Simplified Soil DNA Test Maps Microbial Phosphorus Across 32 UK Soils

A 2026 study in the Journal of Agricultural and Marine Sciences has refined a laboratory method for measuring phosphorus held in soil DNA. The researchers applied the revised procedure to 32 soils from across the United Kingdom, addressing a part of the organic phosphorus cycle that is difficult to quantify with standard soil tests.

DNA bound phosphorus is associated with living microorganisms and their remains. It can turn over more quickly than stable organic phosphorus, which makes it potentially important for understanding nutrient cycling, but the pool is small and chemically difficult to separate from other phosphorus compounds.

The team first tested individual steps from an earlier analytical protocol on two contrasting soils. It then used the revised method across the 32 soil set and compared the results with phosphorus speciation from phosphorus 31 nuclear magnetic resonance and with standard soil measurements.

The experiments found that enzyme treatments used in the earlier procedure were not necessary for phosphorus recovery. Removing those steps made the method simpler and less costly while retaining precision and sensitivity.

One step could not be removed. Ultrafiltration remained essential because it separated DNA bound phosphorus from other phosphorus containing compounds that would otherwise distort the measurement.

Across the 32 soils, DNA bound phosphorus represented only a small share of total organic phosphorus. Even so, its concentration was significantly correlated with soil pH, microbial biomass phosphorus, organic matter and phosphorus in water extracts.

Those relationships support the interpretation that the measured pool was connected to living soil organisms rather than to long stabilised phosphorus reserves. The result does not create a new field test or a direct fertilizer prescription, and farmers should not use it to change applications without agronomic evidence.

The practical value is a cleaner research tool for studying how microbial communities store and release phosphorus. Further validation under different soils, crops and management systems will be needed before the measurement can inform routine nutrient decisions.