Soil Health Scorecard Calculator

This calculator builds a composite soil health score modeled on frameworks like Cornell's Comprehensive Assessment of Soil Health (CASH) — which scores organic matter, wet-aggregate stability, respiration, and active carbon among its measured indicators, converting each to an interpretive 0-100 rating — and NRCS soil health guidance, scoring five independent indicators on their own 0-20 point scale and summing them into a single 0-100 total. (This calculator sums five fixed indicators to a 0-100 total rather than CASH's own approach of averaging a configurable indicator set, so treat it as CASH-inspired shorthand rather than a reproduction of Cornell's official scoring engine.) Organic matter is scored on a piecewise curve with diminishing returns: points come fastest at the low end (5 per percentage point below 2%), slow to 3 per point through 2-4%, slow further to just 2 per point through 4-6%, then flatten out entirely above 6% — so the earliest gains off a depleted baseline count for the most. Aggregate stability — the percentage of soil clumps that survive wet-sieving intact — follows the same front-loaded shape, climbing fastest below 10% stable aggregates and easing to progressively smaller gains (0.3, then 0.2, then 0.15 points per percentage point) as stability improves through 80%. Soil respiration (CO2 burst) is scored against thresholds from roughly 0.2 to 1.5+ mg CO2-C per gram per day, capturing microbial activity. pH gets a symmetric penalty curve peaking at the 6.0-7.0 sweet spot where most nutrients are maximally available to plants, with points falling off toward both acidic and alkaline extremes.

Active carbon (POXC), the labile, easily-oxidized carbon pool that feeds soil microbes, is scored from under 200 mg/kg up through 1,100+. Each sub-score is capped at 20 and the five are added for the total, which then maps to a letter grade from F (under 40) to A (90+). Rather than leaving you to interpret five numbers at once, the calculator also identifies whichever indicator scored lowest relative to its own scale and surfaces a targeted, practice-specific recommendation — liming for low pH, cover crops for low organic matter, and so on — so you know where to focus first.