Uso agrícola dos efluentes de tratamento de esgoto: implicações agronômico-ambientais e perspectivas para o Brasil

In many studies worldwide the use of treated sewage effluents (TSE) as water and nutrient sources in agricultural irrigation have been introduced as a viable alternative for wastewater destination in the environment. Considering agronomic and environmental aspects the objectives of this review were: (i) to present an overview of TSE irrigation on different agro-systems (annual crops, orchards, forests and forages); and (ii) to show the principal changes on chemical, physical and microbiological soil characteristics after TSE application. Various studies have revealed that the nutrient supply only by TSE irrigation was not sufficient to meet plant nutrient requirements resulting in yield decreases. The problem could be solved by an adapted effluent/fertilizer management. Moreover, TSE could generally substitute efficiently freshwater for irrigation. Regarding soil quality conditions, TSE irrigation affected mainly: (i) total soil carbon and nitrogen, and mineral nitrogen in soil solution; (ii) microbial activity, composition of microbial communities and their function; (iii) exchangeable calcium and magnesium; (iv) salinity, sodicity, clay dispersion and hydraulic conductivity. Other soil parameters considered in this review (e.g. heavy metals) did not present significant changes over short and medium terms. Due to the often observed accumulation of sodium and nitrogen losses (leaching, volatilization and denitrification) after TSE irrigation, the monitoring of these components is of crucial importance for a sustainable use. Finally, further studies on the technical-economical-environmental viability of TSE irrigation are required to establish reliable recommendations for TSE use particularly in Brazilian agro-systems.O uso dos efluentes de tratamento de esgoto (ETEs) como fonte d'água e nutrientes na agricultura (via irrigação) tem sido, em diversos locais, uma alternativa viável para a disposição das águas residuárias no ambiente. Os objetivos dessa revisão foram: (i) enfocar aspectos agronômicos e ambientais concernentes ao uso de ETEs em diferentes agrossistemas (culturas anuais, fruticultura, florestas e forragens); (ii) enfatizar as principais mudanças nas características químicas, físicas e microbiológicas dos solos irrigados com ETEs. Foram observados que, em diversos trabalhos, a irrigação com ETEs não foi suficiente para atender a demanda nutricional das plantas, resultando em diminuição no rendimento. Esse problema poderia ser resolvido mediante adequação do manejo da fertilização e irrigação. Além disso, os ETEs poderiam substituir eficientemente a água doce normalmente empregada na irrigação. Quanto a qualidade de solo, a irrigação com ETEs tem alterado principalmente os parâmetros: (i) carbono total e nitrogênio total no solo e nitrogênio mineral na solução no solo; (ii) atividade, composição e função da comunidade microbiana; (iii) cálcio e magnésio trocáveis; (iv) salinidade, sodicidade, dispersão de argilas e condutividade hidráulica. Outros parâmetros de qualidade de solo (por exemplo, metais pesados) não apresentaram mudanças significativas em curto e médio prazo. O monitoramento da acumulação de sódio e das perdas de nitrogênio (lixiviação, volatilização e denitrificação) é crucial para o uso sustentável dos ETEs na irrigação. Finalmente, mais estudos são necessários para mostrar a viabilidade técnico-econômico-ambiental, objetivando-se a recomendação segura dos ETEs na irrigação dos agrossistemas brasileiros

Balance of the nutrients Ca+2, Mg+2, Na+, K+ e NO3 on a first order catchment covered with Natural vegetation in Central Amazonia

