Province (10.11 million tons), and Eastern Inner Mongolia (9.19 million tons). (2) Both the carbon emissions from agricultural input per sown area (Ga) and the carbon emissions from agricultural input per output (Gy) in Northeast China showed a distribution characteristic of being high in the east (eastern Liaoning Province, eastern Jilin Province) and low in the west (Eastern Inner Mongolia, western Heilongjiang Province). Ga increased from 1.37 kg CO₂eq·hm^-2 in 1991 to 1.67 kg COeq·hm^-2 in 2020, an increase of 21.9%, while Gy decreased from 0.36 t CO₂eq·t^-1 in 1991 to 0.32 t CO₂eq·t^-1 in 2020, a decrease of 11.1%. (3) The center of gravity of carbon emissions from agricultural input of crops in Northeast China showed an overall migration trend to the northwest of Changchun.

It was concluded that in the past 30 years, the carbon emissions from agricultural input in Northeast China have shown an upward trend, but the overall migration was to the northwest; the Ga of agricultural input of crops has continued to increase over time, while Gy has continued to decrease, but both showed a spatial distribution characteristic of being high in the east and low in the west. In the future, it was necessary to further strengthen the intelligent network management and control of agricultural input, improve the energy utilization efficiency of agricultural machinery, promote intelligent agricultural machinery, and innovate differentiated farming systems in various provinces and cities, so as to promote the carbon peak and carbon neutrality in the agricultural field.