Effects of Zanthoxylum armatum Harvest Residue Incorporation on Soil Properties, Yield, and Fruit Quality

Abstract

The sustainable management of agricultural residues is essential for improving resource utilisation and maintaining soil fertility in plantation systems. This study investigated the potential of composting and applying Z. armatum harvest residues as an organic amendment for soil improvement and crop production. A field experiment with five treatments (CK, T1, T2, T3, and T4) was conducted to evaluate the nutrient characteristics of the different residue components, compositional changes during composting, and the effects of compost application on soil properties, yield, and fruit quality. The results showed that leaves contained higher concentrations of N, P, K, Ca, and Mg than branches and thorns, whereas branches and thorns had higher lignin and cellulose contents. Composting significantly reduced organic carbon, lignin, and cellulose contents while increasing nutrient concentrations, resulting in a more stable, nutrient-enriched organic amendment. The application of composted residues significantly improved soil fertility by increasing soil organic matter by up to 58.7%, alkaline hydrolysable nitrogen by 42%, available phosphorus by 66%, and available potassium by 42%, while reducing soil pH and decreasing bulk density by up to 24.6%. These effects increased with the compost application rate, and the high-rate treatment (T3, 15 t·hm-2) produced the greatest improvement. In addition, residue compost application enhanced the fresh pepper yield, dry pericarp yield, and fruit quality characteristics of Z. armatum. Compared with the control, T3 increased fresh pepper yield by 13.88% and dry pericarp yield by 25.17%, while increasing hydroxy-α-sanshool content to 17.28 mg·g-1, oil yield to 0.78%, and volatile oil content to 8.24 mL·100 g-1. Overall, composting and returning Z. armatum harvest residues to plantations represent an effective strategy for converting agricultural waste into valuable organic amendments, improving soil quality, and promoting the sustainable production of Chinese prickly ash.