Papers

Summary

Alongside the agricultural development in Brazil, concerns have arisen about its environmental impacts, such asthe emissions of CO2resulting from soil cultivation and management practices in agricultural production sys-tems. The aim of this study was to investigate the temporal variation in CO2emissions and soil physical attri-butes in response to the process of soil particle rearrangement after soil tillage operations. The study wasconducted in three adjacent areas of 10 × 3 m, subjected to two soil tillage systems: (i) rotary hoe +conventional leveling harrow, representing an intensive soil tillage (IT); (ii) disc harrow + leveling harrow,characterizing a reduced tillage (RT). The soil of the third area was not tilled, representing the no-tillage (NT)system. Daily measurements of soil CO2emission (FCO2), soil temperature, soil moisture, pore class distribution,bulk density, penetration resistance, water-free pore space, weighted mean diameter, aggregate stability index,total organic carbon, and particulate organic carbon were performed during a period of 29 days after soil tillage.On thefirst day after tillage, FCO2was 87% higher in the plot under IT (3.86μmol m−2s−1) than RT(2.06μmol m−2s−1) and 147% higher than in the plot under NT (1.56μmol m−2s−1). The variations in soildensity and penetration resistance declined as of the 12th day after tillage. This effect was considered a naturalprocess of soil consolidation and influenced the temporal variation of soil CO2emissions. Pore class distributionis an essential physical attribute to explain the temporal variations of soil CO2emissions, and these classes areinfluenced by the applied management. Therefore, the study of these attributes must be taken into account whenassessing the variation of CO2emissions from agricultural soils.