Soil pH
/sɔɪl piˈeɪtʃ/
Definition
Soil ph measures how acidic, neutral, or alkaline soil is, based on the concentration of hydrogen ions in the soil solution. In horticulture, it is a chemical condition of the root zone that affects how available nutrients such as iron, phosphorus, and manganese are to plants. The pH scale runs from 0-14, with 7 as neutral; lower values are acidic and higher values are alkaline.
Practical Relevance
- Nutrient availability: Soil ph strongly affects how easily roots take up minerals. Iron, manganese, and phosphorus are especially sensitive, so unsuitable levels can cause deficiency symptoms even when nutrients are present in the ground.
- Plant preferences: Different plants grow best in different ranges. Blueberries and azaleas prefer acidic conditions, while many vegetables and lawn grasses perform best in slightly acidic to near-neutral soil ph.
- Microbial activity: Bacteria and fungi in the root zone respond to soil ph. This matters because microbes help break down organic matter and release nutrients into forms plants can absorb.
- Management choices: Gardeners use soil ph test results to guide amendments such as lime to raise pH or sulfur to lower it. Adjustments are usually gradual, because texture, organic matter, and irrigation water influence how stable the change will be.
Related Terms
pH
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Soil amendment
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Leaching
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