Modeling soil organic carbon dynamics in an Austrian long-term tillage field experiment

Abstract

An assessment of soil management impacts on carbon dynamics requires easily applicable tools. The carbon balance model CCB was applied to quantify the impact of different tillage systems on soil organic matter (SOM) dynamics. The model was able to describe the observed dynamics of SOM for conventional tillage (CT), but the correct simulation of ploughless soil management in the minimum tillage (MT) treatment required an adaptation of the calculation of the specific turnover conditions that are quantified as Biologic Active Time (BAT). We hypothesized a texture dependent reduction of the turnover activity with depth and calculated a site specific correction factor for the BAT of minimum-tilled soils where the topsoil is not mixed by ploughing. Without additional calibration we evaluated this approach using the data set of the field experiment in Fuchsenbigl (Austria) that was started in 1989 on a fine-sandy loamy Haplic Chernozem (FAO, 2006). The model predicted a reduced turnover activity with a BAT of 13dyr−1 for the MT treatment versus 23dyr−1 for the CT treatment having significant correlations between the modeled pool size of active SOM and the microbiological properties substrate induced respiration and potential nitrogen mineralization.