Soil pH

AUS-TMS-AGR-SPH General Moderate confidence

Benchmark Value

7 pH
Thresholds: Lower: —, Upper: 7
Direction: Lower is desirable ↓
Form: UpperThreshold

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 10 benchmarks together — the OptimalRange form drives the primary score, while 9 guard(s) constrain the result.

Evidence & Context

While an upper detrimental threshold for ecological health due to over-management (e.g., over-liming) could be considered if pH (CaCl₂) consistently exceeds approximately 7.0 to 7.2, this is not the primary management concern.

Metric Definition:

Soil pH measured in 0.01M CaCl₂, indicating the upper detrimental threshold beyond which ecological health may be harmed due to over-liming or excessive alkalinity.

Benchmark Definition:

Upper detrimental soil pH threshold measured in 0.01M CaCl₂ above which micronutrient deficiencies and ecological harm may occur.

Justification:

Above this level, micronutrient deficiencies (Fe, Mn, Zn, Cu, B) become a significant concern for many crops and could impact plant community health and soil biology.

Sources (1)

Preview of Effects of agricultural management on soil carbon and pH in the Douglas Daly region of the Northern Territory - NT (Book), accessed on June 7, 2025
Effects of agricultural management on soil carbon and pH in the Douglas Daly region of the Northern Territory - NT (Book), accessed on June 7, 2025 Journal

General soil science principles and reviewed literature

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Supporting Sources (1)

Additional references from the underlying research that informed this benchmark.

Preview of Cotton Production and Sustainability in the Northern Territory: A Comprehensive Analysis of Yield, Soil Properties, and Cover Crops (Mwando et al., 2024, In: Proceedings of the 21st Australian Agronomy Conference)
Cotton Production and Sustainability in the Northern Territory: A Comprehensive Analysis of Yield, Soil Properties, and Cover Crops (Mwando et al., 2024, In: Proceedings of the 21st Australian Agronomy Conference)
Direct Evidence Journal

Cotton Production and Sustainability in the Northern Territory: A Comprehensive Analysis of Yield, Soil Properties, and Cover Crops (Mwando et al., 2024, In: Proceedings of the 21st Australian Agronomy Conference)

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Context

  • Region Australia
  • Biome Tropical Monsoonal Savannas
  • Land Use Agricultural Crop Production
  • Assessment Pristine Reference
  • Evidence Type DegradationThreshold

Lifecycle

  • Status Active
  • Version 1
  • Effective From 25 Mar 2026

Notes

Evidence for naturally occurring or management-induced detrimental high pH in broadacre cropping on these savanna soils is limited.