Humic Acid Can Improve Clay Soil

The bane of every gardener’s existence is clay soil. In addition to feeling like you are gardening in your driveway, clay soil makes ordinary tasks like watering and feeding plants a major problem. Soils with high clay content hold water and do not drain well, which causes root problems in plants. If the roots are in trouble, the whole plant will soon be in trouble. Clay particles also hold tightly to nutrient particles, which makes it more difficult for plants to take up the nutrients they need from the soil. There is a way to help your hard-packed, low organic matter clay soil: add a soil conditioner with humic acid.

Humic acid benefits plants in numerous ways. The first is that it facilitates ion exchange. Humic acid has a higher cation exchange capacity, or CEC. That means it is easier for soil nutrient particles to move within the soil, and thus to be taken in by plants. Soils treated with humic acid have much better nutrient availability. Humic acid does not directly supply the plants with nutrients, but it does make what nutrients are in the soil easier for plants to access. Humic acid also influences the pH of the soil, which affects nutrient availability. Clay soils with very low humus levels can become overly acidic, resulting in poor conditions for plant growth. Humic acid increases the buffering capacity of the soil, and allows pH to remain steadier.


An oxygen problem can technically be classified as a chemical problem, as well. Low amounts of oxygen and oxygen exchange in soil cause problems with plant roots. Plants are said to “eat” carbon dioxide and release oxygen. That is more or less true, to a point. Plants take in carbon dioxide to use in photosynthesis, the chemical reaction catalyzed by sunlight where plants make sugars from carbon dioxide and water. When plants use the sugars or starches they have made during photosynthesis, the process is called respiration. Oxygen is needed for respiration, and plants get that oxygen from the soil—taking it in through their roots. Overly clayey soils often do not have the spaces needed for oxygen in the soil. Wet, clayey soils that are completely saturated have no space for oxygen. When plants cannot take in oxygen through their roots, they suffer. Humic acid and humus helps create spaces in the soil for oxygen to be available to plant roots.

In addition to nutrient availability, nutrient uptake is an important part of plant growth. If the nutrients are there, but the plants cannot absorb them, the nutrients do not benefit the plant growth. Research has also shown that humic acid makes the cell walls of plants more receptive to nutrients and more permeable to the nutrients. This saves gardeners money, as well as encourages healthy plant growth. If you feed your plants and they cannot take in the food, you have wasted time and money, and potentially polluted the groundwater.

In addition to the many other ways that humic acid benefits plants, it does help neutralize the effects of soils high in clay content, making them more hospitable for plant growth.

Casey Coke is a Marketing Manager for Natural Environmental Systems, LLC. The company is a global supplier of humic acid and other organic soil conditioners


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