The influence of tillage, fertilization and meteorological conditions on the CO2 exchange rate in a loamy Cambisol

There is no consensus worldwide concerning the effects of soil management practices on soil net CO2 exchange rate (NCER). The main goal of the study was to determine soil NCER in different agricultural management systems under contrasting meteorological conditions. The evaluation of moisture and temperature (determined by frequency domain reflectometry (FDR) method) impact on total soil NCER was performed. A closed chamber (CC) method using an infra-red gas analyzer (IRGA) was applied. A two-factorial field experiment was established on an Endocalcari-Epihypogleyic Cambisol (CMg-p-w-can) at the Institute of Agriculture, Lithuanian Research Centre for Agriculture and Forestry. A three-year (2009-2012) study revealed that rainy weather conditions suppressed NCER sharply: NCER was 15-fold lower under rainy meteorological conditions than under dry or normal conditions. Soil temperature in both unfertilized tillage systems (conventional tillage, no-tillage) was the main determinant for soil NCER, while this effect was suppressed by the total influence of soil water content, air temperature and amount of rainfall. Soil carbon dioxide flux was slightly (3%) higher under conventional tillage than under no-tillage during dry 2009 and normal 2012 years. In a wet year 2010, conventional tillage increased soil NCER by 70% compared to no-tillage. Fertilization with mineral NPK fertilizers increased soil NCER by on average 32% compared to unfertilized plots, but did not eliminate suppressive effects of meteorological conditions on soil NCER.