Soil pH — Benchmark Detail

Benchmark Value

7.5 pH

Direction: Higher is desirable ↑

Form: MaximumOnly

Scoring Curve

This curve shows how a field measurement for this indicator would score across all available benchmark forms in this context.

Evidence & Context

Upper Detrimental Threshold: While some savanna soils are naturally alkaline, an increase in pHw significantly above the natural range for a given soil type (e.g., exceeding pHw ~7.5 on typically acidic/neutral soils, or pHw >8.5-9.0 generally, particularly if induced by disturbances like tree clearing) can be detrimental.

Metric Definition:

Soil pH measured in a 1:5 soil:water suspension (pHw)

Benchmark Definition:

Upper detrimental soil pH threshold above which ecosystem health is negatively impacted.

Justification:

Elevated pH beyond natural range reduces micronutrient availability and causes nutrient imbalances, harming pasture productivity and ecosystem balance.

Sources (1)

Preview of Soil nutrient critical limits | MBFP | More Beef from Pastures - MLA, accessed May 13, 2025,

Soil nutrient critical limits | MBFP | More Beef from Pastures - MLA, accessed May 13, 2025, Government

Understanding soil tests for pastures | Soil | Farm management ..., accessed July 17, 2025

View Source

Supporting Sources (37)

Additional references from the underlying research that informed this benchmark.

S11

Direct Evidence

S11

S11

Direct Evidence

S11

S11

Direct Evidence

S11

S11

Direct Evidence

S11

S11

Direct Evidence

S11

S11

Direct Evidence

S11

S11

Direct Evidence

S11

S11, S8

Direct Evidence

S11, S8

S11, S8

Direct Evidence

S11, S8

S11, S8

Direct Evidence

S11, S8

S11, S8

Direct Evidence

S11, S8

S11, S8

Direct Evidence

S11, S8

S11, S8

Direct Evidence

S11, S8

S2, S8

Direct Evidence

S2, S8

S2, S8

Direct Evidence

S2, S8

S2, S8

Direct Evidence

S2, S8

S2, S8

Direct Evidence

S2, S8

S2, S8

Direct Evidence

S2, S8

S2, S8

Direct Evidence

S2, S8

S46, S25

Direct Evidence

S46, S25

S46, S25

Direct Evidence

S46, S25

S46, S25

Direct Evidence

S46, S25

S46, S25

Direct Evidence

S46, S25

S46, S25

Direct Evidence

S46, S25

S46, S25

Direct Evidence

S46, S25

S7, S25

Direct Evidence

S7, S25

S7, S25

Direct Evidence

S7, S25

S7, S25

Direct Evidence

S7, S25

S7, S25

Direct Evidence

S7, S25

S7, S25

Direct Evidence

S7, S25

S7, S25

Direct Evidence

S7, S25

S7, S25

Direct Evidence

S7, S25

Preview of Soil health: looking for suitable indicators. What should be considered to assess the effects of use and management on soil heal - alice Embrapa, accessed July 28, 2025,

Soil health: looking for suitable indicators. What should be considered to assess the effects of use and management on soil heal - alice Embrapa, accessed July 28, 2025,

Contextual Support Journal

www.barenbrug.com.au, accessed May 13, 2025,

View Source

Preview of Soil organic carbon content at a range of north Australian tropical savannas with contrasting site histories - OPUS at UTS, accessed May 16, 2025,

Soil organic carbon content at a range of north Australian tropical savannas with contrasting site histories - OPUS at UTS, accessed May 16, 2025,

Contextual Support Journal

opus.lib.uts.edu.au

View Source

Soil Quality and Its Management in Humid Subtropical and Tropical Environments - UKnowledge, accessed May 15, 2025,

Contextual Support

Soil Quality and Its Management in Humid Subtropical and Tropical Environments - UKnowledge

View Source

Preview of Soil surface pH DSM data of the Southern Gulf catchments (NT and Qld) generated by the Southern Gulf Water Resource Assessment - CSIRO Data Access Portal, accessed May 13, 2025,

Soil surface pH DSM data of the Southern Gulf catchments (NT and Qld) generated by the Southern Gulf Water Resource Assessment - CSIRO Data Access Portal, accessed May 13, 2025,

Contextual Support Government

Gibbons, P., & Sharp, A. (2015). Impacts of warming and fire on soil moisture and available nutrients in a sub-alpine heathland. Climate Research, 64, 159-170.

View Source

Tropical Pasture - Barenbrug Australia, accessed July 18, 2025,

Direct Evidence Journal

P.PSH.1050 – Phosphorus management and requirements of tropical legume pasture swards - MLA, accessed July 18, 2025

View Source

Context

Region Australia
Biome Tropical Monsoonal Savannas
Land Use Livestock Grazing & Pasture
Assessment Conservation Target
Evidence Type DegradationThreshold

Lifecycle

Status Active
Version 1
Effective From 1 Jun 2026

Notes

This threshold is particularly relevant if pH increase is induced by disturbances like tree clearing.

Related Benchmarks

Other benchmarks in the AUS-TMS-LVG-SPH family.