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
For sandy soils with Extremely Low to Very Low PBI (e.g., PBI <35-70): Colwell-P levels moderately exceeding the agronomic optimum, potentially > 30-40 mg/kg, should be considered approaching or exceeding a detrimental threshold
soil phosphorus refers primarily to plant-available phosphorus fractions, with a focus on measurements obtained via the Colwell-P test (expressed in mg/kg)
This benchmark represents the upper detrimental threshold of plant-available soil phosphorus (Colwell-P) above which environmental risks such as leaching and runoff increase significantly in sandy soils with low phosphorus buffering capacity under agricultural crop production in tropical monsoonal savannas.
Due to the high risk of P leaching and runoff. For these soils, the capacity to retain surplus P is minimal.
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.