The study was conducted on a first-order catchment of about 3.5 km2 located on an experimental site 16 km west of the Manaus - Boa Vista highway, and 60 km north of Manaus. The main purpose was to quantify the balance of the nutrients Ca+2, Mg+2 Na+, K and NO3 through the comparison of the values of rainfall input versus streamflow output. Water sampling and nutrient flux determinations were carried out on a monthly basis for a one year period. Ionic concentrations showed low variation along the period. The highest concentrations in the rainfall were related to the accumulation of aerosols in the atmosphere, after a long rainless period. The vegetation exerted, apparently, more influence on nitrate, over the other nutrients. The nutrient flux varied, where their total input was attributed to individual storms of great magnitude. The balance, expressed in kg.ha-1,year1, was positive for all nutrients, with the following net gain values: Ca+2 (2,33); Mg+2 (1,66); Na+ (2,07); K+ (1,80) and NO3 (5,84).O estudo foi conduzido em uma bacia hidrográfica experimental de primeira ordem de aproximadamente 3,5 km2 localizada próximo ao km 16 da estrada secundária ZF-02, do km 60 da rodovia BR-174 que liga Manaus - Boa Vista. O principal objetivo foi quantificar o balanço dos nutrientes Ca+2, Mg+2 Na+, K+e NO3 através da entrada via precipitação e saída via deflúvio. As coletas de água e os cálculos do fluxo de nutrientes foram feitos em base mensal por um período de um ano. Observou-se que as concentrações iônicas apresentaram pouca variação ao longo do tempo. As maiores concentrações na precipitação ocorreram em função do acúmulo de aerosóis na atmosfera, após um período longo sem chuva. Aparentemente a vegetação exerceu influência mais evidente sobre o nitrato em relação aos demais nutrientes. O fluxo dos nutrientes foi variável, onde principalmente a entrada total destes deu-se em função de eventos individuais de chuva de grande magnitude. O balanço em kg.ha-1.ano-1 foi positivo para todos os nutrientes com os seguintes ganhos líquidosCa+2 (2,33); Mg+2 (1,66); Na+ (2,07); K+ (l,80) e NO3 (5,84)

EFEITO DE INOCULANTES BACTERIANOS NO BIOCONTROLE DO MÍLDIO E PRODUTIVIDADE DE CEBOLA

Entre as doenças que ocorrem na cultura da cebola (Allium cepa L), o míldio causado por Peronospora destructor, tem sido considerada uma das mais destrutivas na cultura no sul do Brasil. Na rizosfera, região do solo que circunda a raiz e está sob a influência do sistema radicular, predominam bactérias de vida livre ou associadas aos tecidos das plantas. O termo rizobactéria caracteriza as bactérias da rizosfera que colonizam as raízes, denominadas rizobactérias promotoras de crescimento vegetal (RPCV) quando apresentam efeitos positivos sobre as culturas. As rizobactérias exercem efeito benéfico sobre as plantas por diferentes mecanismos de ação, diretos ou indiretos, como, por exemplo, a antibiose, o parasitismo, a competição, a produção de sideróforos e a indução de resistência. As rizobactérias são capazes de se multiplicar e colonizar rapidamente o sistema radicular, prevenindo a invasão de patógenos pela produção de metabólitos secundários que inibem outros microrganismos deletérios. Dentro deste aspecto, o objetivo deste trabalho é avaliar o efeito de diferentes inoculantes bacterianos no manejo do míldio e produtividade da cebola. Em experimento em blocos casualizados com três repetições foram utilizadas mudas de cebola cultivar Valessul com nove semanas de idade oriunda de sementes microbiolizadas durante quinze minutos com inoculantes a base de Bacillus subtilis, B. amyloliquefaciens e B.pumilus; Pseudomonas fluorescens e Azospirillum brasilense; Azospirillum brasilense e também com reinoculação durante trinta minutos no momento do transplantio com os mesmos inoculantes da semente, além das mudas microbiolizadas apenas no transplantio respectivamente com mesmos inoculantes e testemunha sem inoculante em parcela constituídas de uma área de 1,5 X 1,30 m, contendo 4 linhas espaçadas a 30 cm e 10 cm entre plantas, totalizando 60 plantas, equivalente a 400.000 planta.ha-1. Cinco plantas em cada repetição foram previamente escolhidas e demarcadas aleatoriamente para a avaliação do míldio e da produtividade. A severidade da doença ao longo do ciclo foi integralizada e calculada a área abaixo da curva de progresso da doença (AACPD) e a avaliação da produtividade comercial total (bulbos com diâmetro transversal acima de 35 mm) foi realizada no final de 22 semanas após o transplantio. As médias obtidas da AACPD, severidade e da produtividade (Kg.ha-1) foram submetidas à análise de variância pelo teste de F e se significativas comparadas pelo teste de Tukey 5%. Não foi significativa a diferença estatística entre AACPD, severidade final e produtividade pelo uso de diferentes inoculantes bacterianos quando estes foram comparados à testemunha com água. As curvas de progresso da doença com o uso de diferentes inoculantes bacterianos e a testemunha apresentaram valores de severidade próximos ao longo do tempo em todo o ciclo da cultura. Não houve diferença na intensidade do míldio e na produtividade de cebola com o uso de inoculantes bacterianos a base de Bacillus subtilis, B. amyloliquefaciens e B.pumilus; de Pseudomonas fluorescens e Azospirillum brasilense; e Azospirillum brasilense na cebola

