Tropical vs Temperate Yields
Citation: Jeffery S, Abalos D, Prodana M, Bastos AC, van Groenigen JW, Hungate BA, Verheijen F (2017). Biochar boosts tropical but not temperate crop yields. Environmental Research Letters 12(5): 053001. https://doi.org/10.1088/1748-9326/aa67bd (open access)
What it is: A global meta-analysis that splits biochar yield effects by latitude. It’s the vault’s main evidence that yield benefits concentrate in acidic, low-fertility tropical soils.
Key figures
| Figure | Value | Where | Check |
|---|---|---|---|
| Temperate latitudes | No average effect on crop yield | Abstract | ✓ full text |
| Tropics | ~25% average yield increase | Abstract; results, fig. 1 | ✓ full text |
| Tropical mechanism | Liming and fertilization | Abstract | ✓ full text |
| Nutrient content of the char | In tropical soils, high-nutrient biochars raised yields substantially more than low-nutrient ones | Abstract | ✓ full text |
| pH gap behind the liming effect | Median biochar pH 9.0 vs median tropical soil pH 5.7 | Discussion | ✓ full text |
| Advice for temperate systems | Focus on non-yield benefits: lime and fertilizer savings, GHG control, other ecosystem services | Abstract | ✓ full text |
Use with care
- “No effect on average” in temperate soils hides variation. The authors discuss over-liming, which can tie up micronutrients, as one possible reason for yield decreases.
- Charged or enriched products are a different question; see meta-analyzes biochar fertilizers and liquid nutrient enrichment trials.
Related: meta-analyzes crop productivity · Crop Yield Effects · Soil and Agriculture · Key Sources