Reference
Soil types
Soil texture and pH are the two axes that decide what grows easily where you garden. The four texture types (clay, sandy, silt, loam) and two pH bands (alkaline, acidic) cover almost every situation a home gardener needs to think about.
By texture
4 types-
Clay
pH 5.5 to 7.5Fine particles, slow drainage, high nutrient retention. Cracks when dry, sticky when wet. Holds water well but waterlogs roots and cracks tap-rooted vegetables.
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Sandy
pH 5.0 to 6.5Coarse particles, fast drainage, low nutrient retention. Warms fast in spring, dries out fast in summer. Easy to work but needs constant feeding.
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Loam
pH 6.0 to 7.0The reference soil. Mix of sand, silt, and clay; balanced drainage and water retention. Most crops do well in loam without amendment.
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Silt
pH 6.0 to 7.5Medium-fine particles, good moisture retention, easily compacted by foot traffic. Common near rivers. Fertile and productive when handled gently.
By pH
2 types-
Alkaline (high pH)
pH 7.5 to 8.5Soil pH above 7.5. Iron, manganese, and phosphorus become unavailable. Common in arid regions and over limestone bedrock. Hardest crops are blueberries, azaleas, and pin oaks.
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Acidic (low pH)
pH 4.5 to 6.0Soil pH below 6.0. Calcium, magnesium, and phosphorus become limited; aluminum can become toxic to roots. Common in the Pacific Northwest, the Southeast, and pine-forest regions.