Example Data Table
| Scenario | Area | Depth | Initial Level | Target Level | Dry Biomass | Tissue Level | Expected Use |
|---|---|---|---|---|---|---|---|
| Small raised garden border | 20 m² | 15 cm | 180 mg/kg | 90 mg/kg | 35 kg | 110 mg/kg | Screen a plant removal plan. |
| Urban vegetable plot buffer | 50 m² | 20 cm | 250 mg/kg | 100 mg/kg | 80 kg | 120 mg/kg | Compare harvest cycles. |
| Mixed planting strip | 75 m² | 25 cm | 320 mg/kg | 150 mg/kg | 120 kg | 160 mg/kg | Add excavation replacement. |
Formula Used
Soil volume: area × depth.
Soil mass: soil volume × bulk density × 1000.
Initial load: soil mass × initial concentration.
Target load: soil mass × target concentration.
Plant removal per harvest: dry biomass × plant tissue concentration × harvest recovery.
Final load: load after plant harvests − excavated load + replacement soil load.
Final concentration: final load ÷ soil mass.
Harvests to target: safety adjusted bioavailable excess ÷ removal per harvest.
How to Use This Calculator
- Enter the garden area and treatment depth.
- Add bulk density, or enter a known soil mass.
- Enter initial and target metal concentrations.
- Add expected dry biomass and plant tissue metal level.
- Set harvest recovery, harvests per year, and safety factor.
- Add soil replacement values when excavation is part of the plan.
- Press calculate to view the result above the form.
- Use CSV or PDF buttons to save the report.
Why Soil Metal Removal Matters
Metals can stay in garden soil for many years. Lead, cadmium, zinc, copper, and nickel may come from paint, traffic, ash, old pipes, compost, or industrial dust. Some metals are plant nutrients at low levels. They can become harmful at high levels. A careful estimate helps you compare cleanup choices before you dig, plant, or haul soil away.
What This Calculator Estimates
This calculator uses soil mass, metal concentration, plant dry biomass, tissue concentration, and harvest recovery. It estimates the metal load in milligrams. It also estimates how much metal a crop can remove per harvest. The tool then shows residual concentration, removal percent, expected harvests, and years needed to approach a target level. These results are planning values. They are not a lab report.
Using Plant Uptake Wisely
Phytoextraction works when a plant grows well and stores metal in harvestable tissue. Dry biomass matters. Tissue concentration matters too. A large crop with low tissue concentration may remove less metal than a small hyperaccumulator. Repeated harvests are usually needed. Soil pH, organic matter, moisture, and root depth can change uptake. Test plots are useful. They show whether the plant performs in your actual garden.
Safe Garden Decisions
Do not eat plants grown mainly for metal removal. Treat harvested biomass as contaminated material. Follow local disposal rules. Use raised beds with clean soil for food crops when risk is uncertain. Mulch bare soil. Wash tools. Reduce dust. Keep children away from untreated areas. If test values are high, ask an extension office or qualified soil professional for site guidance.
Choosing Better Inputs
Measure depth in the zone you plan to treat. Use dry biomass, not fresh weight. Use a plant tissue test when possible. If you only have a rough uptake value, raise the safety factor. Conservative inputs help prevent cleanup plans that look optimistic later.
Limits of the Method
The formula assumes an even metal concentration through the selected depth. Real soil is mixed, layered, and variable. Lab sampling can change the estimate greatly. Plant removal also slows when available metal declines. The safety factor adds caution, but it cannot remove uncertainty. Use this calculator to screen options. Then confirm progress with repeat soil testing.
FAQs
What does metal removal from soil mean?
It means reducing the metal load in soil. This can happen through plant uptake, soil replacement, washing, or careful removal of contaminated material.
Can this calculator replace soil testing?
No. It supports planning only. Soil testing is still needed to confirm actual metal levels, risk, and cleanup progress.
Why does the calculator use dry biomass?
Plant tissue metal concentration is usually reported on a dry weight basis. Dry biomass gives a cleaner estimate of removed metal.
Can harvested plants be eaten?
No. Plants used for metal removal should not be eaten. Treat them as potentially contaminated material and follow local disposal rules.
What is harvest recovery?
Harvest recovery is the percent of metal-rich plant material actually collected. Losses can happen during cutting, handling, drying, and transport.
What is the safety factor?
The safety factor adds caution. It increases the estimated removal need to cover field variation, uneven soil mixing, and uncertain plant uptake.
Why include bioavailable fraction?
Only part of the metal may be available for plant uptake. This setting helps estimate the practical removal workload for phytoextraction planning.
What should I do if the target is not met?
Increase harvest cycles, improve biomass, choose better plants, replace some soil, or consult a qualified soil professional for safer options.