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: 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 (Rs) and composition were influenced and controlled by the synergistic effect of surface soil temperature (Ts) and water content (Wcs). Ts played a leading role, while Wcs played an important role. Ts and Wcs had the greatest influence on the heterotrophic respiration rate (Rh), followed by Rs and autotrophic respiration rate (Ra). 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.