Application of composted lipstatin fermentation residue as organic fertilizer: Temporal changes in soil characteristics and bacterial community

Lipstatin fermentation residue (LFR) is a byproduct of the pharmaceutical industry that may be disposed through land application after composting due to its high organic matter content. The effect of composted LFR application on the soil properties and microbial community still needs to be investigated before field application to verify its suitability and safety. Over a three months laboratory soil incubation experiment, the impacts of composted and raw LFR on soil properties, enzyme activities and bacterial community were investigated. The results indicated that the pH value of the soil fertilized with composted LFR decreased slightly, but the EC value increased significantly. It was worth noting that there was no measurable accumulation of lipstatin with LFR fertilization. The soil nutrients including available phosphorus, available potassium, organic matter and soluble organic matter were significantly increased in composted LFR-fertilized soil. In addition, the culturable microorganisms and enzymes were not inhibited throughout the incubation of composted LFR in soil. The composted LFR improved the soil fertility, environment and microbial biomass, which demonstrated its potential as a fertilizer. This study will provide a theoretical basis for the resource utilization of LFR.