Leonardite Humic Acid Soil Conditioner: Source, Composition, and How It Works

Leonardite is a soft, highly oxidised form of lignite and the richest natural source of humic acid. Chemiseed's SoilBoost EA is made from 100% leonardite ore and contains 60.6 percent humic acid (CDFA method). As a soil conditioner it improves nutrient uptake, chelates micronutrients, and builds soil structure. It is not a fertiliser and does not replace one.

What is leonardite?

Leonardite is a soft, brown, highly oxidised form of lignite (brown coal). The slow oxidation that formed it concentrated humic substances, which is why leonardite is the richest natural source of the humic and fulvic acids used in agriculture. Humic acid extracted from leonardite is far more concentrated than the humic content of compost or raw manure, so a small, consistent dose delivers a known quantity of humic substances rather than a variable one.

SoilBoost EA: source and key ingredients

Source material	100% leonardite ore (oxidised lignite)
Humic acid	60.6 percent (CDFA method)
Fulvic fraction	Present; lower molecular weight, mobile, carries micronutrients into the plant
Chelated micronutrients	Iron, zinc, and copper held in plant-available form
Sulphur	About 0.45 percent
pH	3.84 (acidic; suits neutral-to-alkaline tropical soils, applied at low rates)
Manufacturer	Chemiseed Sdn. Bhd., Subang Jaya, Malaysia

How leonardite humic acid works

Chelation. Humic and fulvic molecules form stable, water-soluble complexes with metal micronutrients such as iron, zinc, and copper, keeping them available to roots instead of precipitating in the soil.

Cation exchange capacity. The high charge density of humic acid raises the soil's effective cation exchange capacity, so it holds and exchanges more nutrient cations and loses fewer to leaching.

Nitrate-uptake signalling. Humic substances can stimulate the root plasma-membrane proton pump and nitrate transporters (such as NRT2.1 and MHA2), which is associated with improved nitrogen-uptake efficiency.

Organo-mineral complexation. Humic acid binds soil minerals into stable aggregates, improving structure, aeration, and water-holding capacity.

What the research shows

Independent research on leonardite humic acid supports these mechanisms. A 2024 study in Agronomy (MDPI; Ma et al.) reported that humic-acid application raised crop yield by about 12 percent, nitrogen-use efficiency by about 27 percent, and nitrogen uptake by about 17 percent versus an untreated control. An earlier meta-analysis (Rose et al., 2014) found that humic substances increased shoot biomass by roughly 22 percent and root biomass by roughly 21 percent on average, while noting that results vary with soil type, rate, and crop.

These figures come from the wider humic-acid literature, not from SoilBoost EA trials specifically. For SoilBoost EA's own field data, including the FPA EUP 3227 banana trial, see the Evidence Hub.

Pertanyaan yang Sering Diajukan

Is leonardite humic acid a fertiliser?
No. It is a soil conditioner. It does not supply significant NPK on its own; it improves how the soil holds and delivers nutrients, so it works alongside a fertiliser program rather than replacing it.

Why leonardite rather than another humic source?
Leonardite is the most concentrated natural source of humic substances, so it delivers a known, consistent dose in a small volume, unlike compost or manure where humic content is low and variable.

What concentration does SoilBoost EA contain?
60.6 percent humic acid by the CDFA method, derived from 100% leonardite ore.

Does the low pH harm the soil?
The product is acidic (pH 3.84) but is applied at low rates and buffered by the soil. It suits neutral-to-alkaline tropical soils. Use the application-rate calculator to size the dose for your crop and method.

Related reading

• Humic acid for soil: what it is and how it works
• Humic acid (asam humat) for tropical plantations
• SoilBoost EA vs compost and generic humic products
• Soil enhancer vs fertiliser

Note: Leonardite humic acid is a soil conditioner, not a fertiliser, pesticide, or plant protection product. Results depend on soil type, baseline organic matter, crop, and management. SoilBoost EA values (60.6 percent humic acid by CDFA method, pH 3.84) are from product testing. Last reviewed June 2026.