Soil CO2 emission and organic C dynamics in the lawn constructed soils at the RTSAU field experiment
Dmitriy A. Achkasov, Anna S. Shchepeleva, Andrey V. Stepanov & Ivan I. Vasenev
Russian Timiryazev State Agrarian University, Moscow, Russia
One of principal soil environmental functions is regulation of greenhouse gases fluxes in the terrestrial ecosystems where 60-80 % of CO2 emission usually have soil origin. This soil function is especially crucial in case of urban lawn ecosystems with increased dynamics and spatial variability of soil organic C and CO2 fluxes. We analyzed them in the key objects of 5-year (2012 - 2017) field container experiment with different composition and construction of the man-made lawn topsoil, developed in the Field Experimental Station of the Russian Timiryazev State Agrarian University. Maximum CO2 emissions have been observed in the versions with 20-cm peat horizons in the first year of monitoring (up to 7.7 kg/m2 of CO2). After 2 years of field experiment the lawn topsoil versions with original peat horizons lost up to 70.9% of the primary organic C with close correlation between soil CO2 fluxes seasonal dynamics and soil temperature (R up to 0,89) and/or soil moisture (R up to -0,82). After 3 years of experiment there is observed more or less gradual stabilization of the organic C stocks – with maintenance of statistically significant differentiation in C content, grass productivity and bulk density between originally contrast versions of the experiment. At the fifth year of the field experiment higher values of grass productivity are usually well correlated with topsoil better quality and more intensive biogeochemical cycles of C evaluated by soil CO2 fluxes. Comparative analysis of the principal soil environmental functions in the field container experiment showed best results for the man-made lawn soils with 10-cm and 5-cm peat-sandy horizons. Additional investigations need to evaluate the real possibility of sustainable lawn soil development based on 5-cm layer of peat compounded with sand or sandy loam.