SEWAGE SLUDGE COMPOST ASSOCIATED TO FREQUENCY OF IRRIGATION FOR Peltophorum dubium (Sprengel) Taubert SEEDLINGS PRODUCTION

Abstract

Inappropriate disposal of sewage sludge has become an environmental problem. In some Brazilian states, such as São Paulo, in natura sewage sludge use is practically prohibited due to restrictive requirements by CONAMA Resolution No. 375/2006. Therefore, a very promising alternative to reuse this residue is to compost it with other materials and use it as a substrate in the production of seedlings. The objective of this study was to evaluate the development of the seedlings of Peltophorum dubium in compost with sewage sludge, to determine which frequency of irrigation would be more adequate according to the physical characteristics of each substrate, and if this would influence the morphological and nutritional variables of the seedlings. Two composts were produced: sewage sludge composted with sugarcane bagasse and sewage sludge composted with eucalyptus bark, both in 1: 1 proportion. Commercial substrate was used for control. This study was completely randomized in a 3x3 factorial design, which three substrates and three frequencies of irrigation were tested: two, three and four times per day. The evaluated parameters were: plant height, stem diameter ratio, shoot / root ratio, leaf dry mass, root dry mass, total dry mass, green color index, Dickson quality index (IQD), water loss through leaching and substrate water retain capacity. The best results were observed in the seedlings produced in sewage sludge compound with eucalyptus bark submitted to the frequencies of two or three times a day.

Composted Sewage Sludge as a Substrate for Commercial Seedlings of Peltophorum dubium (Spreng.) Taub.

“…It is expected that sewagesludge-based biosolids have high macro-and micronutrient concentrations [31]. In contrast, commercial substrates (CSs) tend to be inert [25]. The high P and K amounts observed in CSs are due to the well-known presence of superphosphate added during its development process, mixed with carbonized rice husks, i.e., a potassium-rich material [32].…”

“…Posteriorly, the seedlings were separated into beds with transparent plastic to receive each treatment. The irrigation consisted of a 12 mm water blade with a twice-daily frequency [25].…”

Composted sewage sludge as an alternative substrate for forest seedlings production

“…Regardless of irrigation depths, SEB provided seedlings with the largest amount of dry mass, although seedlings produced using 6 mm irrigation depth presented lower values than seedlings produced in SCB. Other studies using sugarcane bagasse and sewage sludge as substrate obtained better morphological characteristics of Eucalyptus and Peltophorum dubium seedlings growing under adequate irrigation depths (Gabira et al 2020a, Manca et al 2020, Silva et al 2020a). The lower total porosity values of SEB may have hindered the growth of the root system of seedlings under a low irrigation depth, making it difficult for water to go beyond the superficial region of the tube.…”

Crescimento de mudas de Poincianella pluviosa (DC.) L.P.Queiroz em diferentes substratos e lâminas de irrigação

“…A resposta observada para P. pluviosa foi semelhante a outros trabalhos que utilizaram lodo de esgoto como componente de substrato para produção de mudas de diferentes espécies de leguminosas arbóreas, como Cabreira et al (2017) e Silva et al (2020) para Peltophorum dubium, Caldeira et al (2012) para Ateleia glazioveana e Faria, Caldeira, Delarmelina e Gonçalves (2013) para Mimosa setosa. Em geral, os autores relatam que o acréscimo desse material em substratos favorece o crescimento e a qualidade das mudas, tendo em vista seus altos teores de nutrientes e matéria orgânica.…”

“…Por outro lado, o seu manejo correto é determinante para a qualidade das mudas, podendo reduzir o seu tempo de formação (Wendling e Gatto, 2012). A irrigação exerce influência direta na qualidade das mudas, a quantificação hídrica na fase de formação é muito importante, pois a falta ou o excesso prejudicam a produção (Morais, Susin, Vivian e Araújo, 2012;Silva et al, 2020).…”