Combined application of organic manure and reduced-rate chemical fertilizer improved growth , nutrient use efficiency, biomass accumulation, and carbon sequestration of Zanthoxylum armatum seedlings

The possibility of incorporating organic manure (OM) to reduced rates of chemical fertilizers to augment biomass production and carbon sequestration (C-seq) and the role of nitrogen (N), phosphorus (P), and potassium (K) uptake in vegetation C-seq were investigated through pot experiment with 1-year-old Zanthoxylum armatum seedlings. Seven treatments were designed, including NPK, PK, NP, NK, OM, MNPK (50% NPK + 50% OM), and control (CK, no fertilization). MNPK application improved nutrient uptake of 2.76-fold N, 3.34-fold P, and 2.01-fold K, resulting in the highest biomass production and biomass C-seq (1.65-fold) as compared to CK. Correlation and redundancy analysis revealed that C-seq is significantly associated with biomass production (r = 0.994) and regulated by N and P uptake. The highest nutrient use efficiency was recorded for N (38.8%), followed by K (21.1%) and P (16.4%) under MNPK application. Therefore, MNPK could be an optimum measure regarding fertilizer saving, biomass production, and attaining C neutrality.