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 Lower Critical Threshold (Colwell-P, mg/kg): 5-10 mg/kg
Colwell-P test measurement of plant-available soil phosphorus in the top 0-10 cm soil layer.
This benchmark defines the lower critical threshold range of plant-available soil phosphorus in the top 0-10 cm soil layer below which significant impairment of crop growth and soil biological processes is expected in Tropical Monsoonal Savannas under agricultural crop production.
Below this range, significant impairment of crop growth, plant health, and fundamental soil biological processes is expected, even with P-efficient crops and good soil management. Represents a state of critical P scarcity.
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.