Agricultural Policies, Crop Type, Tillage Systems and Fertilization as Drivers of Soil Carbon Sequestration in Romania

Soil carbon (C) sequestration is a key component of European climate change mitigation strategies, and it forms part of the Common Agricultural Policy (CAP) and Good Agricultural and Environmental Conditions (GAEC) standards. Using national data for Romania (2005–2024), this paper aims to quantify how crop type, tillage system (conventional, minimum-till and no-till), and nitrogen fertilization influence soil humic carbon (Ch) in wheat, maize, sunflower and rapeseed cropping systems. Carbon inputs from residues, roots, and rhizodeposition were calculated in R based on Intergovernmental Panel on Climate Change (IPCC) coefficients, then tested in Statistical Package for the Social Sciences (SPSS) (factorial ANOVA, multiple regression, Pearson correlations). The results showed that both crop type and tillage systems significantly influence humic carbon values, with the highest values obtained in oilseed crops and in conservation systems (minimum-till and no-till). Among the quantitative factors, nitrogen fertilization had the most pronounced positive effect on carbon fluxes, while yield and precipitation had less influence. The conclusions indicate that the adoption of conservative soil management, in line with CAP objectives and GAEC standards, can support the increase of carbon stocks, with the need for contextual assessment of economic performance and pedoclimatic conditions.