Humic Acid is an amazing natural substance with a wealth of benefits for lawns. Here’s why I’m adding Humic Acid to my list of lawn treatments in Belfast.

What is Humic Acid?

Unless you are a soil scientist, a farmer, or a very keen gardener, you probably won’t have heard of Humic Acid. It doesn’t pop up in the school curriculum and it hasn’t found its way onto garden centre shelves just yet. It truly is one of Mother Nature’s best-kept secrets.

Compost is a rich source of humus, which in turn supplies the building blocks for humic acid.

The organic matter in your garden soil is known as humus. It gives the soil a lovely rich brown colour and a fabulous crumbly texture.  Some soils have more humus than others. Sandy soils for example have pitifully low proportions of humus – which is why it’s so hard to grow a lawn on sand. Unimproved clay soils also tend to be lacking in humus.

Humic acid is one of the chemical constituents of humus. It’s what’s left once the worms, beetles and soil microbes have finished breaking down all those dead leaves and roots. You can’t see it – the molecules are far too small to be visible – but you can definitely see the difference between lawns where there is plenty of Humic acid and lawns where there is not much Humic acid at all.

What does Humic Acid do?

Humic Acid is the soil science equivalent to a supermarket delivery truck. It brings plant food to the roots so that the plants can be nourished.

Picture for a moment a lovely grass plant sitting with its roots in the soil and its leaves looking up to the sky. That plant needs food and water so that it can live, grow, and be healthy. Just like us, plants need carbohydrate, protein, water and minerals to build new cells and repair damaged ones. Energy comes from the sun (photosynthesis) but the chemical constituents of a plant cell are absorbed from the soil by the roots.

These plants are actually wheat – a different type of grass, but the picture helps you to see what’s happening in the soil layer.

The roots of a grass plant are static. They’re surrounded by soil and they can’t go out foraging for food. All of the plant nutrients need to be in the soil immediately next to the roots so that they can be absorbed. (Water and nutrients enter the plant via microscopic holes in the surface of the root).

What happens if the plant uses up all of the nutrients around its roots? It finds itself sitting in a depletion zone.  (Just like us during the COVID lockdown when panic buyers had emptied the supermarket shelves.)

Humic acid binds to plant nutrients in the soil and drags them into the depletion zones around roots. Which is why it’s like a supermarket delivery truck.

What the scientists say about Humic Acid

This quote is from the Journal of Chemical Education published in 2001. It sums Humic Acid up far better than I ever could.

Humic acids are remarkable brown to black products of soil chemistry that are essential for healthy and productive soils. They are functionalized molecules that can act as photosynthesizers, retain water, bind to clays, act as plant growth stimulants and scavenge toxic pollutants. No synthetic material can match Humic Acid’s physical and chemical versatility”

Benefits of adding Humic Acid to your soil

We know that well-nourished lawns are healthier, more hardwearing and look better. Humic acid optimises lawn nutrition but it has lots of other benefits for soil health and the environment too. It’s all to do with that remarkable ability to latch onto molecules and move them around within the soil

  • Improved soil structure – helps soil become more loose and crumbly and easier for roots to grow into
  • Reduces cracking, surface water runoff and soil erosion
  • Helps to retain water
  • Darkens the soil colour and helps it to retain warmth from the sun
  • Neutralises both acidic and alkaline soils bringing the pH closer to 7 (the optimum pH for grass is around 6)
  • Optimises plants’ uptake of nutrients and water
  • Binds to soil nutrients and stops them being washed away by wet weather or irrigation
  • Makes phosphorus more accessible to plants (grass uses phosphorus to build a strong root network)
  • Supports the soil micro-organisms that are crucial for sustainable soil and plant health
  • Promotes plant growth

Soil that is prone to cracking like this during dry weather can be improved by applying Humic Acid

How to add Humic Acid to your soil

Humic Acid is a natural soil conditioner – it’s all part of nature’s cycle of life. When you mulch your borders with compost or bark mulch, you are providing soil microbes with the materials to create Humic Acid. However – I don’t recommend mulching your lawn – that won’t work at all!

Instead, Humic Acid can be added as a lawn treatment by a trained professional. It’s important to get the dose right and to apply it nice and evenly. I like to use alongside a seaweed treatment, that way I’m boosting the roots and the shoots of the plant.

Click here to learn more about the nutrients your lawn needs

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