Intensity of CO2 emissions from sod-podzolic soil at different doses of ameliorants and fertilization of winter rape in Western Polissia

Abstract

Observations by the intensity of CO2 emissions on sod-podzolic soil in the feld of winter rape showed its dependence on fertilizer systems, liming, seasonal dynamics of air temperature, moisture conditions and soil acidity. In summer, there is an increase in the release of carbon dioxide, which is associated with maximum biological activity of the soil. It was found that in the spring rosette phase in variant N120P90K120 with dose 0.5 Ha (by the hydrolytic acidity) of dolomite flour the emission intensity was the highest – 121.3 and 130.1 mg of CO2/kg of soil. The lowest evaporation rate of carbon dioxide (116 mg/kg of soil) was recorded when applying 1.5 Ha doses of dolomite flour on the background of the same fertilizer. The decrease of carbon dioxide emissions in the phase of rape budding and flowering at an air temperature of 15.2–18.4 °С and productive moisture of 10.8–14.6 mm in the 0–20 cm soil layer it was noted. By the addition of dolomite flour decreasing was 5–20 % to the control and 6–23 % to the background of N120P90K120. In these phase of culture vegetation, the lowest CO2 fluxes from the soil (100.9 mg / kg) was observed by the application of dolomite flour at a dose of 1.5 Ha on the fertilization background, while on the control it was 105.7 mg CO2/kg of soil. A similar trend was found in the phase of technical maturity of winter rape. At an air temperature of 28.6 °С and a reserve of productive soil moisture of 9.3 mm (0–20 cm layer), the emission index of carbon dioxide for the specifed dose of liming and fertilizer was at the level of 60.3 mg CO2/kg. It should be noted that in control and variant of N120P90K120 application (background) the decreasing of sod-podzolic soil acidity (pHKCl) to 4.1–4.0 units caused an increase of CO2 production by the soil during the growing season of winter rape. It was proved that the use of dolomite flour at a dose of 1.5 На on the background of N120P90K120 had a more complete neutralizing effect, which helped to reduce the intensity of CO2 emissions by 6.4–22.2 %. Key words: winter rape, CO2 emissions, fertilizers, ameliorants, soil acidity, productivity.