Solid urban waste in the production of Aegiphila sellowiana Cham . seedlings

Resíduos sólidos urbanos na produção de mudas de Aegiphila sellowiana Cham. R E S U M O A utilização de resíduos orgânicos como fonte primária de nutrientes pode contribuir para a redução da dependência de insumos, além de ser uma destinação sustentável para esses materiais. Objetivou-se avaliar a qualidade de mudas de Aegiphila sellowiana desenvolvidas em substratos constituídos por proporções distintas de lodo de esgoto, resíduos orgânicos e vermiculita. Foram testados 26 substratos (tratamentos) formulados a partir da mistura de lodo de esgoto com vermiculita e os resíduos fibra de coco, palha de café in natura, composto orgânico (esterco bovino não curtido e palha de café in natura), casca de arroz carbonizada e casca de arroz in natura, nas proporções de 100:0, 80:20, 60:40, 40:60 e 20:80 (lodo de esgoto:materiais), e uma testemunha, constituída por substrato comercial (Bioplant®). Aos 120 dias após a semeadura, foram determinadas as características morfológicas diâmetro do coleto, altura da parte aérea, massa seca (parte aérea, raízes e total) e calculado o índice de qualidade de Dickson (IQD) de todas as plantas. Os substratos formulados com lodo de esgoto e composto orgânico proporcionaram o maior crescimento das mudas (40% LE:60% CO e 20% LE:80%). Recomendam-se as proporções de 20 a 40% de lodo de esgoto e de 60 a 80% de composto orgânico para produzir mudas de A. sellowiana.


Introduction
The increasing demand for projects of recovery of degraded areas (RDAs) increases the need to produce seedlings of forest species native to Brazil (Kratka & Correia, 2015), opening new perspectives for species like Aegiphila sellowiana Cham.(Lamiaceae).Found in the Atlantic Forest region, A. sellowiana has great potential for RDAs due to its fast growth and production of large amount of fruits consumed by several bird species.In addition, it is a pioneer species and a heliophyte (Lorenzi, 2008), very useful to initiate the process of succession in open areas, exposed to solar radiation.
The use of industrial or urban wastes to compose substrates for production of seedlings of forest species has increased in the last years, being an economically viable alternative to guarantee the supply of raw material in the long term and at low cost (Caldeira et al., 2012a).In addition, it collaborates with the reduction of this environmental problem (Trazzi et al., 2014), since there is large production of this waste due to the populational growth.
Reuse of wastes such as sewage sludge becomes a low-cost option for its management and disposal, which are complex and expensive, besides the possibility of transforming this material that is currently seen as garbage in a commodity (Guerrini et al., 2017).Several studies point to the use of sewage sludge as a viable alternative to supply organic matter and nutrients in the formulation of substrates for production of seedlings of native forest species (Trazzi et al., 2014;Trigueiro & Guerrini, 2014;Kratka & Correia, 2015;Abreu et al., 2017).Sewage sludge can be an excellent unconventional source of nitrogen and potassium for wood production in nutritionally poor tropical soils (Abreu Júnior et al., 2017).
Considering the potentials of using sewage sludge in the formulation of substrates for production of good-quality seedlings and that its utilization brings environmental benefits and reduces the costs of seedling production, the present study aimed to evaluate the quality of A. sellowiana seedlings grown in substrates composed of different proportions of sewage sludge, organic wastes and vermiculite.

