<p>Ditch-buried straw returning is an effective practice for straw utilization; however, slow decomposition limits its application. This study aimed to investigate how different exogenous nitrogen sources affect the decomposition, nutrient release, and component degradation of wheat straw in a ditch-buried system. Four treatments were established: a control treatment (CK), and three treatments of different exogenous nitrogen application, urea (TUR), chicken manure organic fertilizer (TCF), and ammonium sulfate (TAS), with a C/N ratio of 25. Straw residues were collected periodically over 240&#xa0;days. Exogenous nitrogen significantly enhanced straw decomposition, with organic nitrogen (TCF) showing the strongest effect, achieving 61.00% cumulative decomposition, which was 12% higher than that of CK (49.00%). Nutrient release (N, P, K) was concentrated within the first 30 days. Decomposition and nutrient release followed an accumulated temperature-based first-order kinetic model (R² ≥ 0.99). The degradation rates of cellulose, hemicellulose, and lignin reached 70.25–77.32%, 75.25–82.32%, and 61.79–72.00%, respectively, with TCF demonstrating the highest degradation efficiency across components. While component degradation was best described by a Logistic model (R² ≥ 0.99). Component degradation strongly correlated with decomposition, A combined application strategy of “available nitrogen + organic fertilizer” is therefore recommended to balance decomposition efficiency with long-term effectiveness. These findings provide both theoretical foundation and practical guidance for implementing efficient, high-quality wheat straw returning.</p> Graphical Abstract <p></p>