Slow release fertilizers ( SLR) are those that release their nutrients in a gradual and controlled manner, better adapting to the demand of the plants and minimizing losses to the environment.
FLRs differ from conventional fertilizers, which dissolve quickly in water and release their nutrients immediately, which can cause problems such as leaching, volatilization, eutrophication or salinization.
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Slow release fertilizers are classified into three types, depending on the mechanism that regulates the release of nutrients:
Coated fertilizers: they are conventional fertilizers that come in the form of granules wrapped in a semipermeable membrane, which can be sulfur, resins, rubber, paraffins, perforated plastic, etc. The membrane breaks down due to the action of water, temperature or microorganisms, progressively releasing nutrients.
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Low-solubility fertilizers: These are fertilizers that contain nutrients in a chemical form that delays their dissolution in water, such as isobutylidene diurea, methyleneurea or urea-formaldehyde. These fertilizers are hydrolyzed by the action of microorganisms, releasing the nutrients slowly.
Fertilizers with nitrification inhibitors: these are fertilizers that contain chemical compounds that inhibit the activity of bacteria that transform ammonium into nitrite and then into nitrate, such as nitrapyrin or dimethylpyrazole phosphate. These fertilizers maintain nitrogen in the form of ammonium, which is less susceptible to loss through leaching or volatilization.
What are slow release fertilizers used for?
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Slow release fertilizers are used to nourish plants efficiently and sustainably, especially in crops that require prolonged and uniform fertilization, such as fruit trees, ornamentals, lawns, nurseries, etc. FLRs can be applied to soil, substrate or foliage, depending on the form and type of fertilizer. FLRs can be combined with other conventional or organic fertilizers to complement plant nutrition.
What advantages do slow release fertilizers have?
FLRs have multiple advantages, such as:
*Improve the use of nutrients by plants, which translates into greater yield and quality of crops.
* Reduce the frequency and amount of fertilizer applications, saving time, money and energy.
* Preserve soil health by avoiding salt accumulation and acidification.
* Protect water by reducing pollution by nitrates and phosphates.
* Contribute to the mitigation of climate change, by reducing emissions of greenhouse gases such as nitrous oxide.
What disadvantages do slow release fertilizers have?
Slow release fertilizers also have some disadvantages, such as:
• Have a higher initial cost than conventional fertilizers, which can limit their accessibility and profitability.
• Depending on environmental and biological factors that can alter the release of nutrients, such as humidity, temperature, pH or microbial activity.
• Present a lower availability of some nutrients, such as phosphorus or potassium, which can be fixed by the soil or substrate.
• Require adequate management, which takes into account the characteristics of the soil, climate, crop and fertilizer, to optimize its effectiveness and avoid possible risks.
Conclusion
Slow release fertilizers are an efficient and sustainable option for plant nutrition, which contributes to improving the productivity and profitability of crops, while respecting the environment. However, its use requires adequate management, which takes into account the characteristics of the soil, climate, crop and fertilizer, to optimize its effectiveness and avoid possible risks. Therefore, it is recommended to consult an expert or a reliable source of information before applying them.
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