Answer: The best thing you can do to improve alkaline soil is to incorporate a 4-6 inch layer of compost before each planting season. Organic matter is constantly breaking down into its smallest components, so it's important to keep adding compost each year. It provides nutrients, improves drainage in clay soils and improves water retention in sandy soils. And, it contributes to the rich environment of soil microorganisms and earthworms.
Pine needles are acidic so they can help reduce alkalinity. However, their waxy coating doesn't break down easily, so it's best to compost them first, before adding them to your soil.
Alkaline clay soils have a tendency to attract and hold sodium, which eventually impedes water penetration. Adding either sulfur or gypsum as soil amendments and watering deeply, helps leach these salts below the root zone. Follow package directions for the amount to apply for your area.
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