Arbuscular mycorrhizal fungi community in soils under desertification and restoration in the Brazilian semiarid.

Soil desertification has a significant social, economic, and environmental impact worldwide. Mycorrhizal diversity remains poorly understood in semiarid regions impacted by desertification, especially in Brazilian drylands. More importantly, positive impacts of grazing exclusion on mycorrhizal communities are still incipient. Here, we hypothesized that overgrazing changes the structure of Arbuscular Mycorrhizal Fungi (AMF) community compared to native areas and, grazing exclusion is effective to restore the AMF community. Thus, we analyzed the status of AMF community in soils under desertification (overgrazing) and restoration (twenty-years of grazing exclusion) in the Brazilian semiarid. AMF-spores were extracted via humid decantation methodology, morphologically classified, and alpha diversity metrics were calculated. Soil samples were chemically, and physically characterized and multivariate statistical analyses were applied to verify the impact of soil degradation and restoration on AMF-community. Briefly, native, and restored areas presented higher contents of organic matter, phosphorus, microbial carbon, and ß-glucosidase activity. However, degraded soil showed higher Al3+, Na+, and bulk soil density values. The abundance of AMF spores was higher in restored soil, followed by degraded and native vegetation, and Shannon's diversity index was significantly higher in restored soils, followed by native vegetation. AMF-spores were classified into four families (Gigasporaceae > Acaulosporaceae > Glomeraceae > Ambisporaceae). Ambisporaceae was closed correlated with degraded soil, mainly with Al3+, Na+, and bulk soil density properties. On the other hand, Acaulosporaceae and Glomeraceae were positively correlated with native vegetation and restored soil, respectively, thereby improving Shannon index, richness, enzyme activity, and soil respiration. Thus, grazing exclusion, in long term, can be a good strategy to restore AMF-diversity in soils in the Brazilian semiarid.

Isolation and Characterization of Plant Growth-Promotion Diazotrophic Endophytic Bacteria Associated to Sugarcane (Saccharum officinarum L.) Grown in Paraíba, Brazil

Abstract: Sugarcane is an important Brazilian commodity, being usually cultivated in soils with low natural fertility. This study aimed to isolate diazotrophic endophytes from sugarcane tissues and evaluate the morphological and physiological characteristics of their colonies as well as their plant growth-promoting (PGP) traits in select diazotrophic endophytic bacteria. Fifty-six bacterial isolates were identified in the sugarcane tissues, and these isolates presented distinct morphological and physiological traits. A total of thirty-five bacterial isolates were biochemically evaluated. Overall, Bacillus was the dominant genus. Isolates of Methylobacterium spp. and Brevibacillus agri were present only in leaves, while Herbaspirillum seropedicae occurred only in stems. Except to IPA-CF45A, all isolates were nitrogenase positive. All endophytes exhibit production of indol 3-acetic acid. Over 50% of endophytes solubilize phosphate, release N-acyl homoserine lactones, and present the activity of 1-aminocyclopropane-1-carboxylic acid deaminase, catalase, lipase and protease. The network analysis showed that isolates belonged to Burkholderia, Herbaspirillum, and Methylobacterium interact with Bacillus. Bacterial endophytes exhibited distinct morphological, physiological, and PGP traits that are useful for sustainable agriculture, highlighting the isolates IPA-CC33, IPA-CF65, IPA-CC9 and IPA-CF27. Further studies on the effects of these diazotrophic endophytes and their potential for providing microbial inoculants for improving sugarcane fields will provide valuable information to maintain the sustainability and environment quality.

Genetic diversity and structure in natural populations of Cajui from Brazilian Cerrado

Cajui (Anacardium spp.) is a native fruit tree (small cashew) of the Brazilian Cerrado and possesses the potential for commercialization. However, cajui exploitation occurs exclusively through extractivism in the absence of conservation strategies. The lack of conservation strategies may lead to a decrease in genetic diversity of Anacardium. In this work, the genetic diversity and population structure of three natural populations in Sete Cidades National Park (PNSC; PI, Brazil) were assessed using ISSR analysis of 56 cajui accessions and two A. occidentale accessions (outgroup) from Pacajus (CE, Brazil). A total of 112 markers were obtained, 93 (83.04%) of which were polymorphic. The diversity indices of these populations indicated moderate levels of genetic diversity. According to AMOVA, 96.17% of the genetic variability lay within populations, with low genetic differentiation among populations (ΦST = 0.03828). Furthermore, STRUCTURE analysis indicated the existence of four connected genetic groups. The findings show that the individuals from the three collection sites did not represent different subpopulations, likely due to the high gene flow (Nm = 6.7) favored by the floral biology of Anacardium, pollinators and small-animal seed dispersers. This research identifies genetically divergent individuals (C-03, C-05, C-22, C-26, C-34 and C-39), which should be considered priority individuals for conservation and can inform conservation programs for Anacardium spp.

