The soil environment consists of a variety of physical, biological and chemical factors that affect the abundance and diversity of microbes and serve as a reservoir of water and nutrients. It is also involved in the cycling of carbon and other elements through the global ecosystem.

With most farmers in Zimbabwe having very tight rotations schedules or no rotations at all, our soil environment is deteriorating leading to unfertile lifeless soils.

Humic acid modifies the physical structure of the soil which produces the following benefits:

  1. Improves soil structure


Light Sandy Soils : humic acid increase the soils nutrient and water holding capacity by coating sand particles, preventing high water and nutrient losses while transforming unproductive soils to rich soils by way of decomposition. They hold water and nutrients in plant available forms at root zone and provide to plants as needed.

Heavy and Compact Soils: humic acid helps soil to loosen, creating looser crumbly soil which improves the penetration of nutrients, plant roots and water in the soil. It increases aeration of the soil, water retention capacity and improves soil workability.

  1. Increases water holding capacity of soil.
  2. Improves drought resistance of soil.
  3. Darkens colour of soil which helps in absorption of the sun’s energy.


Humic acid chemically changes the fixation properties of the soil. It helps to neutralize acidic and alkaline soils, regulates pH value of soils, increasing their buffering abilities and also has extremely high cation-exchange properties giving the following benefits:

  1. Improves and optimizes uptake of nutrients and water holding capacity
  2. Stimulates plant growth with its rich organic and mineral substances
  3. Helps retain water soluble inorganic fertilizers in the root zone
  4. Enhances the uptake of nitrogen by plants
  5. Reduces the availability of toxic substances in the soil.


Humic acid biologically stimulates plants and activities of micro-organisms which encourages the following benefits:

  1. Stimulates plant enzymes and increases their production.
  2. Stimulates growth and proliferation of desirable micro-organisms in soil
  3. Enhances plants natural resistance against disease and pesticides
  4. Stimulates root growth and enables better nutrient uptake
  5. Increase vitamin and mineral content of the plants
  6. Increase germination and viability of seeds


By just using fertilizers we can’t reach maximum crop yields. Maximum yields require organic matter humic acid, high cation exchange capacity and biological activity.

Soil pH affects many chemicals and biological reactions. It is an important parameter for plant nutrition – in high acidity absorption of nutrients such as nitrogen, phosphorus, potassium, sulphur & calcium diminishes and in high alkaline conditions absorption of iron, manganese, boron, copper, and zinc decreases.


Sean Price

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