Use the Biochar Application Rate Conversion Calculator to determine your moisture levels and convert between units
A lab report tells you the moisture content of the sample at the moment it was analyzed — not the moisture of the material as it is delivered to you. Biochar is porous and readily takes on or loses water, and it is often stored in the open, under tarps, or outdoors where it is exposed to rain, humidity, and drying. By the time a batch is delivered and spread, its actual “as-delivered” moisture can be well above or below what the lab measured weeks or months earlier.
That difference matters, because application rates are set on a dry basis. If you load the spreader using an out-of-date moisture figure, you can easily under- or over-apply the dry tons per acre you actually intended.
How to Use the Calculator
This tool helps you turn a dry tons-per-acre recommendation into the wet tonnage and cubic yards to load into a spreader.
To get started, you’ll need to weigh a bucket of your material, add the lab dry bulk density, and enter your target rate. Weighing a bucket of the material exactly as it sits lets you capture its real, current moisture and confirm you are putting down the correct amount of biochar on a dry basis.
Biochar application rate conversion calculator
Turn a dry tons-per-acre recommendation into the wet tonnage and cubic yards to load into a spreader. Weigh a bucket of your material, add the lab dry bulk density, and enter your target rate.
Step 1
Weigh your material
Fill a known-volume bucket with biochar as it sits in the pile, at field moisture.
Calibrate this. A 5-gallon bucket usually holds a little more than 5 gallons.
Step 2
From the lab
Step 3
From the recommendation
Step 4 · optional
Your field
Add your field size to also see whole-field totals.
Result
What to load, based on your measured moisture.
Wet material
Volume to haul
How this is calculated
Wet bulk density. Net biochar weight divided by bucket volume gives density in lbs per gallon. The constant 7.48 lbs/gal per lb/ft³ converts that to a wet bulk density in lbs per cubic foot.
Moisture content. The wet density carries water that the lab-dried density does not. The difference is water weight per cubic foot, so moisture % = (wet density − dry density) / wet density × 100. This assumes the sample holds the same volume wet and dry, which attributes the full density gap to water.
Wet tons. A recommendation is set on a dry basis, but you haul wet material, so wet tons = dry rate / (% solids) × 100. Wetter material means more total tonnage for the same dry delivery.
Cubic yards. The haul volume is dry rate × 2000 / dry density / 27. Moisture changes the tonnage but not this volume, because added water raises mass and density together. The wet-basis and dry-basis paths return the same cubic yards, which is a useful check.
The constants are established: 2000 lbs/ton, 27 ft³/yd³, and 7.48 lbs/gal per lb/ft³. The moisture estimate depends on the assumption above and on the accuracy of your bucket calibration and lab density.
Spreaders are calibrated in tons per acre. Cubic yards is shown because material is often sold and hauled by volume. American Biochar Institute.
Disclaimer. This calculator is provided by the American Biochar Institute for informational purposes only and is not a substitute for professional agronomic advice. Results are estimates and will vary with your material and conditions. ABI makes no warranties as to its accuracy and assumes no liability for its use; verify all results before purchasing or applying material. Use is at your own risk.
