New soil test may help reveal how microbes make phosphorus available to plants

Scientists have developed a simpler and more affordable method to measure a biologically active form of phosphorus in soil, potentially offering new insights into how soil microbes help plants obtain the nutrient.

Phosphorus is essential for plant growth and food production, but natural reserves of the nutrient are finite. Understanding how phosphorus is stored, transformed and released in soil could help maintain agricultural productivity while reducing nutrient waste and environmental impacts.

An international research team involving scientists from Sultan Qaboos University, the James Hutton Institute, Oman’s Environment Authority and other institutions refined a laboratory technique for measuring DNA-bound phosphorus, or DNA-P, in soil, according to a study published in the Journal of Agricultural and Marine Sciences.

DNA-P is part of the organic phosphorus pool associated with living microorganisms. Soil microbes continuously absorb, transform and release nutrients, making DNA-P a potential indicator of the biologically active part of the soil phosphorus cycle.

The researchers modified an existing analytical method and tested it on 32 soil types collected from across the United Kingdom. They found that the revised procedure was easier and less costly while maintaining the accuracy and sensitivity required for reliable measurements.

A major improvement involved removing enzyme treatments that had previously been part of the testing process. The researchers found the treatments were unnecessary, allowing the procedure to be simplified and reducing its cost.

However, ultrafiltration remained an essential part of the process because it separates DNA-bound phosphorus from other phosphorus-containing compounds. Without this step, measurements of DNA-P could be less accurate.

The study found that DNA-P accounted for only a small portion of total organic phosphorus in the tested soils. However, its levels were strongly associated with soil pH, microbial biomass phosphorus, organic matter and phosphorus dissolved in soil water.

The findings indicate that DNA-P may be more closely linked to living soil microorganisms than to stable, long-term phosphorus reserves. It could therefore provide researchers with a useful indicator of the more active part of the soil phosphorus cycle.

The improved testing method could make it easier for scientists to study biologically active phosphorus and better understand how soil microbes influence the amount of phosphorus available to plants.

With agriculture facing increasing pressure to use limited phosphorus resources more efficiently, the method could support future research into soil fertility, nutrient management and more sustainable farming practices.

Source: Science Daily