Kinetic parameters of soil organic matter decomposition in soils under forest in Hungary

To obtain better knowledge on how soil organic matter (SOM) decomposition is regulated by different soil properties, 13 soil samples amended with maize residues were incubated for 163 days. Carbon mineralization kinetics was modelled by fitting five different kinetic models, from which the first-order two pools model was selected for further analysis. The results showed that residue addition increased the rate of C mineralization, particularly in sand samples, where four times as much C was released as CO2 in amended samples as in control samples. Residue addition also affected the kinetic parameters of the two C pools modelled. The mean residence time (MRT) averaged 31.9 days for the fast C pool and 65.1 days for the slow C pool phase in the amended soils, whereas in the control soils MRT1 and MRT2 averaged 52.3 and 94.2 days, respectively. The kinetics of C decomposition was found to be influenced to the greatest extent by soil organic carbon (SOC) content and soil texture. The texture primarily affected the size of the fast carbon pool (C1): in both the amended and control samples C1 was increased by the clay content (r = 0.574 and r = 0.554, respectively) and decreased by the sand content (r = −0.771 and r = −0.583, respectively). Our results confirm the fact that texture has a significant role in soil organic matter mineralization, however other parameters also play a crucial role in the decomposition due to the complexity of the processes.