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.

Microbiological attributes of yellow oxissol under different monocultures in the savanna region of Piauí state / Atributos microbiológicos de um latossolos amarelo sob diferentes monoculturas no cerrado piauiense

Microbial biomass is an important component in maintaining soil quality and plant productivity. The aim of this paper was to evaluate alterations in microbiological attributes and organic carbon in accordance with seasonal change in different monocultures in the Savanna region of Piauí state. Soil samples were collected in areas of soy, eucalyptus, pasture, and in an area of native savanna, at depths of 0-0.20 m, during the rainy and dry periods. Using these samples microbial biomass carbon (MBC), basal respiration (BR), metabolic quotient (qCO2), microbial quotient (qMIC), and total organic carbon in the soil (TOC) were evaluated. MBC differed significantly between the systems evaluated, with higher values in the soil under native vegetation in the two sampling periods. TOC presented a significant difference between the systems, with higher values in the native savanna and soybean in the rainy period. For the qMIC, the soybean area presented lower values in the two periods compared with the other areas. Basal respiration as well as qCO2 values differed between the systems only in the dry period. The results reveal that the type of vegetation cover, management system, and seasonality influence the behavior of biological properties in the soil.

A biomassa microbiana é um componente importante para manter a qualidade do solo e a produtividade das plantas. O objetivo deste trabalho foi avaliar as alterações nos atributos microbiológicas e carbono orgânico, em função da variação sazonal em diferentes monoculturas no Cerrado piauiense. Amostras de solo foram coletadas em áreas de soja, eucalipto, pastagem e em uma área de mata nativa de Cerrado na profundidade de 0-0,20 m, durante o período chuvoso e seco. A partir dessas amostras avaliaram-se o carbono da biomassa microbiana (CBM), respiração basal (RB), quociente metabólico (qCO2), quociente microbiano (qMIC) e o carbono orgânico total do solo (COT). O CBM diferiu significativamente entre os sistemas avaliados, com maiores valores no solo sob mata nativa nos dois períodos de amostragem. O COT apresentou diferença significativa entre os sistemas, com maiores valores na mata nativa e soja no período chuvoso. Para o qMIC, a área com soja apresentou menores valores nos dois períodos em comparação às demais áreas. A RB assim como valores de qCO2 diferiram entre os sistemas apenas no período seco. Os resultados demonstram que o tipo de cobertura vegetal, o sistema de manejo e a sazonalidade influenciam o comportamento das propriedades biológicas do solo.

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.

Time-dependent effect of composted tannery sludge on the chemical and microbial properties of soil.

Composting has been suggested as an efficient method for tannery sludge recycling before its application to the soil. However, the application of composted tannery sludge (CTS) should be monitored to evaluate its effect on the chemical and microbial properties of soil. This study evaluated the time-dependent effect of CTS on the chemical and microbial properties of soil. CTS was applied at 0, 2.5, 5, 10, and 20 Mg ha-1 and the soil chemical and microbial properties were evaluated at 0, 45, 75, 150, and 180 days. Increased CTS rates increased the levels of Ca, Cr, and Mg. While Soil pH, organic C, and P increased with the CTS rates initially, this effect decreased over time. Soil microbial biomass, respiration, metabolic quotient, and dehydrogenase increased with the application of CTS, but decreased over time. Analysis of the Principal Response Curve showed a significant effect of CTS rate on the chemical and microbial properties of the soil over time. The weight of each variable indicated that all soil properties, except ß-glucosidase, dehydrogenase and microbial quotient, increased due to the CTS application. However, the highest weights were found for Cr, pH, Ca, P, phosphatase and total organic C. The application of CTS in the soil changed the chemical and microbial properties over time, indicating Cr, pH, Ca, phosphatase, and soil respiration as the more responsive chemical and microbial variables by CTS application.

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.

Fungal diversity in soils across a gradient of preserved Brazilian Cerrado.

The preserved Cerrado from Northeastern Brazil presents different physicochemical properties and plant diversity, which can influence the fungal communities. Therefore, we evaluated the fungal diversity in preserved sites, at Sete Cidades National Park, across a gradient of vegetation that included Campo graminoide, Cerrado stricto sensu, Cerradao, and Floresta decidual. Of all of the operational taxonomic units (OTUs) obtained, the Floresta decidual presented the highest richness. Ascomycota were the most abundant phylum (45%), followed by Basidiomycota (32%). Basal fungi and other phyla accounted for 23% of the total dataset. Agaricomycetes, Eurotiomycetes, Lecanoromycetes, Basidiobolus, Dothideomycetes, and Taphrinomycetes were the most abundant classes of fungi found across the gradient of Cerrado vegetation. In conclusion, our study suggests that the Brazilian Cerrado from Sete Cidades National Park presents a high fungal diversity and includes sources of new fungal species for biotechnological purposes.

