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Calcimator

Organic Matter Calculator

Calculate compost needed to raise soil organic matter, with estimates for water holding capacity improvement, CEC boost, and nitrogen mineralization.

Inputs

inches
acres

Results

OM Increase Needed

2%

Compost per Acre

179.9 tons

≈ 30 elephants

Total Compost1,799 tons
Water Holding Improvement1.2 in/ft
CEC Boost4 meq/100g
Annual N Mineralization100 lbs/acre
Years to Reach Target20 years
Estimated Cost$53,970.00
How to Use This Calculator
  1. Enter your current soil organic matter percentage from a recent lab test.
  2. Set your target organic matter percentage.
  3. Input annual organic inputs in tons per acre (compost, manure, crop residue).
  4. Review the Estimated Carbon Sequestration Rate and Years to Target.
  5. Use the Organic Matter Influence on CEC output to understand its effect on nutrient-holding capacity.

How the result changes with Target Organic Matter

Target Organic MatterOM Increase NeededCompost per Acre
1.5%0%0 tons
5.25%3.25%292.4 tons
9.75%7.75%697.2 tons
14%12%1,079.5 tons

What each input means

Current Organic Matter
Current soil organic matter percentage from your soil test. US cropland averages 2–5%.
Target Organic Matter
Desired organic matter level. Higher OM improves structure, water retention, and fertility.
Incorporation Depth
Depth to which compost will be incorporated. Standard plow depth is 6–8 inches.
Area
Total area to be amended in acres.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Current Organic Matter = 2, Target Organic Matter = 4, Incorporation Depth = 6, Area = 10 = 4 input(s) provided
  2. Calculate OM Increase Needed
    OM Increase Needed
    2 = 2
  3. Calculate Compost per Acre
    Compost per Acre
    179.9 = 179.9
  4. Calculate Total Compost
    Total Compost
    1799 = 1799
  5. Calculate Water Holding Improvement
    Water Holding Improvement
    1.2 = 1.2

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