Preparation of Biofertilizer with Phosphogypsum and Straw: Microbial Community Changes and Plant Growth Effects

Purpose The accumulation of solid phosphogypsum waste poses a great ecological threat. Phosphogypsum is an industrial waste, but the main way of dealing with this waste is still accumulation. This is not only a waste of land but also pollutes the environment. However, environmental problems exist in the treatment of phosphogypsum via physical and chemical methods, and this study aims to present a new environmentally friendly method to treat phosphogypsum and promote its comprehensive utilization. We analyzed the microbial community changes that occur in the phosphogypsum composting process and determined the feasibility of utilizing the biofertilizer prepared in this study through plant experiments. Methods Biofertilizers were prepared by combining phosphogypsum with waste biomass straw and livestock manure. A composite microbial agent with live bacteria was added to form the finished phosphogypsum biofertilizer after composting. In this study, we simultaneously used high-throughput sequencing and other methods to explore microbial community changes and dominant flora as well as microbial functions. This biofertilizer was applied in plant experiments to test the growth of plants. Results During the course of the experiments, there was an increase in total nitrogen, exchangeable potassium, and soluble phosphorus in the soil. Among soil physical properties, there was also a significant increase in porosity. During the composting process, the dominant bacteria were Actinobacteria, which accounted for 41.82% of the total. However, over the composting process, this group showed a decreasing trend. The application of this biofertilizer in plant experiments resulted in a significant increase in plant growth; the chlorophyll content of biofertilized pakchoi was more than twice as high as that of unfertilized pakchoi, and the vitamin C content of biofertilized ryegrass was more than twice as high as that of unfertilized ryegrass. Conclusion Overall, changes in the dominant flora were found during the composting process, and Actinobacillus was the most stable flora, which showed a decreasing trend but consistently accounted for the highest percentage of bacteria during the experiment. Additionally, plant growth performance was tested, and the parameters included plant height, length, weight, vitamin C and chlorophyll. Without exception, the growth parameters in the plants grown with phosphogypsum biofertilizer were better than those of the control group. The biofert