Soil organic carbon data comparison after 85 years and new 13C/12C compositions: The case study of the Ferrara province (Northeastern Italy)

Abstract

The main causes of soil organic matter (SOM) loss are land use (e.g., conventional agriculture) and land-use change (e.g., conversion of wetlands into croplands). Before World War II and until 1960s, the Ferrara province in the Emilia-Romagna region (Northeast Italy) enlarged its agricultural production area through drainage of wetlands. After that, the newly drained area was put into intensive agricultural production with practices that proved to be unsustainable, and whose negative effects (depletion of soil organic carbon [SOC] and emissions of greenhouse gases [GHGs], e.g., CO₂) have never been quantified. In this work, we estimated the changes in SOC 85 years after the drainage of the palustrine environment, by comparing 1937 SOC measurements with those made in 2022. Comparison of SOC maps from 1937 and 2022 indicates that most of the area suffered a significant SOC loss (∆OC_85 years from 0.05 to 18.57 wt%), except for northern areas in which the peat nature of the soil has been preserved. We also measured the ¹³C/¹²C on the 2022 soil samples and generated a present-day map of the SOC isotopic ratios, which could be used in future as a benchmark to evaluate changes in soil carbon stocks and fluxes.