Soil amendment
/ˈsɔɪl əˈmɛndmənt/
Definition
Soil amendment refers to a material added to soil to change its physical or chemical properties, such as structure, drainage, water-holding capacity, pH, or nutrient availability. Unlike fertilizer, which mainly supplies nutrients, a soil amendment is defined by how it modifies the soil itself. Common examples include compost, bark, perlite, lime, and sulfur, used in garden beds, containers, and planting sites.
Practical Relevance
- Root-zone structure: Soil amendment can loosen dense clay, improve pore space, and help roots reach oxygen and water more evenly. In very sandy ground, it can increase water-holding capacity and reduce rapid drying.
- Nutrient behavior: Some types influence how nutrients move and stay in the root zone. Organic materials can support gradual nutrient release as they break down, while pH-changing materials can affect nutrient availability to plants.
- Microbial activity: Organic soil amendment often feeds beneficial soil microbes that help decompose material and cycle nutrients. Stronger microbial activity can also improve aggregation, which means soil particles bind into a more stable structure.
- Match to site conditions: Results depend on the existing soil, the plant being grown, and the material used. A soil test is useful before applying soil amendment that changes pH or adds significant nutrients.
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