The Influence of Agroclimatic Factors on Soil CO2 Emissions

Darija Bilandžija, Željka Zgorelec, Ivica Kisić

Abstract


There has been a significant increase of atmospheric greenhouse gas (GHG) concentrations since industrial revolution till nowadays. Approximately 10% of total GHG emissions in Croatia belong to the agricultural sector. In this sector, one part of CO2 is released from soil by soil respiration (soil CO2 efflux). Due to these facts, it is of scientists’ interest to determine the influence of tillage treatments on soil CO2 efflux and to determine a relationship between tillage induced CO2 emissions and climatic factors. Field experiment with six different tillage treatments was set up on Stagnic Luvisols near Daruvar (central lowland Croatia). Tillage treatments were: black fallow (BF), ploughing up and down the slope to 30 cm (PUDS), no - tillage (NT), ploughing up and down slope to 30 cm (PAS), very deep ploughing across the slope to 50 cm (VDPAS) and subsoiling across the slope to 50 cm (SSPAS). Soil CO2 efflux was measured using closed static chamber method to quantify soil CO2 efflux during 2012 (n=13) when cover crop was corn. Tillage had a significant effect on CO2 efflux. The lowest average CO2 efflux was determined at the BF treatment with the average CO2 efflux of 29.4 kg ha-1day-1. Comparing the treatments with the cover crop, the highest average CO2 efflux was determined at the NT treatment followed by SSPAS, VDPAS, PAS and PUDS treatment with the average CO2 efflux of 90.9 kg ha-1day-1, 83.5 kg ha-1day-1, 68.9 kg ha-1day-1, 66.7 kg ha-1day-1, 56.0 kg ha-1day-1 respectively. Average CO2 effluxes were moderate positively correlated with soil temperatures at 10 cm depth (r=0.42), moderate positively correlated with air temperature (r=0.45), and non correlated with soil moisture content at 10 cm depth (r=0.08), while strong negatively correlated with relative air humidity (r=0.55). The CO2 efflux was higher during the second half of spring and in the first half of summer while lower CO2 efflux was determined during the period autumn – winter CO2 effluxes were higher in first half of corn growing season than in the second half of corn growing season and the period without the cover crop. Our study suggests that tillage practices have significant influence on soil CO2 emissions.


Keywords*


CO2 efflux, agricultural soil, soil temperature, soil moisture, air temperature, relative air humidity, soil tillage

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