Inoculation of arbuscular mycorrhizal fungi as a strategy to improve annatto (Bixa orellana L. ) growth

This study aimed to assess the occurrence of arbuscular mycorrhizal fungi (AMF) in annatto (Bixa orellana L.) cultivars and their response to AMF inoculation using biometric parameters. The occurrence surveys were conducted in annatto fields in three municipalities from Pernambuco Forest Zone: Lagoa de Itaenga, Gloria de Goitá, and Vitoria de Santo Antão, and in four cultivars (Red Piave, Green Piave, Red Peruvian Paulista, and Green Peruvian Paulista). In a greenhouse, biometric parameters of annatto seedlings of Red Piave, Red Peruvian Paulista, Embrapa-36, and Embrapa-37 cultivars inoculated with AMF isolated from annatto fields. The Red Piave cultivar exhibited greater root colonization than the Green Peruvian Paulista in the Lagoa de Itaenga and Vitoria de Santo Antão municipalities. The cultivar Red Piave showed a more beneficial association with AMF in plants and soil than cultivar Green Peruvian Paulista did, in both Lagoa de Itaenga and Vitoria de Santo Antão. AMF inoculation was effective in promoting the growth of annatto plants, particularly those inoculants with S. heterogama and C. etunicatum.(AU)

Seed size influences the promoting activity of rhizobia on plant growth, nodulation and N fixation in lima bean / O tamanho da semente influencia a atividade promotora dos rizóbios sobre o crescimento de plantas, nodulação e fixação de N em feijão-fava

This study evaluated the activity of rhizobia isolates inoculated in large (18 mm) and small (11 mm) seeds on lima bean growth, nodulation and N fixation. Selected rhizobia isolates were compared with a reference strain CIAT899 and two controls without inoculation. Large seeds contributed for highest plant growth, nodulation and N fixation than small seeds. The isolates UFPI-59, UFPI-18 and UFPI-38 promoted the highest values of shoot and root dry weight, respectively. The isolates UFPI-32 promoted the highest values of nodule number, while UFPI-59 promoted the highest values of nodule dry weight. The isolates UFPI-38 and UFPI-59 promoted the highest accumulation of N. This study showed that seed size really influences lima bean growth, nodulation and BNF. Considering rhizobia isolates, UFPI-59, UFPI-38, and UFPI-18 contributed for plant growth, promoted better nodulation and effectiveness on biological N fixation.(AU)

Este estudo avaliou a atividade de isolados de rizóbios inoculados em sementes pequenas (11 mm) e grandes (18 mm) sobre o crescimento, nodulação e fixação de N de feijão-fava. Isolados selecionados de rizóbios foram comparados com uma estirpe de referência CIAT899 e dois controles sem inoculação. Sementes grandes contribuíram para maior crescimento de plantas, nodulação e fixação de N do que sementes pequenas. Os isolados UFPI-59, UFPI-18 e UFPI-38 promoveram os maiores valores de massa seca de parte aérea e raízes. Os isolados UFPI-32 e UFPI-59 promoveram os maiores valores de número e massa de nódulos, respectivamente. Os isolados UFPI-38 e UFPI-59 promoveram maior acúmulo de N. Este estudo mostrou que o tamanho de sementes influencia o crescimento, nodulação e fixação de N em feijão-fava. Considerando os isolados de rizóbios, UFPI-59, UFPI-38 e UFPI-18 contribuíram para o crescimento de plantas, promoveram melhor nodulação e eficiência na fixação de N.(AU)

Inoculation of arbuscular mycorrhizal fungi as a strategy to improve annatto (Bixa orellana L. ) growth

