Peat is the key constituent of the growing substrate in horticulture. For the suitability of peat as a growing substrate it is mixed with liming agents, nutrients, surfactants, and perlite among others. The decomposition of peat during its use in horticulture releases CO2 in the atmosphere. While much is known about peat decomposition in aerobic and anaerobic conditions, how peat decomposition changes with horticultural amendments remain unknown. Ascertaining the decomposition process and therefore emissions from them become important to understand carbon footprint of peat use in horticulture. We incubated 11 different treatments of peat with different horticultural additives for a period of 4 months. CO2 emissions from lime+ nutrient-based treatments were highest, followed by treatments with lime+ nutrients+ surfactants+ perlite. Using FTIR measurements we revealed that the lime+nutrients treatments were more humified, followed by lime+ nutrients+ surfactants+ perlite. Our initial observations suggest that the increase in pH and availability of nutrients increases the lability of peat, releases more CO2, and makes the peat more humidified. In contrast, the availability of perlite and surfactants potentially act as a barrier for microbial decomposition and thus show relatively less humification. Compared to the control, horticultural amendments make peat more labile and subject to lose to the atmosphere. While assessing the carbon footprint of the horticulture sector, change in biogeochemistry and enhanced decomposition with horticultural amendments need to be considered. In addition, we demonstrate that the FTIR measurements can reveal small-level changes in the decomposition measures of peat.