Choose one outcome to measure (pH, CEC or moisture)
Write down the specific soil constraint before selecting a biochar batch. In Lampung and across Sumatra, upland agricultural soils are frequently weathered, acidic Ultisols characterized by low pH (often 4.0 to 5.2), high exchangeable aluminum (Al3+), low cation exchange capacity (CEC / KTK) and rapid nutrient leaching during heavy tropical rainfall. The USDA Climate Hubs guide recommends matching biochar properties directly to the soil amendment goal.
Select one primary outcome and define how you will measure it across all plots. For a soil moisture trial, use the same sampling depth and interval in every plot. For an agronomic trial on maize, cassava or horticultural crops, record crop variety, planting date, fertilizer baseline and harvest weight.
Check the material and the soil baseline
Request the feedstock name, batch identifier, moisture basis and laboratory report. Compare the tested sample with the delivered lot. Record the laboratory, date and method rather than copying a number without context.
Discuss soil pH, electrical conductivity, texture and the intended crop with your agronomist or laboratory. Ask which material properties and contaminant tests the intended use requires. A supplier photo cannot substitute for sample results. The corn cob biochar guide includes a buyer checklist.
Design a comparison you can interpret
Include an untreated control and replicate each treatment across the field. Randomise plot positions where practical. Keep seed, fertiliser, irrigation and harvest procedures consistent. Record changes that could explain a difference between plots.
If you test biochar mixed with compost, include a compost-only treatment. Otherwise, a difference cannot be attributed to biochar alone. Record actual masses and moisture bases for both components. This is a suggested trial design, not a report of an ENVIID field experiment.
Convert a trial rate into material mass
One hectare is 10,000 m². Therefore 1 tonne per hectare equals 0.1 kg/m², or 100 g/m². For an illustrative rate of 2 t/ha on a 10 m² plot, the dry material requirement is 2 × 1,000 / 10,000 × 10 = 2 kg.
If the delivered material contains 20% water by mass, 2 kg of dry material requires 2 / (1 − 0.20) = 2.5 kg as received. These numbers demonstrate unit conversion. Select a trial rate using the material test, soil assessment and agronomic advice.
Measure results and delivered costs
Record the same outcome for every plot. Keep individual plot results so you can examine variability. Compare treatment and control together with weather, irrigation and input records. A single photograph or one better plant cannot establish a field-wide benefit.
Record material, transport, handling and application costs separately. Express costs on the same dry-mass basis used in the trial. If the treatment meets your goal, repeat under the conditions relevant to a larger application before assuming the outcome will transfer.
Separate agronomic results from carbon accounting
The IPCC assessment explains that biochar mitigation and agronomic effects depend on biochar properties and the receiving soil. A successful crop trial does not establish a carbon credit quantity.
Link any carbon accounting to production, laboratory and application evidence. Read the digital MRV guide for those records. ENVIID is developing its Lampung pyrolysis project. To discuss a potential trial and the information available, contact the team.
Frequently asked questions
How do you convert a biochar dose in tonnes per hectare (t/ha) to grams per square metre?
Divide tonnes per hectare by 10 to get kilograms per square metre (kg/m²), or multiply by 100 to get grams per square metre (g/m²). For example, 2 t/ha of dry biochar equals 0.2 kg/m² (200 g/m²), which is 2 kg of dry biochar on a 10 m² trial plot.
Why should biochar be tested alongside a compost-only control plot?
In tropical soils, biochar is often co-applied with compost or NPK fertilizer so its pores retain nutrients and moisture. Including both an untreated control and a compost-only control allows you to isolate the specific contribution of the biochar from the nutrients supplied by the compost.
Why is biochar studied on acidic Ultisol soils in Lampung?
Weathered Ultisol soils in Lampung typically have low pH, low cation exchange capacity (CEC/KTK) and high exchangeable aluminum. Alkaline, porous biochar is investigated for its ability to buffer root-zone pH, increase nutrient retention sites and improve soil water holding capacity.