This study aimed to assess the occurrence of arbuscular mycorrhizal fungi (AMF) in annatto (Bixa orellana L.) cultivars and their response to AMF inoculation using biometric parameters. The occurrence surveys were conducted in annatto fields in three municipalities from Pernambuco Forest Zone: Lagoa de Itaenga, Gloria de Goitá, and Vitoria de Santo Antão, and in four cultivars (Red Piave, Green Piave, Red Peruvian Paulista, and Green Peruvian Paulista). In a greenhouse, biometric parameters of annatto seedlings of Red Piave, Red Peruvian Paulista, Embrapa-36, and Embrapa-37 cultivars inoculated with AMF isolated from annatto fields. The Red Piave cultivar exhibited greater root colonization than the Green Peruvian Paulista in the Lagoa de Itaenga and Vitoria de Santo Antão municipalities. The cultivar Red Piave showed a more beneficial association with AMF in plants and soil than cultivar Green Peruvian Paulista did, in both Lagoa de Itaenga and Vitoria de Santo Antão. AMF inoculation was effective in promoting the growth of annatto plants, particularly those inoculants with S. heterogama and C. etunicatum.

Nodulation, nitrogen uptake and growth of lima bean in a composted tannery sludge-treated soil / Nodulação, absorção de nitrogênio e crescimento de feijão-fava em solo tratado com lodo de curtume compostado

This study evaluated the responses of lima bean (Phaseolus lunatus L.) to application of composted tannery sludge on nodulation, N uptake and plant growth. For eight years, the compost was applied at rates of: 0, 2.5, 5, 10, and 20 Mg ha-1 (dry basis). Plants of lima bean showed higher nodulation in treatments with compost; however, nodules reported in these treatments presented lower biomass, size and diversity than those reported in treatment without compost. Accumulation of N increased with the application of the highest rate (20 Mg ha-1), while there was an increase in chromium content in shoot with the increase in compost rates. Thus, the use of composted tannery sludge, in long-term, increases the accumulation of chromium in plants, increasing nodulation, while decrease rhizobia diversity in nodules.(AU)

Este estudo avaliou a resposta do feijão-fava (Phaseolus lunatus L.) a aplicação de lodo de curtume compostado na nodulação, absorção de N e crescimento. Durante oito anos, o composto foi aplicado em doses de: 0, 2.5, 5, 10, e 20 Mg ha-1 (base seca). As plantas de feijão-fava mostraram maior nodulação nos tratamentos com o composto. Entretanto, os nódulos encontrados nestes tratamentos apresentaram menor biomassa, tamanho e diversidade do que os observados no tratamento sem composto. A acumulação de N aumentou com a aplicação da maior dose do composto (20 Mg ha-1), enquanto que houve um aumento nos teores de crômio na parte aérea com o aumento das doses do composto. Desta forma, o uso do lodo de curtume compostado, em longo prazo, aumenta a acumulação de crômio, aumentando a nodulação, enquanto diminui a diversidade de rizóbios nos nódulos.(AU)

Nodulation, nitrogen uptake and growth of lima bean in a composted tannery sludge-treated soil / Nodulação, absorção de nitrogênio e crescimento de feijão-fava em solo tratado com lodo de curtume compostado

This study evaluated the responses of lima bean (Phaseolus lunatus L.) to application of composted tannery sludge on nodulation, N uptake and plant growth. For eight years, the compost was applied at rates of: 0, 2.5, 5, 10, and 20 Mg ha-1 (dry basis). Plants of lima bean showed higher nodulation in treatments with compost; however, nodules reported in these treatments presented lower biomass, size and diversity than those reported in treatment without compost. Accumulation of N increased with the application of the highest rate (20 Mg ha-1), while there was an increase in chromium content in shoot with the increase in compost rates. Thus, the use of composted tannery sludge, in long-term, increases the accumulation of chromium in plants, increasing nodulation, while decrease rhizobia diversity in nodules.

Este estudo avaliou a resposta do feijão-fava (Phaseolus lunatus L.) a aplicação de lodo de curtume compostado na nodulação, absorção de N e crescimento. Durante oito anos, o composto foi aplicado em doses de: 0, 2.5, 5, 10, e 20 Mg ha-1 (base seca). As plantas de feijão-fava mostraram maior nodulação nos tratamentos com o composto. Entretanto, os nódulos encontrados nestes tratamentos apresentaram menor biomassa, tamanho e diversidade do que os observados no tratamento sem composto. A acumulação de N aumentou com a aplicação da maior dose do composto (20 Mg ha-1), enquanto que houve um aumento nos teores de crômio na parte aérea com o aumento das doses do composto. Desta forma, o uso do lodo de curtume compostado, em longo prazo, aumenta a acumulação de crômio, aumentando a nodulação, enquanto diminui a diversidade de rizóbios nos nódulos.

