Emir. J. Food Agric ● Vol 32 ● Issue 1 ● 2020 19 Nutrition and physiology of hybrid Eucalyptus urograndis in soil fertilized with sewage sludge Alessandro Reinaldo Zabotto 1 , Leticia Danielle Longuini Gomes 1 , Caroline de Moura D’andréa Mateus 2 , Roberto Lyra Villas Boas 2 , Shoey Kanashiro 1 , Armando Reis Tavares 3 * 1 Instituto de Botânica, Av. Miguel Stefano, 3687, São Paulo, SP, Brazil, 2 Universidade Estadual Paulista “Júlio de Mesquita Filho” (UNESP), Av. Universitária, 3780, Botucatu, SP, Brazil, 3 Instituto Agronômico de Campinas, Avenida Luiz Pereira dos Santos, 1.500, Jundiai, SP, Brazil INTRODUCTION The most important destination for sewage sludge is in agriculture since it is rich in nutrients and, consequently, an excellent organic fertilizer (Contin et al., 2012). Sewage sludge has high contents of organic matter and nitrogen, as well as other minerals of agronomic interest (Lima et al., 2011). The use of sewage sludge and its potential for use as fertilizer and soil conditioner represent the possibility of reducing the use of mineral fertilizers and increasing crop productivity (Guedes et al., 2006), as long as it is used according to appropriate procedures to minimize environmental and ecological impact (Usman et al., 2012). Sewage sludge improves soil fertility by increasing cation exchange capacity (CEC) when incorporated into soil, reducing concentrations of exchangeable aluminum and increasing soil microbial activity, as well as improving its physical and biological attributes. It is also a source of macro- and micronutrients for plants (Prado and Cunha, 2011). In contrast, sewage sludge contains high amounts of heavy metals that can cause environmental damage, polluting the soil and groundwater and presenting toxicity to plants (Bettiol and Ghini, 2011). Use of the parameters and procedures defned in Resolution 375/2006 of CONAMA - National Environment Council (CONAMA, 2006) for sewage sludge should be considered. Eucalyptus forest plantations are economically and ecologically important in Brazil, producing several products and raw materials, mostly for the timber and cellulose industry, and contributing to deforestation reduction owing to the replacement of wood from native forests for those of cultivated forests (Moreira et al., 2017). The production cycle of the crop is long, requiring the application of slow release fertilizers because the soils used for forest plantations are usually poor in nutrients (Ibrahim et al., 2019). Several studies have been carried out with the use of sewage sludge in forest plantations; Sewage sludge is a residual pollutant product from the treatment of urban effuent and must be adequately processed before fnal disposal in order to avoid environmental contamination. The use of sewage sludge in agricultural and forestry areas can improve the physical, chemical and biological properties of soil; it can also be a source of nutrients, increasing crop productivity. Accordingly, this study aimed to evaluate the growth and development of hybrid Eucalyptus urograndis (Eucalyptus grandis x E. urophylla) seedlings cultivated in soil with different doses of sewage sludge. To accomplish this, hybrid E. urograndis seedlings were cultivated for 120 days in pots containing soil (dystrophic Red-Yellow Latosol -LVA) with different doses of sewage sludge (0, 30, 60 or 90 Mg ha -1 ). The experiment was carried out in a randomized complete block design consisting of four treatments, three replications with four plants per replication, totaling 48 plants. Biometric, biomass and physiological variables (chlorophyll, gaseous exchange, stomatal conductance and transpiration); in addition to macro- and micronutrient contents in leaves and soils of each treatment were evaluated. The treatments with sewage sludge were statistically superior to control treatment for all variables. Therefore, we recommend the application of 60 Mg ha -1 sewage sludge for the growth of hybrid Eucalyptus urograndis seedlings. Conversely, 90 Mg ha -1 sewage sludge inhibited hybrid E. urograndis root growth. Moreover, the use of sewage sludge as organic fertilizer in tropical soils is a viable and sustainable alternative for Eucalyptus cultivation. Keywords: Biosolid; Eucalyptus; Fertilization; Organic nutrition ABSTRACT Emirates Journal of Food and Agriculture. 2020. 32(1): 19-24 doi: 10.9755/ejfa.2020.v32.i1.2054 http://www.ejfa.me/ RESEARCH ARTICLE *Corresponding author: Armando Reis Tavares, Instituto Agronômico de Campinas, Avenida Luiz Pereira dos Santos, 1.500, CEP 13214-820, Jundiai, SP, Brazil. E-mail: atavares2005@yahoo.com.br Received: 01 August 2019; Accepted: 30 December 2019