gen-define-soil-ph-and-amendments-and-give-one-short-worked-exam-7c3b

Define soil pH and amendments and give one short worked example.

# Soil pH and Amendments ## Definitions **Soil pH**: A measure of the acidity or alkalinity of soil on a scale of 0-14, where: - pH < 7 = acidic - pH = 7 = neutral - pH > 7 = alkaline (basic) Soil pH affects nutrient availability and plant growth. **Soil Amendments**: Materials added to soil to adjust its pH to optimal levels for plant growth. Common amendments include: - **Lime** (raises pH) - for acidic soils - **Sulfur** (lowers pH) - for alkaline soils --- ## Worked Example **Problem**: A garden has soil with pH 5.0 (too acidic). You want to raise it to pH 6.5 for growing vegetables. The garden area is 100 m². How much lime is needed? **Solution**: - pH change needed: 6.5 - 5.0 = 1.5 units - Rule of thumb: ~200 g of lime per m² raises pH by 1 unit (for sandy loam) - Amount needed: 1.5 × 200 g/m² = 300 g/m² - Total lime required: 300 g/m² × 100 m² = **30,000 g = 30 kg of lime** **Application**: Spread 30 kg of agricultural lime evenly over the 100 m² garden and mix into the top 15-20 cm of soil. Retest pH after 3-6 months.