Influence of tillage systems on short-term soil CO2 emissions

Abstract

Agricultural ecosystems can play a significant role in greenhouse gas emissions, specifically, carbon dioxide. Tillage management can increase atmospheric CO2concentrations and contribute to global warming but it is uncertain to which extent tillage enhances the transfer of soil CO2 to the atmosphere. Our objectives were (1) to determine short-term, tillage-induced soil CO2 emissions; (2) to determine the effect of different tillage systems and time after tillage operation on soil CO2emissions and soil microclimate and (3) to examine the relations between short-term soil CO2 emissions and microclimate (soil temperature, soil water content; air temperature and relative air humidity). Soil CO2 concentrations were measured on Stagnic Luvisols, in a temperate continental climate of the central lowland Croatia in October 2013 before, zero and three hours after tillage operations with in situ closed static chamber method. The four tillage systems were no-tillage (NT), ploughing to 25 cm (P25), very deep ploughing to 50 cm (P50) and subsoiling to 50 cm (PS50). The study showed that tillage has impact on soil CO2 emissions and soil microclimate. Tillage has accelerated the transfer of soil CO2 to the atmosphere but soil CO2 emissions declined sharply within three hours after tillage operations. Soil temperature has decreased after tillage operation and afterwards continued to rise while soil water content has been decreasing during whole study period. Correlations between soil CO2 emissions and microclimatic factors were mostly weak or modest while best type of studied correlations between soil CO2emissions and microclimate showed to be the second order polynomial correlation.