Soil pH

AUS-TDG-AGR-SPH General Moderate confidence

Benchmark Value

No specific value — see range
Range: 5.5 to 6.5 pH
Optimal Range: 5.5 to 6.5
Direction: Higher is desirable ↑
Form: OptimalRange

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

A pH(CaCl₂) range of 5.5 to 6.5 is recommended for achieving maximum phosphorus availability for wheat, ... A broader pH(CaCl₂) range of 5.0 to 7.0 is cited as the zone where most soil microbial activity occurs.

Metric Definition:

Soil pH measured in 0.01M calcium chloride solution (pH(CaCl₂)) indicating the range supporting optimal nutrient availability and microbial activity.

Benchmark Definition:

This benchmark defines the optimal soil pH range for phosphorus availability and microbial activity in temperate agricultural soils.

Justification:

Based on GRDC guidelines linking pH to nutrient availability and microbial health in temperate cropping systems.

Sources (1)

Preview of SECTION 5 Wheat - Nutrition and fertiliser - GRDC, accessed July 8, 2025
SECTION 5 Wheat - Nutrition and fertiliser - GRDC, accessed July 8, 2025 Journal

Grains Research and Development Corporation (GRDC). (2016). GrowNote Wheat South 05 Nutrition.

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Supporting Sources (1)

Additional references from the underlying research that informed this benchmark.

Preview of McIntyre, S., Stol, J., Harvey, J., Nicholls, A.O., Campbell, M., Reid, A., Manning, A.D. & Lindenmayer, D. (2010). Biomass and floristic patterns in the ground layer vegetation of box-gum grassy eucalypt woodland in Goorooyarroo and Mulligans Flat Nature Reserves, Australian Capital Territory. Cunninghamia 11(3): 319–357.
McIntyre, S., Stol, J., Harvey, J., Nicholls, A.O., Campbell, M., Reid, A., Manning, A.D. & Lindenmayer, D. (2010). Biomass and floristic patterns in the ground layer vegetation of box-gum grassy eucalypt woodland in Goorooyarroo and Mulligans Flat Nature Reserves, Australian Capital Territory. Cunninghamia 11(3): 319–357.
Contextual Support Journal

McIntyre, S., Stol, J., Harvey, J., Nicholls, A.O., Campbell, M., Reid, A., Manning, A.D. & Lindenmayer, D. (2010). Biomass and floristic patterns in the ground layer vegetation of box-gum grassy eucalypt woodland in Goorooyarroo and Mulligans Flat Nature Reserves, Australian Capital Territory. Cunninghamia 11(3): 319–357.

View Source

Context

  • Region Australia
  • Biome Temperate Dry Woodlands & Native Grasslands
  • Land Use Agricultural Crop Production
  • Assessment Pristine Reference
  • Evidence Type HealthyOperationalRange

Lifecycle

  • Status Active
  • Version 2
  • Effective From 25 Mar 2026

Notes

Optimal range supports sustainable crop production and ecological function. [Migration] Original wider evidence range: 5 – 7 (retained OptimalRange: 5.5 – 6.5)