Abstract: A three-year (2016—2018) field trial on black soil in northeast China was carried on to investigate the effects of biochar application of 0 (B0), 10 (B10), 30 (B30) and 50 (B50) t hm⁻² on physicochemical properties and dissolved organic matter (DOM) characteristics of black soil. The results showed that the biochar application significantly increased the maize yield, saturated hydraulic conductivity and bioavailability of DOM, whereas it significantly decreased the humification index compared with the control. Compared with the control, the B10 treatment significantly decreased the humic-like substance and chromophoric DOM by 18.7% and 33.1%, respectively. However, the B30 treatment significantly increased the KMnO₄-oxidizable C content, the C management index and the available P content by 35.6%, 36.5% and 39.9%, respectively. Moreover, the B50 treatment significantly increased the electrical conductivity, the leucine amino peptidase (LAP) activity and the ratio of LAP and N-1,4-acetylglucosamine glycosidase to alkaline phosphatase by 21.7%, 22.7% and 27.3%, respectively. In short, an appropriate biochar application (i.e. 30 t hm⁻² in this study area) could enhance both crop yield and soil quality by improving soil water permeability and nutrient availability. While excessive biochar application (i.e. 50 t hm^-2 in this study area) might increase the soil salt content and promote nitrogen transformation and microbial competition for P.