Humic Acid for Soil: What It Is and How It Works

Humic acid is a major component of humic substances, the stable organic matter in soil and in deposits such as leonardite. Used as a soil conditioner, it improves soil structure, increases nutrient availability and water retention, and supports soil biology. It is not a fertiliser and does not replace one; it improves how the soil holds and delivers nutrients.

What is humic acid?

Humic substances are the stable, dark organic compounds that remain after organic matter has broken down. They are grouped into humic acid, fulvic acid, and humin. As a commercial soil input, humic acid is usually extracted from leonardite, a soft, highly oxidised form of lignite that is rich in humic substances. It is sold as granules, powder, or liquid and applied to soil to improve its physical, chemical, and biological condition.

What humic acid does for soil

• Soil structure and aeration: helps bind soil particles into stable aggregates, improving tilth, root penetration, and drainage.
• Nutrient availability: raises cation exchange capacity so the soil holds and exchanges more nutrients, reducing leaching losses.
• Chelation: binds and gradually releases nutrients and can help free up locked soil nutrients.
• Water retention: improves the soil's ability to hold moisture, useful on sandy or fast-draining soils.
• Microbial support: provides a favourable environment for beneficial soil microbes.

Humic acid versus fertiliser, and versus compost

Humic acid is a soil conditioner, not a fertiliser: it improves how soil delivers nutrients rather than supplying significant NPK itself, so it works alongside a fertiliser program. Compared with compost, a concentrated leonardite humic acid delivers humic substances at a known concentration in a small, easy-to-apply dose. For detail, see soil enhancer vs fertiliser and SoilBoost EA vs compost and humic products.

How to use humic acid

Application depends on the product, crop, and method (broadcast, fertigation, foliar, or per tree). As a small-scale guide, SoilBoost EA is used at about 20 to 50 g per pot for ornamentals and 50 g per square metre for vegetable beds. For plantation-scale rates by crop and method, use the SoilBoost EA application-rate calculator.

Pertanyaan yang Sering Diajukan

What is humic acid?
A major fraction of humic substances, usually extracted from leonardite, used to improve soil structure and nutrient availability.

What does humic acid do for soil?
It improves structure and aeration, raises cation exchange capacity and nutrient availability, retains water, chelates nutrients, and supports soil microbes.

Is humic acid a fertiliser?
No. It is a soil conditioner that improves how soil holds and delivers nutrients, complementing rather than replacing fertiliser.

What is SoilBoost EA?
Chemiseed's leonardite-derived humic acid soil conditioner, 60.6 percent humic acid (CDFA method), made in Malaysia.

Related reading

• How Humic Acid Works in Agriculture
• Pupuk Perbaikan Tanah Berbahan Asam Humat untuk Tanah Perkebunan yang Terdegradasi
• How SoilBoost EA Improves Soil Health and Crop Yields
• Maximise SoilBoost EA: Practical Application Tips for Plantation Managers

Note: 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, CDFA method) are from product testing. Last reviewed May 2026.