Material and Methods
A. sellowiana seedlings were produced between July and November 2012 in the nursery of the Experimental Area I at the Center of Agrarian Sciences and Engineering of the Federal University of Espírito Santo -UFES, in the municipality of Brazil (20º 45' S;41º 31' W).The mean altitude of the experimental area is 120 m and the climate of the region is Cfa (rainy season in the summer and dry season in the winter), according to Köppen's classification.The mean annual temperature is 23 ºC and mean annual rainfall is around 1,200 mm (Alvares et al., 2013).
The OC was produced using fresh bovine manure, from livestock activities of the Experimental Area I of the Center of Agrarian Sciences and Engineering of UFES, and fresh coffee straw donated by rural producers of the region of the Caparaó National Park, ES.These two wastes were mixed in equal volumes and remained for 60 days in open environment for biological stabilization.After this process, the material was passed through a 2-mm-mesh sieve for homogenization (Caldeira et al., 2008;Delarmelina et al., 2013).The SS came from the Sewage Treatment Station of the company Foz do Brasil S.A., located in the municipality of Cachoeiro de Itapemirim -ES.The SS was obtained after treatment in anaerobic filter, and the concentrations of chemical compounds and characteristics of this material are described in the study of Santos et al. (2014).
Physical characterization of the substrates was carried out in three samples (replicates) for each waste and treatment (MAPA, 2007).The experimental design was completely randomized, with five replicates of eight plants (sampling unit) and 26 treatments.
A. sellowiana seeds were obtained at the IPEF (Forest Science and Research Institute) from Capão Bonito -SP, 2012 season.Sowing was performed manually and each 280-cm 3 tube received four seeds.These tubes were placed on trays with capacity for 54 tubes.The trays were arranged on suspended beds at 80 cm height from the soil, in a shade house covered with 50% shading screen.To ensure the supply of nutrients to the seedlings, 750 g of ammonium sulfate (20% N), 1667 g of single superphosphate (18% P 2 O 5 ) and 162 g of potassium chloride (58% K 2 O) were added per m 3 of substrate, according to the recommendation proposed by Gonçalves et al. (2000).
After emergence, when the seedlings had two pairs of leaves and were about 5 cm tall, thinning was performed, leaving only one seedling per tube.The plant which was most centralized in the tube and with greatest shoot growth was selected.The seedlings remained in the shade house (50% shading) and were irrigated four times a day by an automatic irrigation system, twice in the morning and twice in the afternoon, totaling a 16-mm water depth per day.On rainy days, plants were not irrigated.
At 120 days after sowing, the following growth variables were measured: collar diameter (D), shoot height (H), root dry matter (RDM), shoot dry matter (SDM), total dry matter (TDM), H/D ratio, SDM/RDM ratio, and Dickson quality index (DQI).To obtain SDM and RDM, the plant parts were separately weighed after drying in forced air circulation oven at 65 ºC, for a period of approximately 72 h.DQI was obtained by the formula of Dickson et al. (1960).
After obtaining the dry matter, seedling shoots were ground in a knife mill, with 30-mesh sieve, and three samples per treatment were collected for the determination of N, P, K, Ca, Mg and S contents, following the methodology described by Malavolta et al. (1997).Nutrient accumulation in the shoots of the seedlings was calculated by taking into account the contents of nutrients multiplied by their respective values of shoot dry matter.
The data were subjected to analysis of variance (ANOVA) (p < 0.05) and, when significant, the Scott-Knott test was applied to compare differences between means using the R software.
Evaluating the nutritional characteristics of the same substrates used here, Santos et al. (2014) reported that treatments formulated with SS and OC were considered as more adequate for the growth of seedings of forest species.The treatments T16-40% SS/60% OC and T17-20% SS/80% OC (Table 1) led to the highest means of diameter (D), shoot dry matter (SDM) and total dry matter (TDM).These two treatments and T15-60% SS/40% OC resulted in the highest values of root dry matter (RDM).The treatment T16 favored the growth of the seedlings in height (H).The growth characteristics cited were superior in these treatments compared with the commercial substrate (T26-100% CS).
Only the treatments with SS and OC (T14-80% SS + 20% OC, T15-60% SS/40% OC, T16-40% SS + 60% OC and T17-20% SS + 80% OC) and the T11-60% SS + 40% FCS led to seedlings with H within the limit between 20 and 35 cm (Table 1), considered as ideal for seedlings of native forest species to be taken to the field (Gonçalves et al., 2000).As observed in the present study, the use of substrates formulated using SS and OC resulted in the best means of H in Sesbania virgata seedlings (Delarmelina et al., 2013).The growth in H of Mimosa scabrella seedlings was also low when the substrates combined SS with CRH (Kratz et al., 2013a).
Collar diameter is an important variable in the evaluation of seedling quality and is related to the capacity for establishment in the field (Silva et al., 2012).Gonçalves et al. (2000) consider D as adequate for seedlings of forest species when it is between 5 and 10 mm.The substrates which met these specifications were all treatments formulated with SS plus OC or FCS and also the treatments T18-80% SS/20% CRH, T19-60% SS/40% CRH and T22-80% SS/20% FRH (Table 1).As observed for H, the highest means of D occurred in the substrates formulated with OC, which led to increase in substrate fertility, especially with respect to P, N, Ca and Mg, as described by Santos et al. (2014).
The highest values of dry matter (SDM, RDM and TDM) (Table 1) were observed in the treatments which had contents above 40% of organic compost in substrate composition.Studying the growth of Sesbania virgata seedlings, Delarmelina et al. (2013) also found higher means of SDM in treatments formulated with organic compost.
Substrates formulated with up to 60% sewage sludge led to higher RDM accumulation (Gomes et al., 2013;Trigueiro & Guerrini, 2014).Proportions higher than 60% sewage sludge did not favor the increment in RDM, probably because of the undesirable alterations in the physical characteristics (density, macroporosity and microporosity) that the use of high concentrations of sewage sludge can cause in the substrate (Gomes et al., 2013).
