Humic acids are organic compounds found in soils, derived from decomposing organic matter. They are part of a larger group of substances known as fulvic and humic acids. These acids play a crucial role in the formation and structure of agricultural soils, as well as in soil fertility. Here are a few key points about them:

1. Origin : Humic acids are derived from the decomposition of organic matter such as plant debris, dead roots, crop residues and other organic matter in the soil.
2. Composition: They are made up of various functional groups, such as fulvic acids and humic acids. These compounds contain carboxylic acids, phenolics and other functional groups, giving them complex and diverse properties.
3. Role in soil fertility : Humic acids improve soil structure by promoting the formation of soil aggregates. They also contribute to water and nutrient retention, helping to create an environment conducive to plant growth.
4. Interactions with nutrients : Humic acids have the ability to form complexes with metal ions, facilitating nutrient uptake by plants. They act as a means of storing and slowly releasing nutrients into the soil.
5. Effects on soil structure : By promoting the formation of an aggregated structure, humic acids improve soil permeability, enabling better circulation of air and water. This helps to reduce soil erosion and promote plant root development.
6. Influence on water retention : Humic acids increase the soil's capacity to retain water, which can be particularly beneficial in drought-prone regions.

In summary, humic acids are important components of soil organic matter, playing an essential role in soil fertility and structure. Understanding them is crucial to optimizing farming practices and maximizing crop productivity.

Fulvic acids are organic compounds belonging to the broader group of humic acids. They are formed by the partial decomposition of organic matter such as plant residues, plant debris and soil organisms. Here are some key characteristics of fulvic acids:

1. Chemical composition : Fulvic acids are made up of small organic molecules, smaller than those of humic acids. They contain various functional groups such as carboxylic acids, phenolics and quinones, giving them complex properties.
2. Solubility : An important characteristic of fulvic acids is their solubility in water. This property makes them mobile in the soil, facilitating their transport and interaction with plant roots.
3. Color : Fulvic acids can impart a yellow to dark brown color to the solution in which they are present. This color is often observed in drainage water or soil organic matter extracts.
4. Role in nutrient chelation : Fulvic acids have the ability to form complexes with metal ions, a process known as chelation. This property helps plants to absorb nutrients, making them more available in the soil.
5. Improving soil structure : Like humic acids, fulvic acids help improve soil structure by promoting the formation of aggregates. This increases soil porosity, facilitating air and water circulation.
6. Biological activity : Fulvic acids can stimulate microbial activity in the soil. They promote the growth of beneficial micro-organisms, contributing to the decomposition of organic matter and the release of nutrients.
7. Water retention : By improving the soil's ability to retain water, fulvic acids help maintain an optimal environment for plant growth, especially in drought conditions.

In summary, fulvic acids are essential components of soil organic matter, providing a variety of benefits such as improving soil structure, chelating nutrients and stimulating biological activity. Understanding them is crucial to optimizing agricultural practices and soil management.

ETH, or Total Humic Extract, is a fraction of the humic compounds present in fertilizers or soil improvers. Humic compounds include humic and fulvic acids, which are products of the decomposition of organic matter in the soil. ETH is often extracted from organic matter such as compost, manure or other organic soil sources. The aim of adding ETH to fertilizers is to improve soil quality and benefit plants. Here are just some of the properties and benefits associated with using ETH in fertilizers:

1. Improving soil structure : ETH contributes to the formation of soil aggregates, improving overall soil structure. Better structure promotes water retention and soil permeability, and facilitates plant root growth.
2. Soil fertility : The humic acids contained in ETH can form complexes with nutrients, helping to gradually release nutrients into the soil. This promotes better availability of nutrients to plants, contributing to soil fertility.
3. Nutrient chelation : The fulvic acids present in ETH can chelate metal ions, improving nutrient uptake by plants. Chelation makes nutrients more soluble and available to roots.
4. Stimulation of microbial activity : ETH can promote microbial activity in the soil. Soil micro-organisms play a crucial role in decomposing organic matter and releasing nutrients.
5. Leaching reduction : By improving nutrient retention in the soil, ETH helps to reduce leaching, i.e. the loss of nutrients through leaching by water.

It is important to note that the quality of ETH can vary depending on the source of organic matter used for extraction. Commercial products can be formulated to contain specific levels of humic acids to meet the needs of specific crops. The use of fertilizers containing ETH is a common practice to improve soil fertility and promote plant growth, particularly in conditions where soil organic matter is limited.