CO2 emissions and chemical properties of Histosols under drainage and liming in a controlled environment

Abstract

Climate change integrates global warming, the water crisis and socio-environmental impacts. Carbon sequestration in the soil is a strategy to mitigate these effects, and Histosols (Organossolos) are important due to their high C stocks. However, they have limitations such as high acidity and low oxygenation, requiring liming and drainage. However, if carried out inappropriately, these operations cause degradation of soil organic matter (SOM) and greenhouse gas (GHG) emissions. The aim was to investigate the effects of combining these practices on fertility, C content, humic fractions and C-CO₂ emissions in Organossolo Tiomórfico from southeastern Brazil. The trial was conducted in a 2 × 3 factorial design (with and without liming × drainage levels: 30, 60 and 90% of field capacity), with 4 replications. The samples were evaluated at two different times (30 days of incubation and another 30 days of incubation). CO₂ release was quantified at regular intervals and C-CO₂ losses were estimated in Mg ha^-1. In each phase, soil chemical attributes and SOM indices were analyzed. The practices adopted altered the carbon content of humic substances, microbial respiration and soil fertility. Fulvic acid contents decreased under lower drainage, and humic acid decreased with CaCO₃ application and waterlogging. Liming increased C-CO₂ emissions, regardless of drainage. C-CO₂ losses were ± 4.1 Mg ha^-1 in the first phase and ± 1.6 Mg ha^-1 in the second phase of the experiment. It can be concluded that liming, in the short and medium term, increases C-CO₂ losses in Histosols.