Organic fertilizers increase the proportion of saprotrophs favoring soil nitrification under medicinal plants Fritillaria thunbergii

Abstract

The level and form of nitrogen supply are key factors affecting the yield and quality of traditional Chinese medicinal plants. However, it remains unclear how soil nitrogen supply levels and forms are modulated by microbial functional groups through the application of different types of basal fertilizers in medicinal plant cultivation. This study compared the impacts of soluble fertilizer, slow-release fertilizer and chicken manure, both individually and in combination, on fungal composition and NH₄⁺/NO₃⁻ ratio in soils cultivated for Chinese medicinal plants Fritillaria thunbergii. There are substantial differences in fungal community composition between organic and inorganic fertilization. Organic fertilization enhanced the abundance of Pezizales by 10 folds and decreased the abundance of Hypocreales by 51 % compared with the control. All fertilization (inorganic and organic) decreased the proportion of pathotrophic fungi by 70 %, while organic fertilizers increased the proportion of saprotrophs (orders Sordariales and Pezizales). Fertilization increased the activity of leucine aminopeptidase by 87 %, while organic fertilization counteracted a reduction in urease activity compared with inorganic fertilizer treatments. Both inorganic and organic fertilization decreased soil NH₄⁺/NO₃⁻ ratio by 64 % and increased the bulb yield by 6.8 times, and the lower soil NH₄⁺/NO₃⁻ ratio is favorable for the yield of bulbs. The study indicates that the use of organic fertilizers has a good perspective to maintain soil health and high bulb yield via promoting the proportion of saprotrophic fungi.