Archaea diversity in vegetation gradients from the Brazilian Cerrado

We used 16S rRNA sequencing to assess the archaeal communities across a gradient of Cerrado. The archaeal communities differed across the gradient. Crenarcheota was the most abundant phyla, with Nitrosphaerales and NRPJ as the predominant classes. Euryachaeota was also found across the Cerrado gradient, including the classes Metanocellales and Methanomassiliicoccaceae.(AU)

Archaea diversity in vegetation gradients from the Brazilian Cerrado

Abstract We used 16S rRNA sequencing to assess the archaeal communities across a gradient of Cerrado. The archaeal communities differed across the gradient. Crenarcheota was the most abundant phyla, with Nitrosphaerales and NRPJ as the predominant classes. Euryachaeota was also found across the Cerrado gradient, including the classes Metanocellales and Methanomassiliicoccaceae.

Less abundant bacterial groups are more affected than the most abundant groups in composted tannery sludge-treated soil.

The application of composted tannery sludge (CTS) has promoted shifts in soil chemical properties and, therefore, can affect the soil bacterial community. This study assessed the effect of the CTS on the soil bacterial community over time. The CTS was applied at five rates (0, 2.5, 5, 10 and 20 t/ha), and the bacterial community was evaluated for 180 days. The principal curve response (PRC) analysis showed that the most abundant phyla were not influenced by the CTS rates over time, while the analysis of the bacterial community showed that some of the less abundant phyla were influenced by the CTS rates. Similarly, the PRC analysis for the bacterial classes showed the significant effect of the CTS rates. The redundancy analyses for the bacterial phyla and classes showed the relationship between the significant chemical properties and the bacterial community of the soil after the CTS amendment over time. Therefore, there was a shift in the bacterial community over time with the application of the composted tannery sludge. Our study has shown that the less abundant bacterial groups were more influenced by the CTS than the most abundant bacterial groups and that these bacterial groups were driven by soil chemical properties, primarily chromium (Cr) and the soil pH.

Archaea diversity in vegetation gradients from the Brazilian Cerrado.

We used 16S rRNA sequencing to assess the archaeal communities across a gradient of Cerrado. The archaeal communities differed across the gradient. Crenarcheota was the most abundant phyla, with Nitrosphaerales and NRPJ as the predominant classes. Euryachaeota was also found across the Cerrado gradient, including the classes Metanocellales and Methanomassiliicoccaceae.

Bacillus subtilis improves maize tolerance to salinity / Bacillus subtilis melhora a tolerância do milho a salinidade

ABSTRACT: The aim of this study was to evaluate the biochemical responses of maize, under saline stress, inoculated with Bacillus subtilis. Four levels of salinity were assessed: 0mM, 50mM, 100mM, and 200mM of sodium chloride (NaCl). Saline conditions influenced negatively maize growth. However, the inoculation of B. subtilis improved the plant growth at highest level of NaCl. Chlorophyll content decreased while proline increased in inoculated plants submitted to highest salt levels. Also, B. subtilis increased the relative water content in leaves. B. subtilis improves the plant growth under salinity and ameliorates the biochemical damages in maize.

RESUMO: O objetivo do estudo foi avaliar a resposta bioquímica do milho, sob stresse salino, inoculado com Bacillus subtilis. Quatro níveis de salinidade foram avaliados: 0mM, 50mM, 100mM e 200mM de cloreto de sódio (NaCl). Condições salinas influenciaram negativamente o crescimento do milho. Entretanto, a inoculação com B. subtilis melhorou o crescimento das plantas no maior nível de NaCl. O teor de clorofila decresceu enquanto que a prolina aumentou em plantas submetidas aos níveis salinos e inoculadas com B. subtilis. B. subtilis também aumentou o conteúdo de agua foliar. A inoculação com B. subtilis promove melhor crescimento das plantas sob salinidade e atenua os danos bioquímicos no milho.

Bacillus subtilis improves maize tolerance to salinity

ABSTRACT: The aim of this study was to evaluate the biochemical responses of maize, under saline stress, inoculated with Bacillus subtilis. Four levels of salinity were assessed: 0mM, 50mM, 100mM, and 200mM of sodium chloride (NaCl). Saline conditions influenced negatively maize growth. However, the inoculation of B. subtilis improved the plant growth at highest level of NaCl. Chlorophyll content decreased while proline increased in inoculated plants submitted to highest salt levels. Also, B. subtilis increased the relative water content in leaves. B. subtilis improves the plant growth under salinity and ameliorates the biochemical damages in maize.

