Enhancing Wheat Nitrogen Uptake through the Combined Use of Crop Residues and Nitrification Inhibitors

Nitrification inhibitors (NIs) effectively reduce nitrogen (N) loss and enhance fertilizer use efficiency, leading to higher yields. While both NIs and crop residues reduce nitrification, their combined effects on N availability from different sources (soil, fertilizer, and residue) and plant uptake require further investigation. This study utilized a ¹⁵ N double-labeling field experiment ( ¹⁵ N-labeled residue with nonlabeled fertilizer and ¹⁵ N-labeled fertilizer with nonlabeled residue) to assess these effects. The treatments included ( ¹⁵ NH ₄ ) ₂ SO ₄ with and without 3,4-dimethylpyrazole phosphate (DMPP) at two residue levels. The measured parameters included soil mineral N availability ( ¹⁵ N-NO ₃ ⁻ and ¹⁵ N-NH ₄ ⁺ ), ¹⁵ N recovery, and yield components. The results indicate that NIs significantly increased wheat grain and straw yields only at 10 t ha ^− 1 residue application. The combined use of NIs and residues increased the available N from all three sources (fertilizer, soil, and residue). Regarding nitrogen use efficiency from the fertilizer source, NI is effective at all residue levels. Concerning nitrogen use efficiency from the residue, NI does not affect it. Residue application alone was insufficient to meet crop N demand, but its utility improved significantly when it was supplemented with chemical fertilizers. Additionally, the combined effect of NIs and residues mitigated the inhibitory processes associated with nitrification suppression. In conclusion, if farmers incorporate wheat residues into the soil through plowing, applying NIs is recommended to maintain yield and nitrogen use efficiency.