Huma: The First Name in Humates

Humic substances are carbon-rich materials formed primarily through microbial decomposition of dead plant matter, a process called humification, carried out by bacteria and fungi. These substances are found in soils, compost, peats, water, and various types of coals, which differ based on the conditions of peat formation, such as vegetation, climate, and geological processes. Because of these variations, humic substances from different sources have distinct properties and effects on plants.

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Humic substances act as plant biostimulants by inducing metabolic reprogramming, which enhances photosynthesis and energy production (ATP) for improved productivity. They also promote the development of a more branched root system, increasing the plant’s ability to absorb water and nutrients. The combined effect of more efficient photosynthesis and nutrient uptake boosts overall plant growth and performance.

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Humic substances create beneficial stress (eustress) in crops, enhancing photosynthesis, root development, and nutrient and water uptake, helping plants better withstand stress and boosting productivity. They also improve soil health by promoting root exudates that stimulate microbial activity, increase soil water content, and enhance soil structure. These microbes add carbon to the soil when they die, further enriching soil health. While humic substances don’t directly increase water or carbon exchange capacity, their biostimulant effects improve nutrient efficiency, reduce the need for fertilizers (like nitrogen), and promote healthier, more productive crops with less environmental impact.

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Liquid humate products, extracted from soft coal materials, typically contain 4% to 18% humic acid and can be applied both to soil and foliage. These products are versatile, offering immediate bioavailability for rapid plant response. In contrast, dry products, including micronized coal mixed with potassium hydroxide, are primarily for soil use and provide longer-term benefits over multiple growing seasons. The smaller the particle size, the higher the bioavailability. Choosing between liquid or dry products depends on whether you need fast results or sustained, long-term soil improvement.

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Humic substances are divided into three fractions: humic acids, fulvic acids, and the humate fraction. The key difference between them lies in their solubility in water. Humic acids are soluble in alkaline solutions but insoluble in acidic conditions, while fulvic acids are soluble across all pH levels. The humate fraction is insoluble and remains behind during extraction.

Both humic and fulvic acids consist of complex molecules made of long carbon chains (aliphatic) and ring structures (aromatic), with oxygen-containing functional groups (e.g., carboxylic or phenolic groups) that make them soluble in water. The main difference is that fulvic acids have more of these functional groups, allowing them to stay dissolved in water, while humic acids have fewer, causing them to precipitate in acidic conditions.

While humic molecules are often considered larger than fulvic molecules, their molecular sizes (measured in Daltons) overlap, with fulvic acids typically containing more oxygen and humic acids having higher carbon content.

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The effect of pH on humic substances depends on the application. In soil, pH can influence humic molecule behavior, especially in calcareous soils with high calcium and magnesium, which can bind to humic acids. However, plants maintain a pH of around 5.5 in the rhizosphere (the soil around the roots), meaning that once humic substances reach this area, pH has little impact on their effectiveness.

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Yes, soil type can affect the performance of humates. A USDA study found that in dry years with low rainfall, humic substances improved productivity across different soil types. However, in wetter years, the benefits were more noticeable in poorly-drained soils. Humic substances generally act as a form of “insurance,” boosting plant resilience to stress. For example, treated corn withstood a windstorm better than untreated plants, demonstrating their ability to improve plant strength and stress tolerance.

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Humic substances can stabilize nitrogen by binding to ammonium and nitrate. At a pH of 7-9, the negative charges in humic acids (from carboxylic and phenolic groups) can bind to ammonium ions. Nitrate can also bind through divalent cations. However, urea, being neutral, cannot be bound by humic substances. This ability helps improve nitrogen retention and slow-release in soils.

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How often you need to apply humates depends on your goals. For immediate results, liquid applications (via foliar or soil) can be done several times throughout the year. For longer-term effects, solid applications to the soil are recommended, as they can last 2-3 years. The exact duration of effects is still being studied.

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Even if your soil has high organic matter, humates can still help by reducing plant stress. However, for better results, it’s recommended to use foliar applications rather than soil applications. In soils with high organic matter, humic substances can bind together and become less effective in the soil. Foliar application ensures better uptake and results.

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Humic acid can enhance soil carbon content by stimulating plant growth and microbial activity. Humic substances promote more root exudates and fine roots, which, along with microbial decomposition, contribute carbon to the soil. When combined with manure, it’s important to manage the carbon-to-nitrogen ratio carefully. If the ratio is too low, microbes may deplete the soil’s carbon. Using humic substances helps ensure a more reliable increase in soil carbon, especially with proper tillage practices.

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There are no long-term downsides to using humates. They offer only benefits, including enhancing plant stress resistance, promoting root growth and microbial activity, and contributing to carbon sequestration in the soil. Overall, humic substances improve soil health and plant productivity without negative effects.

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