Urine-Enhanced Biochar Field Trial
Citation: Schmidt H-P, Pandit BH, Martinsen V, Cornelissen G, Conte P, Kammann CI (2015). Fourfold increase in pumpkin yield in response to low-dosage root zone application of urine-enhanced biochar to a fertile tropical soil. Agriculture 5(3): 723–741. https://doi.org/10.3390/agriculture5030723 (open access)
What it is: A single pumpkin field trial in Nepal. It compared compost plus urine, compost plus biochar, and compost plus urine-loaded biochar, all placed in the root zone. It’s the vault’s reference for low-dose, urine-charged biochar.
Key figures
| Figure | Value | Where | Check |
|---|---|---|---|
| Biochar | Eupatorium adenophorum (invasive shrub), flame-curtain kiln; met European Biochar Certificate premium criteria | Abstract | ✓ abstract |
| Charging | Mixed 1:1 by volume with fresh cow urine | Abstract | ✓ abstract |
| Dose and placement | 750 kg ha⁻¹ biochar dry matter, root zone, before seeding | Abstract | ✓ abstract |
| Background amendment | Cow-manure compost in every treatment | Abstract | ✓ abstract |
| Urine-biochar yield | 82.6 t ha⁻¹ pumpkin | Abstract | ✓ abstract |
| vs urine only | More than +300% | Abstract | ✓ abstract |
| vs biochar only | +85% | Abstract | ✓ abstract |
| Soil | Fertile silt loam | Abstract | ✓ abstract |
| Soak urine and biochar at least 1 hour before applying | Protocol detail used in Biochar Inoculation for Fertilizer | — | not re-checked (full text blocked to automated download) |
Use with care
- One site, one crop, one season: a strong demonstration, not an average effect. The multi-site follow-up is liquid nutrient enrichment trials.
- The authors tentatively attribute the gain to an organic coating that urine loading forms on pore surfaces. The abstract offers this as an explanation, not a measured cause.
Related: liquid nutrient enrichment trials · Biochar Inoculation for Fertilizer · Biochar Nutrients and Fertilizer Chemistry · Key Sources