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Calcimator

Earthworm Count Calculator

Estimate earthworm population density per acre from field sample counts with moisture corrections.

Inputs

Results

Worms per ft²

12

Worms per acre522,720
Worm biomass (lb/ac)1,152.6
Soil processed (tons/ac/yr)24
Health score (0-100)50
Biomass G Per (m²)129.17
RatingModerate
Sampling CVModerate
How to Use This Calculator
  1. Dig a 12-inch cube of soil and count all earthworms found.
  2. Enter your earthworm count and the soil moisture percentage at sampling.
  3. Input the soil temperature at the time of sampling.
  4. Review the Earthworms per Cubic Foot and the Soil Health Rating.
  5. Use the Recommended Count Threshold to determine if biological activity is adequate for your crop system.

How the result changes with Sample area (ft²)

Sample area (ft²)Worms per ft²
1.0911
3.563.4
6.541.8
9.011.3

What each input means

Worms found per sample
Average number of earthworms counted in each sample pit or extraction.
Sample area (ft²)
Area of each sample (standard: 1 ft² = 12 in × 12 in).
Number of samples taken
More samples (5-10+) improve estimate reliability.
Soil moisture condition
1=Very Dry, 2=Dry, 3=Moist (ideal), 4=Wet, 5=Saturated. Dry soils undercount worms.

What each result means

Worms per ft²
Corrected earthworm density per square foot.
Worms per acre
Estimated total earthworm population per acre.
Worm biomass (lb/ac)
Estimated earthworm biomass assuming ~1 g average worm weight.
Soil processed (tons/ac/yr)
Estimated tons of soil cycled through earthworm casts per year.
Health score (0-100)
Earthworm population health rating from 0 (degraded) to 100 (excellent).

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Worms found per sample = 12, Sample area (ft²) = 1, Number of samples taken = 5, Soil moisture condition = 3 = 4 input(s) provided
  2. Calculate Worms per ft²
    Worms per ft² = (wormsPerSample / sampleArea) * moistureFactor
    12 = 12
  3. Calculate Worms per acre
    Worms per acre = wormsPerFt2 * 43560
    522720 = 522720
  4. Calculate Worm biomass
    Worm biomass = wormsPerAcre * 0.001 * 2.205
    1152.6 = 1152.6

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