Related Experiment Video
Updated: Jun 6, 2025

Measuring Phosphorus Release in Laboratory Microcosms for Water Quality Assessment
Published on: July 22, 2019
Limitations of soil-applied non-microbial and microbial biostimulants in enhancing soil P turnover and recycled P
Michelle Natalie Herrmann1, Lydia Grace Griffin1,2, Rebecca John1,3
1Institute of Crop Science, Department of Fertilization and Soil Matter Dynamics, University of Hohenheim, Stuttgart, Germany.
Introduction:
Phosphorus recovery from waste streams is a global concern due to open nutrient cycles. However, the reliability and efficiency of recycled P fertilizers are often low. Biostimulants (BS), as a potential enhancer of P availability in soil, could help to overcome current barriers using recycled P fertilizers. For this, a deeper understanding of the influence of BSs on soil P turnover and the interaction of BSs with plants is needed.
Methods:
We conducted an incubation and a pot trial with maize in which we testednon-microbial (humic acids and plant extracts) and microbial BSs (microbial consortia) in combination with two recycled fertilizers for their impact on soil P turnover, plant available P, and plant growth.
Results And Discussion:
BSs could not stimulate P turnover processes (phosphatase activity, microbial biomass P) and had a minor impact on calcium acetate-lactate extractable P (CAL-P) in the incubation trial. Even though stimulation of microbial P turnover by the microbial consortium and humic acids in combination with the sewage sludge ash could be identified in the plant trial with maize, this was not reflected in the plant performance and soil P turnover processes. Concerning the recycled P fertilizers, the CAL-P content in soil was not a reliable predictor of plant performance with both products resulting in competitive plant growth and P uptake. While this study questions the reliability of BSs, it also highlights the necessity toimprove our understanding and distinguish the mechanisms of P mobilization in soil and the stimulation of plant P acquisition to optimize future usage.
Related Concept Videos
Environmental Applications of Microorganisms
The Phosphorus Cycle
Key Elements for Plant Nutrition
The Roles of Bacteria and Fungi in Plant Nutrition
Bioremediation
Metabolism of Chemolithotrophs

