Phosphorus is vital for plant growth, but natural reserves are limited. To manage it sustainably, scientists need to understand how the nutrient moves through soil, including the portion tied up in living microorganisms. A team led by researchers at Sultan Qaboos University, working with the James Hutton Institute and others, has refined a laboratory method for measuring DNA-bound phosphorus (DNA-P) in soil, making it simpler and less expensive without sacrificing accuracy.
The improved method, described in the Journal of Agricultural and Marine Sciences, was tested on 32 soil types from across the United Kingdom. The key change was removing enzyme treatments that had been part of the original procedure. However, ultrafiltration remained a necessary step: it separates DNA-P from other phosphorus compounds, and without it the measurements would be less reliable.
DNA-P made up only a small fraction of total organic phosphorus in the soils studied, yet its concentration showed strong correlations with soil pH, microbial biomass phosphorus, organic matter content, and phosphorus dissolved in soil water. Those links suggest DNA-P is closely associated with living soil microbes rather than stable, long-term phosphorus reserves. That makes it a useful indicator of the biologically active part of the phosphorus cycle.
The new test gives researchers a practical tool for studying how microbial communities influence phosphorus availability to plants. As agriculture faces pressure to use finite phosphorus resources more efficiently, better measurements of this nutrient could support research into soil fertility, nutrient management, and more sustainable food production.