Broadcast fertilizers

Top-dressing with solid granules (less commonly powders) is the primary method of supplying plants with essential nutrients, including both micro- and macro-nutrients. It is this process that builds a stable nutrient base in the soil, supporting proper growth, development and yield. Properly selected and applied fertilisers allow plants to reach their full potential, whilst deficiencies can stunt their growth, reduce yields and even increase susceptibility to disease.

Types of granular fertilisers

Top-dressing fertilisers are most commonly classified according to their chemical composition and the type of nutrients they provide.

• Nitrogen fertilisers – nitrogen is a key building block for plants. As a component of proteins, nucleic acids and chlorophyll, it is a vital element of plant metabolism. The most commonly used nitrogen fertilisers are urea and ammonium nitrate.
• Phosphorus fertilisers – phosphorus is an element essential for proper plant development, as it influences cellular energy processes, root system development, as well as flowering and fruiting. The best-known phosphorus fertiliser is superphosphate.
• Potassium fertilisers – potassium is an important regulator of plant water management and increases their resistance to biotic and abiotic stresses. Potassium is supplied to plants in the form of salts (chloride, sulphate).
• NPK compound fertilisers – mixtures containing the macronutrients nitrogen (N), phosphorus (P) and potassium (K) in various proportions are the most versatile.
• Micronutrient fertilisers – supply elements essential to plants in small quantities for basic metabolic and vital processes. Fertilisers containing boron (B), chlorine (Cl), zinc (Zn), cobalt (Co), manganese (Mn), copper (Cu), molybdenum (Mo) and iron (Fe) are available on the market.

Advantages of using granular fertilisers

Granular fertilisers have several distinct advantages, making them one of the most commonly chosen forms of fertilisation in agriculture.

• Easy to use, simple to apply – the granules can be spread directly onto the soil without the need for specialist equipment. There is no need to dissolve the fertiliser beforehand or prepare a spray solution; the granules gradually dissolve when exposed to moisture, releasing nutrients into the soil where they become available for uptake by the root system. There is no need to worry whether the product will reach the plant and be absorbed, or whether spray droplets will run off the leaves, as is the case with foliar feeding.
• Prolonged action – nutrients from granular fertilisers are released gradually from the dissolving granules, ensuring plants receive a steady supply of nutrients over a longer period and reducing the risk of over-fertilisation.
• Ensuring the right concentration of nutrients in the soil – this is crucial when the soil is deficient in minerals and its natural reserves are unable to meet the plants’ full nutritional requirements.
• Versatility – suitable for most crops, including field crops, fruit trees, vegetables and garden plants.
• The ability to precisely adjust the composition – single-component and multi-component fertilisers are available, allowing fertilisation to be tailored to soil analysis results and plant needs.

Trends in modern fertiliser use

Despite their many advantages, the use of granular fertilisers also carries several significant environmental risks that modern agriculture must address. Applying granular fertilisers directly to the soil can lead to the risk of over-fertilisation if the fertiliser dose is incorrectly selected and the plants are unable to utilise all the nutrients supplied. In such cases, the granules may remain in the soil and contaminate it, or even lead to its degradation. The mineral compounds contained in fertilisers can leach into groundwater and subsequently enter water bodies, where they contribute to eutrophication.

This is why there is a move towards more precise fertilisation methods, which supply plants with nutrients only when they actually need them. The use of liquid foliar fertilisers can be a good complement to traditional fertilisation practices. They allow for targeted treatments tailored both to a specific crop and to its current stage of development, in line with the principles of precision agriculture. However, surface and soil fertilisation remains the fundamental and most effective method of plant nutrition, as it enriches the soil with nutrients and enables these to be supplied to crops in large quantities and in an easily absorbable form.

PCC Group products in granular fertilisers

In loose-form preparations (granular and crystalline), such as granular fertilisers, the main role of surfactants is to protect them against crystallisation and caking. Anti-caking agents are used to prevent fertiliser granules from clumping together. The PCC Group’s portfolio includes many products that can fulfil this role in loose preparations. These include members of the ROKAcet group, i.e. ethoxylated fatty acids, from the S series (stearic acid derivatives): ROKAcet S7 and S24, and the O series series (oleic acid derivatives): ROKAcet O7. Products based on tallow amine from the ROKAmin SR series (SR5, SR11, SR15) and ethoxylated fatty amines from the ROKAmin K series (K5, K15) can also serve as anti-caking agents.