Soil pH
Benchmark Value
Scoring Curve
This curve shows how a field measurement for this indicator would score across all available benchmark forms in this context. The scoring engine uses 19 benchmarks together — the OptimalRange form drives the primary score, while 18 guard(s) constrain the result.
Contributing Benchmarks
Evidence & Context
Considering this evidence, a lower critical threshold of pH(CaCl₂) 4.5 is proposed.
Lower critical threshold for soil pH below which ecological function is impaired.
This benchmark defines the lower critical soil pH threshold below which ecosystem function is impaired due to increased toxicities and nutrient deficiencies.
Below pH 4.5, aluminium and manganese toxicities and nutrient deficiencies significantly impair ecosystem health.
Sources (2)
Soil acidity | Soil | Farm management - Agriculture Victoria, accessed August 28, 2025
View SourceSoil acidity - Department for Environment and Water, accessed July 30, 2025,
View SourceSupporting Sources (2)
Additional references from the underlying research that informed this benchmark.
Prober, S. M., Lunt, I. D., & Thiele, K. R. (2002). Determining reference conditions for management and restoration of temperate grassy woodlands: relationships among trees, topsoils and understorey flora in little-grazed remnants. Australian Journal of Botany, 50(6), 687–697.
View SourceWorking with bio-amendments: Insights from cropping farmers - Soils For Life, accessed July 7, 2025,
View Source