Frequently Asked Questions

Determine your target pH from your crop specifications, obtain your soil CEC or SMP Buffer pH and Organic Matter % from a lab soil report, calculate pure CaCO3 requirement, and divide by the ENV/ECCE rating on your limestone supplier's delivery ticket.

CCE measures chemical purity only. ECCE and ENV factor in both chemical purity and particle fineness, providing the actual neutralizing capacity in field soil.

Each 1% increase in organic matter increases total soil buffering capacity, requiring approximately 15% more limestone to achieve the same target pH shift compared to low-OM mineral soils.

Click the Download CSV Matrix button in the calculator to generate an export with date stamps, field area, target pH range, OM adjustments, pure vs. adjusted tonnages, and application density rates.

No. Gypsum (CaSO 4 ·2H 2 O) is a chemically neutral salt. While it contains sulfur in sulfate form (SO 4 2- ), it dissociates without releasing hydrogen ions (H + ). Gypsum is used to add calcium and sulfur to sodic or compacted clay soils without altering soil pH. Use Elemental Sulfur to lower pH.

No. Epsom salt (MgSO 4 ·7H 2 O) is also a neutral sulfate salt and has zero acidifying effect. It supplies water-soluble magnesium and sulfur to correct deficiencies but will not alter soil pH.

Clay soils have a high Cation Exchange Capacity (CEC) and a massive internal surface area holding large reserves of basic cations (Ca 2+, Mg 2+, K + ). This creates high buffering capacity, requiring up to 3 times more acid-producing hydrogen ions to achieve the exact same pH drop compared to coarse, low-CEC sandy soils.

No. Household vinegar (acetic acid) is a weak organic acid that evaporates and degrades quickly under microbial action within 24 to 72 hours. Furthermore, applying strong concentrations of vinegar harms beneficial mycorrhizal fungi and earthworms. Use biological elemental sulfur for stable, long-term soil conditioning.

Late spring or early fall. Soil bacteria require soil temperatures above 55°F (13°C) and consistent moisture to oxidize sulfur. Late spring allows active conversion through summer. Early fall applications begin oxidizing before frost and resume early the following spring before the growing season starts.

CEC measures a soil's ability to hold onto positively charged nutrient ions (cations like Ca2+, Mg2+, K+, Na+, H+, Al3+). Higher CEC indicates greater nutrient retention capacity and pH buffering capacity.

To convert ppm (mg/kg) to meq/100g, divide the ppm value by (Equivalent Weight × 10). Equivalent weight equals atomic weight divided by the cation charge valence.

For most agricultural crops and lawn turfgrass, ideal base saturation ranges between 60% and 80%, with targets around 60-75% Calcium, 10-20% Magnesium, 3-5% Potassium, and less than 3% Sodium.

If soil pH is below about 6.2 and acidity needs correcting, use calcitic lime. If pH is already at or above target, use gypsum, which supplies calcium without raising pH. A base saturation calculator can route this automatically from your pH value.

Yes, when the compaction is caused by high magnesium and low calcium base saturation (Ca:Mg ratio below about 4:1). Gypsum replaces magnesium with calcium on the exchange complex, restoring flocculation and crumb structure over one to three seasons.

Calcium 64–75%, magnesium 10–15%, potassium 2–5%, sodium 0.5–3%, with hydrogen and other cations making up the remaining 15% or less of the CEC. The ideal Ca:Mg ratio is roughly 5:1 to 8:1.

Cation ratio effects on soil structure (flocculation vs compaction) and K:Mg antagonism are well established soil science. However, research does not consistently show that exact ratio targets outyield sufficiency-based fertilization, so the method is best used as a structural and diagnostic framework.

Gypsum will not burn plants or shift pH, but rates above about 2–3 tons per acre per season are wasteful. Split larger prescriptions across multiple years.

Take the antilog: [H+] = 10^(minus pH). A pH of 6.50 gives 10^-6.50 = 3.16 x 10^-7 mol/L, which is 0.32 umol/L or about 0.00032 mg/L as H+. The calculator reports all of these at once, plus the companion pOH and [OH-].

They are the two halves of water's self-ionisation balance at 25 degrees C, where pH + pOH = 14.00. A pH of 6.50 is a pOH of 7.50. pH describes hydrogen ion activity, pOH describes hydroxide activity, and either one determines the other.

The scale is a base-10 logarithm, so every whole unit is a tenfold change in hydrogen ion activity. Dropping from pH 7.0 to 5.5 multiplies activity about 32 times, which is why lime and sulphur are specified in tonnes per hectare rather than in pH points.

No. pH in CaCl2 or KCl usually reads 0.5 to 0.8 units lower than the same soil in water because the salt displaces hydrogen from the exchange sites, and buffer pH methods (SMP, Sikora) measure reserve acidity for lime sizing instead. Always quote the method with the number.

ESP = exchangeable sodium divided by CEC, multiplied by 100, with both values in meq/100g. Sodium at 1.8 meq/100g in a soil with a CEC of 18 gives an ESP of 10%. If the report lists sodium in mg/kg, divide by 229.9 first to reach meq/100g.

An ESP of 6% or more is treated as sodic in current guidance, the point where clay begins to disperse and surface crusting appears. An ESP at or above 15% is the US Salinity Laboratory definition of a strongly sodic, or alkali, soil where most crops fail.

ESP measures the sodium already held on a soil's exchange complex, while SAR measures the sodicity hazard of irrigation water using sodium divided by the square root of (Ca + Mg) over 2 in meq/L. SAR predicts whether ESP will rise over time; it does not replace the soil measurement.

Replace exchangeable sodium with calcium using gypsum, or lime where free carbonate is present and pH is low, then leach the displaced sodium below the root zone with adequate drainage. Re-test afterwards, and rebuild structure with organic matter and controlled traffic while the soil recovers.