Seasonal Dynamics of CO2 Fluxes in Two Central-Russian Agroecosystems with Contrasting Ecological and Agronomic Conditions

Abstract

An eddy covariance (EC) GHG study was conducted at two comparable agroecosystems in the Central region of European Russia. The study was conducted in 2013 at the RTSAU Experimental Field with Umbric Albeluvisols (Moscow) and a private farm field with Chernozems in the Pristen area (Kursk region). Both studies involved barley crops, but the fields differed in climate, soil and technological conditions. Diurnal values of net ecosystem exchange (NEE) were two times higher in Kursk than in Moscow. The higher gross primary production (GPP) in Kursk was characterized by better climate and soil conditions and, partially, by the low intensity practices of semi-organic farming. GPP dynamics of the two agroecosystems were significantly different only during the first 50 days of vegetation; however, NEE seasonal differences persisted throughout the growing period, with the trends changing until the end of barley ripening. General trends for ecosystem respiration and GPP were determined by the crop phase. NEE seasonal dynamics showed that the Chernozem agroecosystem was characterized by an almost 2-fold increase in the range of CO2 fluxes, largely determined by hydrologic regime features. Since yield in Kursk was 50% lower than that in Moscow, it may be concluded that the use of modern fertilizing and crop protection systems converts a larger portion of GPP into yield mass.