Soil carbon dioxide emissions in eggplants based on cover crop residue management

In this study, cover crop residue management as a strategy to identify agricultural practices suitable for increasing soil carbon (C) storage and contributing to the mitigation of CO(2)in a cover crop-eggplant sequence was evaluated. The treatments applied were: (a) four winter managements [three cover crops (hairy vetch, oat and oilseed rape) and a bare soil]; and (b) three residue managements [residues incorporated into the soil at a depth of 0.3 m as deep tillage (DT), residues incorporated into the soil at a depth of 0.1 m as shallow tillage (ST), and residues left on soil surface (RS)]. Eggplant biomass and C content, soil CO(2)flux, soil temperature and moisture were measured. Hairy vetch under DT showed the highest emission rate during the eggplant cultivation. At eggplant harvest time, CO2-C emissions were high in hairy vetch, intermediate in oat and oilseed rape, and low in bare soil (5.4, 4.2 and 3.3 Mg ha(-1), respectively). Among residue managements, CO2-C emissions were higher in ST and DT than in RS (4.5 vs. 3.7 Mg ha(-1), respectively). Despite contributing to the highest soil CO(2)flux, the decomposition of hairy vetch residues supports the production of eggplant crop, as it is shown by the carbon input/output ratio, especially under RS conditions representing a temporary sink of CO2-C. As a system, hairy vetch RS is the most productively sustainable because it is simultaneously yielding the high eggplant crop biomass and retaining C residues in the soil.