Effect of Mineral Nitrogen and Glucose Application on Temperature Sensitivity (Q10) of Soil Organic Matter Mineralization

The temperature sensitivity (Q10) of C mineralization was studied in soils of two types: gray forest (Phaeozem, forest glade ecosystem) and soddy-podzolic (Retisol), dead soil cover pine ecosystem). It is shown that the temperature sensitivity is higher in the forest glade than in the pine forest and increases down the soil profile. Soil depth was found to be the strongest determinant of Q10 variation. Application of nitrogen (NH4NO3) raised Q10 in the upper soil horizons, and application of glucose, on the contrary, lowered Q10 in both ecosystems. The effect of glucose addition was most pronounced in the lower horizons. The combined application of glucose and nitrogen affected Q10, as well as the addition of glucose alone, indicating that the availability of a readily degradable substrate is a stronger factor influencing temperature sensitivity than nitrogen. The data obtained permitted predicting the change in the contribution of the heterotrophic component of CO2 emission from soils during global warming, as well as the increasing influx of root exudates, phytodetritus, and exogenous nitrogen into the soil.