RESUMO: O objetivo do estudo foi avaliar a resposta bioquímica do milho, sob stresse salino, inoculado com Bacillus subtilis. Quatro níveis de salinidade foram avaliados: 0mM, 50mM, 100mM e 200mM de cloreto de sódio (NaCl). Condições salinas influenciaram negativamente o crescimento do milho. Entretanto, a inoculação com B. subtilis melhorou o crescimento das plantas no maior nível de NaCl. O teor de clorofila decresceu enquanto que a prolina aumentou em plantas submetidas aos níveis salinos e inoculadas com B. subtilis. B. subtilis também aumentou o conteúdo de agua foliar. A inoculação com B. subtilis promove melhor crescimento das plantas sob salinidade e atenua os danos bioquímicos no milho.

Bacillus subtilis improves maize tolerance to salinity / Bacillus subtilis melhora a tolerância do milho a salinidade

The aim of this study was to evaluate the biochemical responses of maize, under saline stress, inoculated with Bacillus subtilis. Four levels of salinity were assessed: 0mM, 50mM, 100mM, and 200mM of sodium chloride (NaCl). Saline conditions influenced negatively maize growth. However, the inoculation of B. subtilis improved the plant growth at highest level of NaCl. Chlorophyll content decreased while proline increased in inoculated plants submitted to highest salt levels. Also, B. subtilis increased the relative water content in leaves. B. subtilis improves the plant growth under salinity and ameliorates the biochemical damages in maize.(AU)

O objetivo do estudo foi avaliar a resposta bioquímica do milho, sob stresse salino, inoculado com Bacillus subtilis. Quatro níveis de salinidade foram avaliados: 0mM, 50mM, 100mM e 200mM de cloreto de sódio (NaCl). Condições salinas influenciaram negativamente o crescimento do milho. Entretanto, a inoculação com B. subtilis melhorou o crescimento das plantas no maior nível de NaCl. O teor de clorofila decresceu enquanto que a prolina aumentou em plantas submetidas aos níveis salinos e inoculadas com B. subtilis. B. subtilis também aumentou o conteúdo de agua foliar. A inoculação com B. subtilis promove melhor crescimento das plantas sob salinidade e atenua os danos bioquímicos no milho.(AU)

Chemical and microbiological indicators of quality in a yellow oxissol under conventional tillage of different ages / Indicadores microbiológicos e químicos de qualidade de um latossolo amarelo sob manejo convencional em diferentes idades

Brazil's agricultural production in Savanna soils has been highlighted due to significant yield gains in these areas. The present study aimed to evaluate changes in soil chemical and biological indicators of Piauí Savanna areas after 1 (PC1), 3 (PC3) and 6 (PC6) years under conventional tillage compared to a native Savanna forest (NF), used as control. Chemical (pH, P, Ca2+, Mg2+, K+, H+, Al3+ and organic carbon) and total organic carbon (TOC) and microbiological attributes (microbial biomass carbon (MBC), basal respiration, microbial quotient and metabolic quotient), were assessed. In PC6 and PC3 areas, Al³+, H+ + Al3+ and total organic carbon reduction and pH and nutrient content increase were observed in all layers evaluated. TOC was little influenced by time, since the change was gradual according to soil use. MBC and qMIC values were higher in the soil under natural vegetation, indicating adverse effects of monoculture managed with prolonged conventional tillage on these variables. PC6 soil had the highest qCO2 values in the depths of 0 to 0.20 and 0.20 to 0.40 m, which shows low efficiency of microorganisms in converting organic residue into microbial biomass in this system. Conventional management increased soil biological quality loss and favored chemical properties with its time of use.