Based on the H/D ratio (Table 1), it can be observed that the treatment T11-60% SS/40% FCS resulted in the highest mean, followed by the treatment T16-40% SS/60% OC.However, because of the disproportionate growth of H and D, the ratio between these parameters in all treatments remained below that considered as ideal, from 5.4 to 8.1 (Carneiro, 1995).The H/D ratio, also called robustness coefficient (Gomes et al., 2002), varies with species, type and proportion of the substrate, container volume, management of seedlings in the nursery and age at which the seedling is evaluated (Gomes et al., 2013).This suggests further research to determine the ideal values of the H/D ratio of native species (Delarmelina et al., 2013).
The treatments T11-60% SS/40% FCS and T17-20% SS/80% OC led to higher SDM/RDM ratio (Table 1) and were the only ones which reached the SDM/RDM ratio of 2:1, as suggested by Caldeira et al. (2008).These authors also point out that it is important to analyze this ratio when the seedlings are taken to the field, because their shoots should not be much greater than the roots, due to possible problems related to absorption of water for the shoots or lodging.
Seedlings in the treatments T15-60% SS/40% OC, T16-40% SS/60% OC, T17-20% SS/80% OC and T18-80% SS/20% CRH had the highest values of DQI (Table 1).The higher the value of this parameter, the better the quality of the seedlings (Gomes et al., 2002), because they show low H/D ratio (without etiolation), balance in the SDM/RDM ratio (seedlings with root system capable of supplying the shoots) and high values of biomass (Abreu et al., 2017).Nonetheless, DQI may vary according to species, management of seedlings in the nursery, type and proportion of substrate, container volume, and mainly the age at which the seedling is evaluated (Caldeira et al., 2012b).
The treatment with 100% sewage sludge (T1) was not efficient for the production of A. sellowiana seedlings, as also observed in Schinus terebinthifolius Raddi seedlings (Caldeira et al., 2008).It can be noted that, as the percentage of sewage sludge increases in the substrate, there is an increase in bulk density and microporosity and reduction in macroporosity (Table 2), as observed in the study conducted by Kratz et al. (2013b).However, these characteristics are useful when sewage sludge is used in combination with low-density highmacroporosity wastes such as coconut fiber, rice husk and coffee straw.Despite having satisfactory chemical attributes, sewage sludge needs to be mixed with other components to provide balance between supply of nutrients and physical R. Bras.Eng.Agríc.Ambiental, v.22, n.12, p.831-836, 2018.conditions, such as aeration and water retention (Caldeira et al., 2012b).
The commercial substrate (T26) was not considered as ideal for the production of A. sellowiana seedlings (Table 1), Table 3. Means and standard deviation of nutrient accumulation in the shoots of Aegiphila sellowiana seedlings produced in different substrates because these seedlings did not show minimum H of 20 cm and H between 5 and 10 mm (Gonçalves et al., 2000).This result can be related to physical factors, such as total porosity of 89.45% (Table 2), which exceeded the reference values considered as ideal.Caldeira et al. (2013) observed that high values of total porosity (above 85%) in the commercial substrate can hamper the initial growth of Chamaecrista desvauxii (Collad.)seedlings, as observed in the present study.Although the highest means of P, Ca and Mg contents were found in the commercial substrate (Santos et al., 2014), seedlings in this treatment showed RDM higher than SDM (Table 1), which can be related to the water availability of the substrate.
Corroborating the results of SDM for A. sellowiana seedlings, the treatments formulated with SS and OC led to greater accumulation of macronutrients in their shoots (Table 3).
In the present study, the decreasing order of accumulation of nutrients in the shoots was N > Ca > K > P > Mg > S. Highest N accumulation in the shoots of the seedlings was observed in the substrate formulated with 60% OC (Table 3) because this treatment led to higher mean of SDM (Rocha et al., 2013).Ca contents in the tissues of the seedlings are correlated with the available contents of this nutrient in the substrate, which explains its higher accumulation in the shoots, in general, under higher proportions of sewage sludge.
The treatments T24-40% SS/60% FRH and T25-20% SS/80% FRH did not allow adequate growth of A. sellowiana seedlings.These treatments led to the lowest means of H, D and dry matter (Table 1) and, therefore, should be avoided.Lowest accumulations of all nutrients evaluated in the shoots were also observed in these treatments.This result may be linked to the low values of available water (AW) (Table 2) found in these treatments.
Sewage sludge proved to have positive effects on the growth of A. sellowiana seedlings.This waste improved substrate fertility with increment in the contents of nutrients, especially P and N (Santos et al., 2014;Trigueiro & Guerrini, 2014;Abreu et al., 2017).However, sewage sludge requires the addition of other components to provide balance between supply of nutrients and physical conditions, such as aeration and water retention (Kratz et al., 2013a).The quality of seedlings produced with substrates containing sewage sludge in their composition can be confirmed by conducting experiments to analyze their performance in the field.

Conclusions
1. Sewage sludge alone is not an adequate substrate for the production of A. sellowiana seedlings.

Table 1 .
Means and standard deviation for the growth variables of Aegiphila sellowiana seedlings produced in different substrates with sewage sludge SS -Sewage sludge; CF -Coconut fiber; VER -Vermiculite; FCS -Fresh coffee straw; OC -Organic compost; CRH -Carbonized rice husk; FRH -Fresh rice husk; CS -Commercial substrate; H -Shoot height; D -Collar diameter; RDM -Root dry matter; SDM -Shoot dry matter; TDM -Total dry matter; DQI -Dickson quality index *Means followed by the same letter, in the column, do not differ statistically by Scott-Knott test.**Significant (p < 0.05); ***Coefficient of variation