THE INFLUENCE OF SOIL ORGANIC CARBON, MOISTURE AND TEMPERATURE ON SOIL SURFACE CO2 EMISSION IN THE 10TH YEAR OF DIFFERENT TILLAGE-FERTILISATION MANAGEMENT

The study was designed to assess the temporal variability in CO2 emission from the soil surface during a crop growing season tinder field conditions, and how these emissions are related to tillage, fertilisation and their interactions in the 10th year of soil management practice. We also aimed to determine if a relationship exists between CO2 emission and soil moisture content, soil and air temperature. The data revealed that in a loam-textured soil during a 10-week period the mean CO2 emission in direct drilled plots (NT) was by 54 and 36% higher than in conventional tillage (CT) and reduced tillage (RT), respectively, while in the soil with a sandy loam texture CO2 emission tinder NT was by 15 and 9 % lower than in CT and RT. Increased fertilisation level (primarily N application) determined an increase in CO2 emission in both loam and sandy loam soils. Moderate rates in loam soil increased CO2 emission on average by 12% and high rates by 24% compared to the emission in unfertilised soil. Fertilisers influence in sandy loam soil was similar. Moderate rates increased CO2 emission on average by 12% and high rates by 27% compared to the emission in unfertilised soil. Growth of soil organic carbon (SOC) content by 0.10% conditioned CO2 emission expansion by 0.82 mu mol mol(-1) in loam soil. However, the same growth of SOC content in the sandy loam soil caused CO2 emission expansion only by 0.34 mu mol mol(-1). Moreover, low content of SOC (< 1.00%) had a weak and uncertain influence on CO2 emission character. The higher the soil moisture content (SMC) was the higher the emission was obtained. However, the same SMC in soils with different texture caused unequal CO2 emission. SMC: range from 13.00 to 16.60% in the soil with sandy loam texture conditioned CO2 emission higher by 28% compared to the emission in the similar moisture conditions in the soil with loam texture. The variation of soil temperature from +10 to +23 degrees C did not significantly influence soil CO2 emission rate.