Soil Phosphorus
Benchmark Value
Scoring Curve
This curve shows how a field measurement for this indicator would score across all available benchmark forms in this context.
Evidence & Context
Proposed Target Operational Range (Colwell-P, mg/kg): For soils with Low to Moderate PBI (e.g., PBI approximately 70-280), which includes many loamy and some clayey Kandosols and Vertosols: 20-35 mg/kg. For soils with Very Low PBI (e.g., PBI approximately 35-70), often sandy loams or soils with lower P-fixing capacity: 15-30 mg/kg. For soils with Extremely Low to Very Very Low PBI (e.g., PBI C35), typically sandy soils with high leaching potential: 10-25 mg/kg.
Colwell-P test measurement of plant-available soil phosphorus in the top 0-10 cm soil layer.
This benchmark defines the target operational range of plant-available soil phosphorus in the top 0-10 cm soil layer for Tropical Monsoonal Savannas under agricultural crop production, adjusted by soil PBI category to support good crop productivity while minimizing environmental losses.
This PBI-adjusted range aims to support good crop productivity (based on agronomic critical levels for ~90% relative yield) while being managed within a regenerative framework (cover cropping, minimal tillage, organic inputs) to enhance P use efficiency, build soil organic P, and minimize environmental losses.
Sources (1)
Soil phosphorus–crop response calibration relationships and criteria for winter cereal crops grown in Australia - CSIRO Publishing
View SourceSupporting Sources (3)
Additional references from the underlying research that informed this benchmark.
Based on levels indicating severe P deficiency for plant growth and likely impairment of soil ecological functions (e.g., microbial activity, nutrient cycling), drawing from S18, S43, S44, S50 (interpreted for cropping context).
Based on levels where P loss to the environment (leaching/runoff) becomes a significant risk, or where potential for P toxicity or nutrient imbalances may arise. Threshold is highly dependent on soil PBI, texture, and hydrology.
Derived synthesis from 1, S26, S41, S55, S56, S68, with ecological interpretation and adjustment for regenerative principles.