A produção agrícola brasileira vem se destacando nos solos sob Cerrado devido aos ganhos significantes na produção e produtividade nessas áreas. Neste trabalho, objetivou-se avaliar as alterações nos indicadores químicos e biológicos do solo em áreas de Cerrado piauiense com 1 (PC1), 3 (PC3) e 6 (PC6) anos manejadas sob plantio convencional, em relação a uma mata nativa (MN) de Cerrado usada como controle. Foram avaliados atributos químicos (pH, P, Ca2+, Mg2+, K+, H+, Al3+ e carbono orgânico) e microbiológicos (carbono da biomassa microbiana, respiração basal, quociente microbiano e quociente metabólico). Nas áreas PC6 e PC3 foram observados, em todas as camadas avaliadas, redução dos teores de Al³+ e H+ + Al3+ e carbono orgânico total, e aumento do pH e teores dos nutrientes em relação aos demais sistemas. O COT mostrou-se pouco sensível com o tempo, visto que a mudança foi gradual conforme o uso do solo. Os valores de CBM e qMIC foram mais elevados no solo sob vegetação natural, indicando a ocorrência de efeitos adversos de monocultura manejada em sistema plantio convencional prolongado sobre essas variáveis. O solo sob PC6 mostrou o maiores valores de qCO2 nas profundidades de 0 a 0,20 e de 0,20 a 0,40 m que demonstra a baixa eficiência dos microrganismos em converter os resíduos orgânicos em biomassa microbiana neste sistema. O manejo convencional utilizado potencializou a perda de qualidade biológica do solo desses sistemas e favoreceu os atributos químicos com o tempo de uso.

Resposta do milho verde à inoculação com Azospirillum brasilense e níveis de nitrogênio / Response of green corn to Azospirillum brasilense inoculation and N levels

O objetivo deste trabalho foi avaliar o efeito da inoculação com Azospirillum brasilense e adubação nitrogenada sobre a produtividade do milho verde. O estudo foi conduzido no município de Teresina, PI, em 2011 e 2012, e os tratamentos foram dispostos em delineamento de blocos ao acaso sob arranjo fatorial de 5x2, sendo cinco doses de nitrogênio (N) (0, 50, 100, 150 e 200 kg N ha-1) com e sem inoculação. No tratamento com inoculação, foi utilizado um produto formulado contendo A. brasilense, estirpes Abv5 e Abv6. Houve aumento significativo no número e na massa das espigas comerciais com a inoculação de A. brasilense em relação ao tratamento sem inoculação. A combinação de inoculação com A. brasilence e nitrogênio aumenta em mais de 30% a produção de espigas de milho verde.(AU)

The aim of this study was to evaluate the effect of A. brasilense inoculation and nitrogen fertilization on green corn yield. The study was conducted out in Teresina, PI, in 2011 and 2012, and treatments were arranged in a randomized block design with five N rates (0, 50, 100, 150 and 200 kg N ha-1) with and without inoculation. In the inoculated treatment it was used a product with A. brasilense, strains Abv5 and Abv6. There was a significant increase in both number and mass of commercial corn cobs with A. brasilense inoculation as compared with treatment without inoculation. The association of inoculation with A. brasilence and nitrogen increase more than 30% the corn cobs production.(AU)

Resposta do milho verde à inoculação com Azospirillum brasilense e níveis de nitrogênio / Response of green corn to Azospirillum brasilense inoculation and N levels

O objetivo deste trabalho foi avaliar o efeito da inoculação com Azospirillum brasilense e adubação nitrogenada sobre a produtividade do milho verde. O estudo foi conduzido no município de Teresina, PI, em 2011 e 2012, e os tratamentos foram dispostos em delineamento de blocos ao acaso sob arranjo fatorial de 5x2, sendo cinco doses de nitrogênio (N) (0, 50, 100, 150 e 200 kg N ha-1) com e sem inoculação. No tratamento com inoculação, foi utilizado um produto formulado contendo A. brasilense, estirpes Abv5 e Abv6. Houve aumento significativo no número e na massa das espigas comerciais com a inoculação de A. brasilense em relação ao tratamento sem inoculação. A combinação de inoculação com A. brasilence e nitrogênio aumenta em mais de 30% a produção de espigas de milho verde.

The aim of this study was to evaluate the effect of A. brasilense inoculation and nitrogen fertilization on green corn yield. The study was conducted out in Teresina, PI, in 2011 and 2012, and treatments were arranged in a randomized block design with five N rates (0, 50, 100, 150 and 200 kg N ha-1) with and without inoculation. In the inoculated treatment it was used a product with A. brasilense, strains Abv5 and Abv6. There was a significant increase in both number and mass of commercial corn cobs with A. brasilense inoculation as compared with treatment without inoculation. The association of inoculation with A. brasilence and nitrogen increase more than 30% the corn cobs production.

