GHG emissions: N₂O emissions from crop residues depend on residue characteristics, environmental conditions, and management practices. Residues with a low C/N ratio (<20–30) and high soluble carbon or nitrogen content decompose rapidly, generally increasing N₂O emissions, while residues with a higher C/N ratio (e.g., cereals, maize straw) tend to emit less. Warm, moist, or poorly aerated soils, especially under anaerobic conditions, enhance denitrification and N₂O production, while acidic soils may limit its reduction to N₂. Management strongly influences emissions. Fertilisation practices, soil tillage intensity, and residue placement (surface vs. incorporation) affect both nitrogen availability and oxygen diffusion. Deep incorporation (>15 cm) generally increases emissions compared to shallow incorporation (Aballo et al., 2022). Mitigation strategies are being explored, such as co-applying residues with high C/N materials (e.g., compost, sawdust) or nitrification inhibitors to slow nitrogen turnover and reduce N₂O fluxes. Regarding fertilization practices, applying synthetic nitrogen to crop residues like straw is sometimes done to prevent nitrogen hunger for the following crop and to speed up decomposition, but it may also increase upstream CO₂ emissions and N₂O emissions. Conversely, nitrogen-rich residues can reduce mineral fertilizer needs for the next crop if their mineralization aligns with crop demand. Overall, these effects remain highly context-dependent and require careful management.

Soil organic carbon (SOC): Effects of crop residue incorporation on SOC stocks can range from negative to positive because it depends on how much carbon enters the soil and how quickly that carbon is decomposed or stabilised. Higher amounts of returned biomass generally increase the potential for SOC gains, but the quality of the residues strongly shapes the outcome. Residues with a high C/N ratio or high lignin content decompose more slowly, favouring humification and longer-term carbon storage, whereas residues rich in nitrogen or soluble compounds mineralise rapidly and release more CO₂, reducing the net sequestration effect. Soil conditions (moisture, temperature), microbial activity, and soil texture further influence whether carbon is stabilised or lost. Because these factors interact differently across systems, residue incorporation can lead to outcomes ranging from SOC loss to significant SOC accumulation, with the strongest increases are typically observed in the upper 0–30 cm under long-term, well-managed residue retention.