Phytoavailability of biosolids phosphorus.

Area of Science:

• Environmental Science
• Soil Science
• Agronomy

Background:

• Efficient phosphorus (P) utilization from biosolids is crucial for sustainable agriculture.
• Phytoavailability of P in biosolids differs significantly based on production methods and composition.
• Understanding these differences is key to optimizing biosolids as P fertilizers.

Purpose of the Study:

• To quantify phosphorus uptake in pasture grass grown in P-deficient soils amended with various biosolids.
• To assess and categorize the relative phytoavailability of phosphorus from different biosolids compared to triple superphosphate (TSP).

Main Methods:

• Greenhouse studies using a common pasture grass in two P-deficient soils.
• Amendment of soils with 12 different biosolids and triple superphosphate (TSP) as a control.
• Measurement of plant P uptake to determine relative phytoavailability.

Main Results:

• Biosolids were categorized into high (>75% of TSP), moderate (25-75% of TSP), and low (<25% of TSP) phytoavailability groups.
• Two biological phosphorus removal (BPR) biosolids demonstrated high P phytoavailability, similar to TSP.
• Most conventional biosolids and some treated BPRs fell into the moderate category.
• Biosolids with high Fe/Al content and high solids (>60%) showed low P phytoavailability.

Conclusions:

• Biosolids P phytoavailability is highly variable, necessitating source-specific assessment for agronomic use.
• Biological phosphorus removal (BPR) processes can yield biosolids with high P phytoavailability.
• Factors like high Fe/Al content and high solids processing reduce biosolids P availability.