ABSTRACT Organic amendments could improve soil nitrogen (N) availability and transformation characteristics, which decreases the N loss within soil profile induced by N excessive application. A field experiment was designed in Shiqiang village with different organic amendments in 2018: (i) control (CK); (ii) chemical fertilizer (NPK); (iii) 1200 kg C ha−1 plus NPK (NPKM) and (iv) 40 kg humic acid ha−1 plus NPK (NPKH). Compared with NPK treatment, in 0–30 cm soil, NH4 +-N content in NPKM and NPKH treatments was increased by 9.15% and 13.36% and NO3 – N content was increased by 11.44% and 12.85%, respectively, while in 30–60 cm soil, NO3 – N content in NPKM and NPKH treatments was decreased by 13.51% and 8.54%, because organic amendments inhibited N leaching to deeper soil. Soil urease and invertase activity in NPKH treatment was 9.52% and 8.31% higher than that in NPK treatment, which was decreased with the decreasing soil depth. The grain yield was increased by 14.17% and 23.87% in NPKM and NPKH treatments, respectively. Thus, humic acid fertilizer was better in increasing wheat yield by improving N transformation and enzyme activities, which could increase wheat N uptake and inhibit N loss in North China Plain.