Leaching of N derived from the soil and from [(15NH4) 2SO4] fertilizer during the growth cycle of bean plants

Em um solo Paleudal óxico (Terra Roxa Estruturada), no município de Piracicaba, SP, estudou-se a dinâmica do N-total e do N proveniente do fertilizante (sulfato de amônio - 15N) na solução do solo, para estimar as perdas de N por lixiviação, durante o desenvolvimento de uma cultura de feijão (Phaseolus vulgaris L.) 'Carioca', na época de outono (abril/julho). A cultura foi adubada com 42 kg/ha de N, usando sulfato de amônio altamente enriquecido em 15N (56,111% de átomos de 15N), aplicando-se o primeiro terço seis dias após a germinação (DAG), e o restante, 26 DAG. A solução do solo foi amostrada in situ, usando extratores instalados em triplicata, às profundidades de 45 cm, 75 cm, 105 cm e 135 cm do perfil. As amostras foram acumuladas em  estágios de 20 dias 0-6, 6-26, 26-46, 46-66 e 66-86 DAG), nas quais foram feitas as análises de N-total e de 15N, sendo este último para determinar a concentração (ppm) de nitrogênio proveniente do fertilizante, na solução do solo. Concluiu-se que: 1) durante o  desenvolvimento da cultura, a concentração média de N-total e a do N proveniente do fertilizante diminuíram marcadamente com a profundidade do solo, sendo que no limite inferior (105/135 cm), as concentrações de N-total (15 ppm) e a do N proveniente do fertilizante (0,048 ppm) foram muito baixas, e 2) durante o ciclo da cultura, sob as condições de mínima drenagem apenas 3 g/ha de N-total e 3,04 mg/ha de N-fertilizante foram lixiviados abaixo dos 120 cm de profundidade.In an Oxic Paleudalf ("Terra Roxa Estruturada") soil located in Piracicaba, São Paulo, the dynamics of soil total-N and N derived from fertilizer (ammonium sulphate - 15N) in the soil solution during a bean (Phaseolus vulgaris, L.) crop 'Carioca' growth in the Autumn period (April-July), was studied. Nitrogen losses due to leaching beyond 120cm of depth were estimated. The crop was fertilized with 42 kg/ha of N using ammonium sulphate, highly enriched with 15N (56,111% 15N atoms). The fertilization was made in two stages: 1/3 was applied six days after germination (DAG) and the rest 26 DAG. The soil solution was sampled in situ, using extractors placed in the following depths of profile: 45 cm, 75 cm, 105 cm and 135 cm. The samples were accumulated during each of five periods of 20 days (0-6, 6-2 26-46, 46-66 and 66-86 DAG). In these samples the total-nitrogen was determined, and percentage 15N atoms to determine the N derived from fertilizer. It was found that: 1) during the cropping period the average total-nitrogen concentration and N derived from fertilizer decreased markedly with soil depth, being very small (15 ppm and 0,048 ppm, respectively) at 105/135 cm of depth and, 2) during the crop development under minimal drainage conditions only 3 g/ha of total nitrogen and 3.04 mg/ha of N derived from fertilizer were leached beyond the 120 cm of depth

