Production and application of humic fertilizers based on leonardite in Ukraine (Chernihiv)

The importance of organic fertilizers for soil fertility

The fertility of sod-podzolic soils is primarily determined by their humus content. Successful farming in such conditions requires an annual application of at least 10 tons of organic fertilizer per hectare of soil.

It's impossible to meet agricultural demand for organic fertilizers with manure alone. Furthermore, its humic substance and nitrogen content are inferior to some other organic materials. Therefore, in Ukraine, and particularly in the Chernihiv region, leonardite is the most promising source of raw material for organic fertilizers and occupies an important place in their balance.

It has been established that humic substances and nitrogen in the feedstock are immobile and are slowly and incompletely absorbed by plants. To address this issue, various methods for activating organic matter are used.

Scientific basis and methods of activation

An effective way to activate the organic matter in leonardite is by treating it with alkalis (ammonium hydroxide or gaseous ammonia). This results in the formation of water-soluble ammonium humates and other compounds, and the activation of a significant amount of organic nitrogen. This reveals a very important property of humic substances—their stimulating effect. In the presence of such substances, plants utilize not only the nitrogen absorbed from the ammonia and the activated nitrogen from organic compounds, but also the mineral reserves of the soil.

Research conducted by scientists at specialized agricultural research institutions in Chernihiv, Ukraine, has resulted in the development of an advanced method for producing and applying humic fertilizers based on leonardite. The fundamental principle of their production is the maximum activation of humic substances and nitrogen through ammoniaization with ammonia or ammonia water directly during the application of fertilizers to the soil.

Unlike traditional mixtures, these fertilizers are prepared without the lengthy composting of ammoniated leonardite. With prolonged aging (more than 1–1.5 months), the mobility of humates and activated organic nitrogen begins to decline. Rapid microbial growth leads to nitrate accumulation and subsequent denitrification processes, which reduces the fertilizer's effectiveness. However, under autumn-winter conditions, leonardite treated with ammonia can be aged until spring sowing.

Seasonal cooking features

Depending on the time of year and agricultural objectives, the nature of the work on preparing and using humic fertilizers varies:

• Spring-summer period: Preparation is combined with the soil application process for the current year's sowing. Fertilizers prepared for future use (not combined application) should be stored for no more than 1–1.5 months.
• Autumn period: Fertilizers can be prepared either for simultaneous application under the sowing of next year’s crops (which is the most promising), or in reserve for application in the spring.
• Winter period: Fertilizers are prepared only for stockpiling directly in field areas or at leonardite mining and storage sites.

Mineral components and raw material requirements

In addition to the raw material itself and ammonia water nitrogen, phosphorus and potassium mineral components can be added to the composition of humic fertilizers based on leonardite.

The most practical method is to use phosphate rock. To increase phosphorus mobility, it must be pre-composted with leonardite before ammoniation (calcium phosphates are decomposed by free organic acids). Adding potassium fertilizers to this mixture further enhances phosphate decomposition, as potassium ions react with hydrogen from the active groups to form free mineral acids. When the mixture is ammoniated, this process is stopped, as the active groups are neutralized.

Requirements for leonardite for fertilizer production:

• The raw material must be crumbly.
• The content of particles up to 1 cm in size is at least 60–70%.
• Absence of solid inclusions larger than 5 cm.
• Optimum humidity is within 50–60%.

The degree of ammonia nitrogen saturation in fertilizers is determined by the absorption capacity of the raw material. Fertilizers prepared for stockpiling are saturated with ammonia nitrogen to 1.2–1.4%. When applied and incorporated into the soil simultaneously, the concentration can be increased to 2%.

Mechanization of the production process

The main process—ammonization of leonardite—is carried out by counter-mixing streams of crushed raw materials and sprayed ammonia water in a closed chamber. A specialized unit for producing concentrated humic fertilizers is used for this purpose.

The operating principle of the complex:

1. The unit doses and mixes leonardite chips with ammonia water.
2. The raw material is fed by a conveyor into the enrichment chamber in the form of a suspended flow.
3. Ammonia water is supplied under pressure through sprayers.
4. The processed mixture is directed to the soil through a protective sleeve and immediately undergoes preliminary sealing.

The final incorporation to a depth of 10–15 cm is carried out by a following cultivator or stubble cultivator.

Application rates and efficiency

Leonardite-based humic fertilizers are highly effective and can be used for all types of agricultural crops:

The Ministry of Agrarian Policy and Food of Ukraine recommends these fertilizers for widespread use in the agro-industrial complex. Clear evidence of their high agronomic and economic efficiency is provided by the results obtained at leading farms in the Chernihiv region (specifically, in the fields of the Chernihiv, Nizhyn, and Pryluky districts).

Agro.Bio Expert Note: Building on the profound scientific research of the Chernihiv School of Agrochemistry, Agro.Bio has taken the production of humic products to a fundamentally new technological level. Today, highly concentrated liquid formulations (such as Agro.Bio Potassium Humate and Agro.Bio Totem ) completely eliminate labor-intensive, cumbersome ammoniation processes in the field. Ready-to-use biotechnological complexes, with an application rate of just 1–2 l/ha, ensure maximum mobilization of nutrients, stimulate soil microflora, and guarantee highly profitable crop production in all soil and climatic conditions in Ukraine.