Improvement of Tea Yield and Quality by Chicken Manure and Wine Lees (CMWL) Substitution for Chemical Fertilizers in the Hilly Region of Western Sichuan, China

Currently, many organic materials, due to their high content of organic matter, can partially replace chemical fertilizers to enhance soil quality and crop yield. However, the effects of replacing different ratios of chemical fertilizers with organic materials made from chicken manure and wine lees (CMWL) on soil and tea quality are not well known. Therefore, via a 2-year field study, this study used CMWL to replace 25% (T1), 50% (T2), and 75% (T3) (based on phosphorus fertilizer) of chemical fertilizer to understand how soil nutrients, tea yield, and quality would be affected. Compared to chemical fertilizer (CF), CMWL inclusion increased the soil pH by 0.08–0.17 in the 0–20 cm soil layer and 0.02–0.07 in the 20–40 cm soil layer for 2 years. Second, the growth rate (increase per year) of soil organic matter (OM) in the 0–20 and 20–40 cm soil layers reached 7.01 and 4.55%, respectively. The T2 and T3 treatments enhanced soil total nitrogen (TN), phosphorus (TP), and potassium (TK) in both 0–20 and 20–40 cm layers. However, the T2 treatment significantly increased the soil available nutrients, tea yield, water extracts, tea polyphenols, amino acids, and caffeine. Finally, the partial least squares (PLS) analysis showed that OM and available phosphorus (AP) were the main factors affecting tea yield and quality. Therefore, the T2 treatment was the best fertilization scheme for tea production. This study provides information on partially replacing chemical fertilizers with CMWL to elevate soil fertility, thereby promoting tea quality. • Chicken manure and wine lees (CMWL) replacement improved soil and tea quality. • 50% CMWL replacement had the best effect on improving soil nurients and tea quality. • Applying CMWL to enhanced soil nutrients is an effective way to improve tea quality. • Organic matter and avliable phosphorus were the main factors affecting tea quality.