What soil amendments raise pH in acidic New Brunswick soil?

Dolomitic lime is the best and most widely recommended amendment for raising pH in New Brunswick's acidic soils, providing the dual benefit of increasing pH while also supplying magnesium, a secondary nutrient commonly deficient in Maritime soils. NB soils typically test between pH 4.5 and 6.0 — well below the 6.0-7.0 range where most lawn grasses, vegetables, and ornamental plants thrive — making liming one of the most impactful soil improvement steps any NB homeowner can take.

Dolomitic lime contains both calcium carbonate and magnesium carbonate, distinguishing it from calcitic lime, which supplies only calcium. Since NB soils are frequently low in both calcium and magnesium, dolomitic lime addresses two deficiencies with one application. It is available in powdered, granular, and pelletized forms at all NB garden centres and farm supply stores. Pelletized dolomitic lime ($8-15 per 25-pound bag) is the easiest for homeowners to apply because it flows smoothly through broadcast spreaders without creating the dust clouds associated with powdered lime. One 25-pound bag covers approximately 500-1,000 square feet depending on soil test recommendations.

Application rates depend on your current pH, target pH, and soil type, which is why a soil test ($30-60 through NB Department of Agriculture or private labs) is essential before liming. As a general guideline, raising pH by one full point (for example, from 5.0 to 6.0) requires approximately 50-75 pounds of lime per 1,000 square feet on sandy soils, 75-100 pounds on loamy soils, and 100-150 pounds on clay-heavy soils like those around Fredericton. Clay requires more lime because it has greater buffering capacity — it resists pH change more stubbornly than lighter soils. Apply no more than 50 pounds per 1,000 square feet at one time; if your soil needs more, split the application between fall and spring.

Wood ash is a fast-acting natural alternative that raises pH quickly while supplying potassium and trace minerals. It is roughly twice as effective as lime pound for pound, so use it sparingly — 10-15 pounds per 1,000 square feet maximum. Many NB homeowners with wood stoves have abundant ash available, but over-application can raise pH too high and create potassium toxicity. Never use ash from treated wood, coloured paper, or charcoal briquettes. Bone meal is another pH-raising amendment that also supplies phosphorus and calcium, though it works more slowly than lime.

Apply lime in fall (September-November) for best results, as winter freeze-thaw cycles help work the lime into the soil profile before the spring growing season. Fall application also avoids the risk of lime interfering with spring fertilizer applications. Retest your soil every 3-4 years and reapply as needed — NB's heavy rainfall continually leaches calcium from the soil, gradually re-acidifying it over time. Regular liming is not a one-time fix but an ongoing maintenance practice for productive NB landscapes.

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