Possibilities of re-use of spent shiitake (Lentinula edodes (Berk.) Pegl.) mushroom substrate as an additive to the soil for blueberry growing

Abstract

The efficiency of using spent shiitake mushroom substrate (SMS) (Lentinula edodes (Berk.) Pegl.) for soil fertilization in blueberry cultivation technology has been investigated. A comparative analysis of the chemical composition of SMS and peat, as well as the chemical composition of the soil after their application for three years, was conducted. The study also assessed the microbial population and the content of total microbial biomass, as well as the direction of microbiological processes in the soil. In terms of chemical composition, SMS showed comparable results to peat, with a pH of 3.7, moisture content of 58–59%, organic matter content (expressed as Carbon) of 48%, total Nitrogen content of 1–1.7%, and a C:N ratio of 44.7–51.8 :1. Additionally, the SMS contained 0.43% total potassium, 0.37% total phosphorus, 0.42% calcium, and 0.17% magnesium. The evaluation of agrochemical and physical parameters of the loamy-podzolic soil after the application of SMS and peat showed that they were mostly at the same level. However, the soil treated with SMS exhibited advantages in organic matter content, nitrate nitrogen, water-soluble calcium, magnesium, sodium, and electrical conductivity, being 1.5–3 times higher compared to peat application. The results of the microbiological study indicated that the total microbial biomass and the number of microorganisms of the main ecological-trophic groups were higher in the soil with SMS application compared to the soil treated with peat. The introduction of SMS increased the population of mycelial organisms, such as micromycetes by 4.1 times and actinomycetes by nearly three times. Moreover, the application of SMS resulted in the deceleration of destructive processes in the loamypodzolic soil due to the presence of available sources of carbon and nitrogen for plants and microorganisms. This was evidenced by a 1.6-fold decrease in the coefficient of oligotrophy and a 1.4-fold decrease in pedotrophy. Based on the obtained data, the application of spent shiitake mushroom substrate for fertilizing loamy-podzolic soil was found to be beneficial, showing a positive impact on agrochemical and biological properties of the soil.