Enhancing Morchella Mushroom Yield and Quality Through the Amendment of Soil Physicochemical Properties and Microbial Community with Wood Ash

<i>Morchella</i> mushroom is a nutritionally rich and rare edible fungus. The traditional cultivation model, which relies on expanding the cultivation area to meet market demand, is no longer sufficient to address the rapidly growing market demand. Enhancing the yield and quality of <i>Morchella</i> without increasing the cultivation area is an intractable challenge in the development of the <i>Morchella</i> mushroom industry. Against this backdrop, this study investigates the effects of different amounts of wood ash (WA) application on the yield and quality of <i>Morchella</i>, and conducts an in-depth analysis in conjunction with soil physicochemical properties and microbial communities. The results indicate that the application of WA improves both the yield and quality of <i>Morchella</i>, with the highest yield increase observed in the WA2 treatment (4000 kg/hm²), which showed a 118.36% increase compared to the control group (CK). The application of WA also modified the physicochemical properties of the soil, significantly improving the integrated fertility index of the soil (IFI, <i>p</i> < 0.05). The soil microbial community structure was altered by the addition of WA. Redundancy analysis (RDA) revealed that pH and total potassium (TK) were the main environmental factors influencing the bacterial community, while pH, TK, and total nitrogen (TN) were the main factors influencing the fungal community structure. In addition, bacterial community diversity tended to increase with higher WA application rates, whereas fungal community diversity generally showed a decreasing trend. Furthermore, the relative abundance of beneficial microbial communities, such as <i>Acidobacteriota</i>, which promote the growth of <i>Morchella</i>, increased with higher WA application, while the relative abundance of detrimental microbial communities, such as <i>Xanthomonadaceae</i>, decreased. Partial least squares path model (PLS-PM) analysis of external factors affecting <i>Morchella</i> yield and quality indicated that WA application can alter soil physicochemical properties and soil microbial communities, thereby improving <i>Morchella</i> yield and quality. Among these factors, soil fertility was identified as the most important determinant of <i>Morchella</i> yield and quality.