Soil Amendment Calculator

Lime raises soil pH and sulfur lowers it, so they address opposite problems -- you only need one or the other depending on whether your Target Soil pH is above or below your Current Soil pH. This calculator checks that direction once and recommends only the amendment that moves pH the way you actually want, leaving the other at zero.

Clay soils hold more negatively charged particles that buffer against pH change, meaning it takes more amendment to shift clay's pH by the same amount compared to sandy soil, which has much lower buffering capacity. This calculator's lime and sulfur rates scale up for clay and down for sand to reflect that real difference in soil chemistry.

Lime and sulfur target pH specifically, which this calculator treats as a separate problem from organic matter content -- Organic Matter % only drives Compost Needed, which is calculated independently to close the gap between your current organic matter reading and a 5% target. In real soil chemistry organic matter can have a mild pH-buffering effect too, but this calculator doesn't model that interaction.

Fertilizer here is a flat general-purpose baseline rate -- 2 lbs of 10-10-10 per 100 sq ft -- rather than a rate derived from your specific pH or nutrient levels. A true nutrient-specific fertilizer recommendation requires a full soil test reporting phosphorus, potassium, and other nutrient levels, not just pH and organic matter.

These are planning-level estimates using standard rule-of-thumb rates (lbs of lime or sulfur per 100 sq ft per pH unit, scaled by soil type), not a lab-calculated recommendation specific to your soil's actual buffering capacity. For an application rate you can rely on precisely, use the lime or sulfur recommendation from a soil testing lab, which accounts for your soil's specific chemistry more accurately than a pH reading alone.