Geographic patterns of tree dispersal modes in Amazonia and their ecological correlates

Aim: To investigate the geographic patterns and ecological correlates in the geographic distribution of the most common tree dispersal modes in Amazonia (endozoochory, synzoochory, anemochory and hydrochory). We examined if the proportional abundance of these dispersal modes could be explained by the availability of dispersal agents (disperser-availability hypothesis) and/or the availability of resources for constructing zoochorous fruits (resource-availability hypothesis). Time period: Tree-inventory plots established between 1934 and 2019. Major taxa studied: Trees with a diameter at breast height (DBH) ≥ 9.55 cm. Location: Amazonia, here defined as the lowland rain forests of the Amazon River basin and the Guiana Shield. Methods: We assigned dispersal modes to a total of 5433 species and morphospecies within 1877 tree-inventory plots across terra-firme, seasonally flooded, and permanently flooded forests. We investigated geographic patterns in the proportional abundance of dispersal modes. We performed an abundance-weighted mean pairwise distance (MPD) test and fit generalized linear models (GLMs) to explain the geographic distribution of dispersal modes. Results: Anemochory was significantly, positively associated with mean annual wind speed, and hydrochory was significantly higher in flooded forests. Dispersal modes did not consistently show significant associations with the availability of resources for constructing zoochorous fruits. A lower dissimilarity in dispersal modes, resulting from a higher dominance of endozoochory, occurred in terra-firme forests (excluding podzols) compared to flooded forests. Main conclusions: The disperser-availability hypothesis was well supported for abiotic dispersal modes (anemochory and hydrochory). The availability of resources for constructing zoochorous fruits seems an unlikely explanation for the distribution of dispersal modes in Amazonia. The association between frugivores and the proportional abundance of zoochory requires further research, as tree recruitment not only depends on dispersal vectors but also on conditions that favour or limit seedling recruitment across forest types

Geography and ecology shape the phylogenetic composition of Amazonian tree communities

AimAmazonia hosts more tree species from numerous evolutionary lineages, both young and ancient, than any other biogeographic region. Previous studies have shown that tree lineages colonized multiple edaphic environments and dispersed widely across Amazonia, leading to a hypothesis, which we test, that lineages should not be strongly associated with either geographic regions or edaphic forest types.LocationAmazonia.TaxonAngiosperms (Magnoliids; Monocots; Eudicots).MethodsData for the abundance of 5082 tree species in 1989 plots were combined with a mega-phylogeny. We applied evolutionary ordination to assess how phylogenetic composition varies across Amazonia. We used variation partitioning and Moran's eigenvector maps (MEM) to test and quantify the separate and joint contributions of spatial and environmental variables to explain the phylogenetic composition of plots. We tested the indicator value of lineages for geographic regions and edaphic forest types and mapped associations onto the phylogeny.ResultsIn the terra firme and várzea forest types, the phylogenetic composition varies by geographic region, but the igapó and white-sand forest types retain a unique evolutionary signature regardless of region. Overall, we find that soil chemistry, climate and topography explain 24% of the variation in phylogenetic composition, with 79% of that variation being spatially structured (R2 = 19% overall for combined spatial/environmental effects). The phylogenetic composition also shows substantial spatial patterns not related to the environmental variables we quantified (R2 = 28%). A greater number of lineages were significant indicators of geographic regions than forest types.Main ConclusionNumerous tree lineages, including some ancient ones (>66 Ma), show strong associations with geographic regions and edaphic forest types of Amazonia. This shows that specialization in specific edaphic environments has played a long-standing role in the evolutionary assembly of Amazonian forests. Furthermore, many lineages, even those that have dispersed across Amazonia, dominate within a specific region, likely because of phylogenetically conserved niches for environmental conditions that are prevalent within regions

Geography and ecology shape the phylogenetic composition of Amazonian tree communities

