Dynamics of carbon budget and meteorological factors of a typical maize ecosystem in Songnen Plain, China

Aim of study: Understanding the carbon budget and meteorological factor impacts of farmland ecosystems is helpful for scientific assessment of carbon budget and low-carbon agricultural production practices.Area of study: The Songnen Plain, NE China, in 2019.Material and methods<bold>:</bold> Based on eddy-related flux and soil heterotrophic respiration observations from a typical maize farmland ecosystem, using mathematical statistics and carbon balance equation methods, were analyzed.Main results: Soil respiration rate (R-s) and composition were influenced and controlled by the synergistic effect of surface soil temperature (T-s) and water content (W-cs). T-s played a leading role, while W-cs played an important role. T-s and W-cs had the greatest influence on the heterotrophic respiration rate (R-h), followed by R-s and autotrophic respiration rate (R-a). Daily variations of net ecosystem productivity were correlated with daily mean air temperature, latent heat flux, and sensible heat flux. Annual carbon revenue was 1139.67 g C m(-2), annual carbon expenditure was 456.14 g C m(-2), and annual carbon budget was -683.53 g C m(-2) in 2019. While considering that maize grain yield (-353.44 g C m(-2)) was moved out of the field at harvest, the net ecosystem carbon balance was -330.09 g C m(-2); then it was carbon sink in 2019. By fully utilizing climate resources and improving agricultural managements, carbon sink is increased in farmland ecosystems.Research highlights: Soil respiration rate and composition were influenced and controlled by the synergistic effect of soil temperature and water content; the maize farmland ecosystem is carbon sink.