Soil organic carbon stocks and dynamics under contrasting organic matter management practices – Results from a 65-year-old experiment in Belgium
Year: 2025
Type: article
Abstract: In the context of climate change, long-term field experiments (LTEs) are key ressources to evaluate the long-term effects of agricultural practices on soil carbon storage potential. The objectives of this work were twofold: (i) to assess the long-term effects of animal manure (cattle manure and pig slurry), aboveground crop residues restitution and cover cropping, alone or in interaction, on soil organic carbon (SOC) stocks in the topsoil and subsoil; and (ii) to evaluate the temporal dynamics of SOC in the topsoil in relation to these management practices.To achieve these goals, we sampled soil cores in a 65-year-old LTE dealing with contrasting organic matter (OM) management practices located in the silt loam region in Wallonia, Belgium. Five soil layers were sampled at 0-10, 10-25, 25-33, 33-55 and 55-80 cm depths. For the unbiaised comparison of treatments, SOC stocks were calculated from SOC content and bulk density measurements with the equivalent soil mass (ESM) method. To evaluate SOC temporal dynamics, we analyzed historical data of annual SOC measurements in the topsoil (0-25 cm). Three indicators of SOC evolution were calculated: the linear regression slope between relative SOC contents compared to the control treatment and years, net SOC increase and response ratio (Rr). This analysis was conducted over three periods during which the mineral nitrogen (N) fertilization management strategy remained unchanged, allowing for comparisons among treatments under similar conditions. This methodology enabled us to analyze the influence of N as a confounding factor.Additional C storage in the topsoil occured in treatments receiving animal manure, resulting in net SOC increases ranging from 16 to 26% over a period of 63 years. However, there were not significant net increases in treatments that restituted crop residues alone (5%) or used cover crops in combination with crop residues restitution (12%). Nevertheless, these treatments have effectively prevented SOC loss compared to the control treatment which showed a 4% decrease during the same period. In the subsoil, there were no significant differences in SOC stocks among the six treatments.This study showed that (i) the quantity and quality of the OM inputs play a crucial role in SOC storage, (ii) the increase in N fertilization over time and the adjustments between the treatments affected SOC storage, (iii) measuring initial SOC contents is essential when evaluating SOC stock and content change rates.
Source: European Journal of Agronomy
Institution: Walloon Agricultural Research Centre
Language: English
Subfield: Soil Science
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $3,200
OpenAlex ID: W4411328891