Aim: Amazonia hosts more tree species from numerous evolutionary lineages, both young and ancient, than any other biogeographic region. Previous studies have shown that tree lineages colonized multiple edaphic environments and dispersed widely across Amazonia, leading to a hypothesis, which we test, that lineages should not be strongly associated with either geographic regions or edaphic forest types. Location: Amazonia. Taxon: Angiosperms (Magnoliids; Monocots; Eudicots). Methods: Data for the abundance of 5082 tree species in 1989 plots were combined with a mega-phylogeny. We applied evolutionary ordination to assess how phylogenetic composition varies across Amazonia. We used variation partitioning and Moran\u27s eigenvector maps (MEM) to test and quantify the separate and joint contributions of spatial and environmental variables to explain the phylogenetic composition of plots. We tested the indicator value of lineages for geographic regions and edaphic forest types and mapped associations onto the phylogeny. Results: In the terra firme and várzea forest types, the phylogenetic composition varies by geographic region, but the igapó and white-sand forest types retain a unique evolutionary signature regardless of region. Overall, we find that soil chemistry, climate and topography explain 24% of the variation in phylogenetic composition, with 79% of that variation being spatially structured (R$^{2}$ = 19% overall for combined spatial/environmental effects). The phylogenetic composition also shows substantial spatial patterns not related to the environmental variables we quantified (R$^{2}$ = 28%). A greater number of lineages were significant indicators of geographic regions than forest types. Main Conclusion: Numerous tree lineages, including some ancient ones (>66 Ma), show strong associations with geographic regions and edaphic forest types of Amazonia. This shows that specialization in specific edaphic environments has played a long-standing role in the evolutionary assembly of Amazonian forests. Furthermore, many lineages, even those that have dispersed across Amazonia, dominate within a specific region, likely because of phylogenetically conserved niches for environmental conditions that are prevalent within regions

Mapping density, diversity and species-richness of the Amazon tree flora

Using 2.046 botanically-inventoried tree plots across the largest tropical forest on Earth, we mapped tree species-diversity and tree species-richness at 0.1-degree resolution, and investigated drivers for diversity and richness. Using only location, stratified by forest type, as predictor, our spatial model, to the best of our knowledge, provides the most accurate map of tree diversity in Amazonia to date, explaining approximately 70% of the tree diversity and species-richness. Large soil-forest combinations determine a significant percentage of the variation in tree species-richness and tree alpha-diversity in Amazonian forest-plots. We suggest that the size and fragmentation of these systems drive their large-scale diversity patterns and hence local diversity. A model not using location but cumulative water deficit, tree density, and temperature seasonality explains 47% of the tree species-richness in the terra-firme forest in Amazonia. Over large areas across Amazonia, residuals of this relationship are small and poorly spatially structured, suggesting that much of the residual variation may be local. The Guyana Shield area has consistently negative residuals, showing that this area has lower tree species-richness than expected by our models. We provide extensive plot meta-data, including tree density, tree alpha-diversity and tree species-richness results and gridded maps at 0.1-degree resolution

Rarity of monodominance in hyperdiverse Amazonian forests.

Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics where a single tree species is dominant. Such "monodominant" forests are known from all of the main tropical regions. For Amazonia, we sampled the occurrence of monodominance in a massive, basin-wide database of forest-inventory plots from the Amazon Tree Diversity Network (ATDN). Utilizing a simple defining metric of at least half of the trees ≥ 10 cm diameter belonging to one species, we found only a few occurrences of monodominance in Amazonia, and the phenomenon was not significantly linked to previously hypothesized life history traits such wood density, seed mass, ectomycorrhizal associations, or Rhizobium nodulation. In our analysis, coppicing (the formation of sprouts at the base of the tree or on roots) was the only trait significantly linked to monodominance. While at specific locales coppicing or ectomycorrhizal associations may confer a considerable advantage to a tree species and lead to its monodominance, very few species have these traits. Mining of the ATDN dataset suggests that monodominance is quite rare in Amazonia, and may be linked primarily to edaphic factors