Emergência e crescimento inicial de plântulas de pimenta ornamental e celosia em substrato à base de composto de lodo de curtume / Germination and initial growth of ornamental Capsicum and Celosia in substrate of composted tannery sludge

Há grande potencial de uso dos resíduos industriais compostados como substrato na produção de mudas de espécies ornamentais. O objetivo deste trabalho foi avaliar a emergência e o crescimento inicial de plântulas de pimenta ornamental e celosia em substratos à base de composto de lodo de curtume. O experimento foi instalado em bandejas de isopor e os substratos utilizados foram: composto de lodo de curtume; composto de lodo de curtume + 10 por cento de vermiculita; composto de lodo de curtume + 20 por cento de vermiculita; substrato comercial à base de turfa, usado como controle. No composto de lodo de curtume, houve aumento na velocidade de emergência das plântulas apenas para pimenta ornamental. Para a fitomassa, a altura das plantas e para o comprimento das raízes, os maiores valores ocorreram nos tratamentos em que o substrato foi o composto de lodo de curtume, em relação à turfa. O maior valor de fitomassa das raízes foi obtido quando o substrato foi o composto de lodo de curtume associado com 10 por cento de vermiculita. O composto de lodo de curtume é uma alternativa potencial para uso como substrato na produção de mudas de pimenta ornamental e celosia.

For composted industrial wastes have high potential to use as substrate for seedling production of ornamental species, therefore that the aim of this work was to evaluate emergency and plant growth of ornamental Capsicum and Celosia in substrate based of tannery sludge compost. The experiment was carried out in trays and substrates were: tannery sludge compost, tannery sludge compost + 10 percent vermiculite, tannery sludge compost + 20 percent vermiculite, commercial substrate used as control. In the tannery sludge compost there was an increase in the rate of seedling emergence only for ornamental pepper. For the plant biomass, height and root length the highest values occurred in treatments where the substrate was tannery sludge compost as compared as with commercial substrate. The higher value of root biomass was obtained when the substrate was tannery sludge composted associated with 10 percent vermiculite. The tannery sludge compost may be a potential alternative for use as substrate in seedling production of ornamental Capsicum and celosia.

Soil microbial biomass in organic farming system / Biomassa microbiana do solo em sistemas orgânicos

Agricultural production systems have to combine management practices in order to sustain soil's profitability and quality. Organic farming is gaining worldwide acceptance and has been expanding at an annual rate of 20 percent in the last decade, accounting for over 24 million hectares worldwide. Organic practices avoid applications of synthetic fertilizers and pesticides, rely on organic inputs and recycling for nutrient supply, and emphasize cropping system design and biological processes for pest management, as defined by organic farming regulation in the world. In comparison with conventional farming, organic farming has potential benefits in improving food quality and safety. Plant production in organic farming mainly depends on nutrient release as a function of mineralization processes in soils. The build-up of a large and active soil microbial biomass is important pool of accessible nutrients, therefore, is an important priority in organic farming. In organic farming, there is positive effect of quantity and quality of inputs of organic residues on soil microbial biomass. In this way, the organic systems are extremely important for the increase of the soil fertility and the maintenance of the environmental sustainability.

A produção agrícola tem de combinar práticas para prover a sustentabilidade do solo. A agricultura orgânica está ganhando aceitação mundial e cresce à taxa anual de 20 por cento na última década, contabilizando mais de 24 milhões de hectares. As práticas orgânicas evitam o uso de fertilizantes sintéticos e pesticidas, enfatiza a aplicação de matéria orgânica, como também a reciclagem de nutrientes e de processos biológicos para manejo de pragas, através das regras dos sistemas orgânicos no mundo. Em comparação com a agricultura convencional, os sistemas orgânicos têm potencial de melhorar a qualidade e a segurança dos alimentos. A produção das plantas no sistema orgânico depende da liberação de nutrientes pelo processo de mineralização microbiana no solo. A construção de uma grande e ativa biomassa microbiana é um importante reservatório de nutrientes disponíveis. Dessa forma, isso é uma prioridade no sistema orgânico. Em sistemas orgânicos, há efeitos positivos da quantidade e da qualidade das fontes de carbono orgânico sobre a biomassa microbiana do solo. Nesse sentido, as práticas do sistema orgânico são extremamente importantes para o aumento da fertilidade do solo e para a manutenção da sustentabilidade ambiental.