Background and aims <p>Legume residues are important organic inputs, but their effects depend on residue chemistry and application rate. This study examined how pea (<i>Pisum sativum</i>) and field bean (<i>Vicia faba</i>) residues with contrasting phytochemical compositions influenced soil functioning and subsequent barley growth, assessing how residue quality and dose shape soil responses.</p> Methods <p>A sandy loam soil was amended with residues from four legume genotypes with contrasting phytochemical profiles but similar C:N ratios, applied at low (5 t ha⁻¹) and high (20 t ha⁻¹) rates. Unamended and mineral fertilization treatments were included for comparison. Barley was then grown in a microcosm setup for 8&#xa0;weeks, and soil CO₂ efflux, microbial biomass C, inorganic N dynamics, and plant biomass were assessed.</p> Results <p>High-dose applications substantially increased cumulative CO₂ emissions but led to reduced microbial biomass, lower nitrate availability, and significantly suppressed barley growth, particularly for high-phenolic genotypes. In contrast, low-dose low-phenolic residues increased microbial biomass, promoted nitrification, and supported barley growth comparable with mineral fertilizers. Phenolic-rich residues maintained higher ammonium levels and showed reduced microbial and plant responses, indicating inhibitory effects of certain phytochemicals on soil processes.</p> Conclusion <p>Residue impacts on soil processes and crop performance depend strongly on both phytochemical composition and application rate. Low-phenolic residues applied at moderate doses have positively impacted microbial functioning, nitrogen cycling, and barley biomass, whereas high doses, especially of high-phenolic material, were detrimental to microbial activity and plant growth. Integrating residue chemistry into nutrient management could enhance the sustainability of legume-based cropping systems.</p>