Currently, eucalyptus is the main cultivated forest species in Brazil, occupying approximately 771 TP3T of the total area of planted forests (IBÁ, 2020). Its rapid growth, high productivity, and multiple uses (paper, pulp, furniture, flooring, charcoal, and civil construction) make it an attractive and profitable crop (Amorim et al., 2021). Although it is considered a plant with low soil fertility requirements, evidence of nutritional deficiency has been found in areas with eucalyptus plantations without supplemental fertilization (Silveira et al., 1995).
An interesting characteristic found in some eucalyptus species is the mutualistic association between fungi and roots, allowing for better nutrient utilization (Araújo et al., 2004). The organomineral fertilizers developed by ILSA combine the supply of nutrients through mineral and organic sources, favoring the biological activity of the soil. This is because the AZOGEL organic matrix is beneficial to overall soil health due to its low C/N ratio, which helps maintain microorganism populations, promoting improved soil health without causing nitrogen immobilization for crops.
One of the central points in eucalyptus management is nutrient cycling. The litter formed in plantations is fundamental for soil stability, helping in vegetation recovery and erosion reduction (Carvalho et al., 2017). Furthermore, a significant portion of the absorbed nutrients returns to the soil via forest residues such as branches, bark, leaves, and shoot tops (Melo, 2014). These compartments contain approximately 65% of N, 70% of P, and 64% of K assimilated by the trees, varying according to the age and management of the forest (Santana et al., 2008). Even so, since there is a significant export of nutrients during harvesting, fertilization becomes essential to replenish these elements and guarantee the productive longevity of the plantations. Within this context, fertilization stands out as one of the most important management practices, as it ensures the proper development of seedlings, the maintenance of productivity over the years, the sustainability of forest production systems, and the quality of the product.
Symptoms of deficiency and the main responses to fertilization are observed primarily for phosphorus, nitrogen, potassium, calcium, and magnesium. Phosphorus deserves special mention as it is a crucial nutrient for the initial growth of eucalyptus, especially in tropical soils where its fixation is high. Phosphorus deficiency in the first months compromises root development and, consequently, the absorption of water and other nutrients, reducing the growth potential of the forest. Among micronutrients, boron and zinc stand out, especially in tropical soils. In more sandy areas with low water retention, responses to fertilization tend to be more evident, highlighting the importance of regionalized management according to the conditions of each soil (Silva & Bellote, 2021).
In practical terms, eucalyptus fertilization can be divided into planting, topdressing, and maintenance fertilization. The first should be carried out when the seedlings are established. At this time, it is recommended to apply 10 to 40 liters of nitrogen (N) and potassium (K) and 10 liters of phosphorus (P) (Gonçalves, 1995; Silveira et al., 2001). The application of micronutrients such as boron, zinc, and copper is also recommended. This step is crucial for initial growth, especially in the first months after planting, when the root system is still developing.
Subsequently, topdressing fertilization is carried out, starting 30 to 40 days after transplanting, generally in split applications. Splitting applications is a strategy to increase fertilization efficiency and avoid losses, especially in regions subject to heavy rainfall or long periods of drought. At this stage, the most important nutrients are nitrogen and potassium, essential for sustaining the initial growth of the forest (Silveira & Malavolta, 2000; Andrade, 2004). Applications can extend from 3 to 24 months after planting, following the development of the trees, mainly in relation to canopy closure. In this sense, it is noteworthy that the availability of nutrients from AZOGEL-based organic fertilizers is slow and gradual, making the nutrients available throughout the crop cycle, reducing the need for split applications. Generally, between 30 and 36 months of age, maintenance fertilization is carried out to replenish the nutrients exported by harvesting, especially potassium, calcium, and magnesium.
In this context, two ILSA solutions stand out, developed to meet the nutritional demands of eucalyptus: FERTIL and HyperActive. FERTIL is a high-efficiency, slow-release organic nitrogen fertilizer produced with AZOGEL, containing 12.5% of N. This ensures a constant supply of N throughout the plants' production cycle. Furthermore, this fertilizer has a low C/N ratio, favoring mineralization and the use of N from the input itself, without needing to draw on soil N.
HyperActive stands out as a strategic source of phosphorus, the most required nutrient by eucalyptus. Its formulation combines two forms of P, one with immediate release and the other with gradual release, ensuring adequate supply both at the initial start and throughout the forest's development. Associated with humic and fulvic acids, HyperActive improves soil conditions in the rhizosphere, reduces losses due to fixation, increases fertilization efficiency, and promotes greater biological activity. Another benefit is that it favors the aggregation of soil particles, increasing porosity and water retention, which contributes to the forest's resistance during periods of drought.
Eucalyptus fertilization should always be planned based on soil analysis and adapted to the climate, texture, and fertility conditions of each region. More than a tool to increase productivity, it is an essential practice to guarantee the longevity of planted forests and the quality of the products. In this context, fertilizers that combine mineral and organic sources with immediate and gradual release technologies, such as FERTIL and HyperActive, represent a strategic advance in forest management, ensuring greater efficiency and sustainability of production systems.
Bibliographic references
Amorim, VSS et al. The environmental benefits of eucalyptus planting: a literature review. Research, Society and Development, v. 10, n. 11, e318101119604, 2021
Andrade, LRM. Soil amendments and fertilizers for perennial and semi-perennial crops. In: SOUSA, DM & LOBATO, E. Cerrado: Soil correction and fertilization. 2nd ed. Brasília, DF: Embrapa Informação Tecnológica, 2004. Chapter 13, pp. 317-366.
Araújo, CV et al. Arbuscular mycorrhiza in Eucalyptus cloeziana F. Muell plantations on the northern coast of Bahia, Brazil. Acta Bot. Bras., v. 18, n. 3, p. 513-320, 2004
Carvalho, DC et al. Nutrient cycling of a eucalyptus plantation in the regeneration of native species in the understory. Revista Floresta, v. 47, n. 1, p. 17-28.
Gonçalves, JLM. Fertilization recommendations for Eucalyptus, Pinus and typical species of the Atlantic Forest. Esalq/USP: Forestry Documents, 1-23, 1995.
IBÁ – Brazilian Tree Industry. IBÁ Annual Report 2020.
Melo, EASC. Nutrition and fertilization of clonal eucalyptus plantations under different edaphoclimatic conditions. Master's thesis. Esalq/USP, 2014. 187p.
Santana, R. C. et al. Nutrient allocation in eucalypt plantations in Brazil. Revista Brasileira De Ciencia Do Solo, Campinas. v. 32, p. 2723-2733, Nov-Dec 2008.
Silveira, RLVA et al. In: BRAZILIAN CONGRESS OF SOIL SCIENCE, 1995, Viçosa. Survey of the nutritional status of Eucalyptus grandis forests in the Itatinga region – SP. I – Macronutrients. Campinas: Brazilian Society of Soil Science, 1995. p. 896-898.
Silveira, RLVA; Malavolta, E. Potassium nutrition and fertilization in Eucalyptus. Agronomic Information, Piracicaba, n. 91, 2000. 12 p.
Silveira, RLVA et al. Be a doctor of your eucalyptus. Agronomic Information, Piracicaba, no. 93, 2001. 23 p.
Silva, HD; Bellote, AFJ Eucalyptus – Liming and fertilization. Embrapa, 2021. Available at: https://www.embrapa.br/agencia-de-informacao-tecnologica/cultivos/eucalipto/producao/implantacao/calagem-e-adubacao
Authors
Agr Eng. MSc. Isabela Bulegon Pilecco
Agricultural Eng. Msc. Thiago Stella de Freitas
Agricultural Engineer Tuíra Barcellos
