Soil amendment with MnO2-modified compost improves plant growth and the rhizosphere ecology

Abstract

To investigate the short-term effects of MnO₂-modified compost on early plant growth and rhizosphere microecology, a pot experiment was conducted using radish seedlings as the model plant. Treatments included unamended soil, soil amended with different application rates of unmodified compost, and soil amended with MnO₂-modified compost. Plant growth performance, leaf photosynthetic pigments, rhizosphere soil physicochemical properties, and microbial community characteristics were systematically analyzed. The results showed that compost application promoted early growth of radish seedlings, with the MnO₂-modified compost exhibiting the most pronounced effects. This treatment significantly increased plant biomass as well as chlorophyll and carotenoid contents, thereby enhancing photosynthetic potential. Meanwhile, the application of MnO₂-modified compost markedly increased rhizosphere soil organic matter, total nitrogen, and available phosphorus contents, while decreasing the C/N ratio. High-throughput sequencing and PICRUSt2-based functional prediction analyses indicated that MnO₂-modified compost altered the structure of rhizosphere bacterial and fungal communities and affected predicted functional potentials related to organic matter degradation and nutrient cycling. These findings suggest that MnO₂-modified compost, particularly M5, was associated with improved early seedling growth, higher rhizosphere TKN and AP contents, and shifts in rhizosphere microbial communities. However, because the experiment lasted only 17 days and Mn speciation, Mn bioavailability, enzyme activities, inorganic nitrogen fractions, phosphorus fractions, and nutrient transformation rates were not directly measured, the underlying mechanisms and long-term agronomic effects require further verification through longer-term pot experiments and field trials.