Penetration resistance and density of a yellow oxissol under conventional management at different ages / Resistência a penetração e densidade de um latossolo amarelo sob manejo convencional em diferentes idades

Brazilian agriculture has been highlighted in Savanna areas due to significant gains in production and productivity in this biome. However, the production model with intensive use of machines for several years causes drastic changes in soil physical quality. This study aimed to investigate the influence of conventional management adoption time in a Yellow Oxissol on soil physical properties. Soil density, particle density, total porosity and soil resistance to penetration were assessed in areas under conventional management, in different usage times, in comparison to a native Savanna, which was used as control. The areas under conventional management contributed to increase the density and reduce the porosity, which was intensified with time of soil use. In the 6 years area, the porosity showed values below 0.50 m3 m-3 in the two measured layers. Higher penetration resistance values were observed to areas with higher use of time from 0.15 m depth, reaching values above 3.0 and 2.0 MPa in soils with 6 and 3 years of use, respectively, which is ranked as high. The native vegetation and the newly deforested area have provided less resistance to penetration along the profile, with values falling into low and moderate classes. Different time periods since the implementation of soil management were differentiated by the physical properties of studied soils.

A agricultura brasileira vem se destacando em áreas sob Cerrado devido aos ganhos significativos na produção e produtividade nesse bioma. No entanto, o modelo de produção com uso intensivo de máquinas por vários anos provoca alterações drásticas na qualidade física do solo. Neste trabalho, objetivou-se investigar o impacto do manejo convencional constante sobre os atributos físicos do solo. Foram avaliadas a densidade do solo, densidade de partículas, porosidade total e resistência do solo à penetração, em áreas sob manejo convencional em diferentes tempos de uso em relação a uma mata nativa de cerrado que foi usada como controle. As áreas sob manejo convencional contribuiu para aumentar a densidade e diminuir a porosidade que se intensificou com o tempo de uso do solo. Na área com 6 anos, a porosidade mostrou valores abaixo de 0,50 m3 m-3 nas duas camadas avaliadas. Observaram-se maiores valores de resistência à penetração para as áreas com maior tempo de uso a partir da profundidade 0,15 m, alcançando valores superiores a 3,0 e 2,0 MPa, nos solos com 6 e 3 anos de uso, respectivamente, classificado como alto. O cerrado nativo e a área recém-desmatada propiciaram menor resistência à penetração ao longo do perfil com valores classificados nas classes baixa e moderada. Períodos de tempo distintos desde a aplicação de manejos de solo foram diferenciados pelos atributos físicos do solo estudados.

Soil microbial properties after 5 years of consecutive amendment with composted tannery sludge.

Composting has been recognised an alternative method to tannery sludge recycling and afterwards to be used in agriculture. As the tannery sludge contains salts and chromium, the application of composted tannery sludge (CTS) should be performed carefully to minimise negative effects on soil microbial properties. Therefore, this study evaluated the effects of 5-year repeated CTS amendment on soil microbial biomass (SMB) and enzyme activities in a tropical soil. CTS was applied during 5 years at 0, 2.5, 5, 10 and 20 Mg ha(-1), and at the fifth year, the microbial biomass C (MBC) and N (MBN), basal and substrate-induced respiration (SIR), metabolic quotient (qCO2) and dehydrogenase (DHA) and fluorescein diacetate (FDA) hydrolysis were determined in the soil samples. Soil MBC and MBN showed the highest values with the amendment of 5 Mg ha(-1) CTS. Soil respiration increased with the increase in CTS rates, while SIR showed the highest values with the amendment of 0, 2.5 and 5 Mg ha(-1) CTS. DHA activity showed the highest values with the amendment up to 2.5 Mg ha(-1), while FDA hydrolysis increased up to the rate of 5 Mg ha(-1) CTS. The results show that after 5 years of permanent amendment of CTS, soils amended with 2.5 Mg ha(-1) have SMB and enzymatic activities similar to those in unamended soil.

Qualidade superficial de um solo sob sistemas de manejo utilizados para produção de forragens no estado do Piauí / Superficial soil quality under management systems for pasture in the state of Piaui, Brazil

Essa pesquisa objetivou avaliar o índice de qualidade do solo em sistemas de manejos sob pastagens e leguminosa em relação à mata secundária. Foram coletadas amostras de solo, na profundidade de 0 a 10 cm, nos seguintes ambientes: mata nativa dos Cocais sem qualquer exploração ou interferência antrópica; pastagem formada com capim-tanzânia e manejada no método de pastejo rotacionado com taxa de lotação fixa e, áreas com capim-tifton e povoamento de Leucena, manejadas para produção de feno. Todas as áreas foram implantadas no ano de 2000. Avaliaram-se o carbono orgânico, carbono da biomassa, indicadores químicos, físicos e biológicos de qualidade do solo. O carbono orgânico e da biomassa microbiana e o indicadores físicos não apresentaram diferenças entre os sistemas estudados. Os sistemas estudados e a mata apresentaram elevados quociente microbiano indicando matéria orgânica mais sujeita a transformações. A mata mostrou valores de diversidade de fauna superiores, em função da presença de serrapilheira com diversos tipos de substratos. O ordenamento dos ambientes para a qualidade de solo revelou que os sistemas estudados ficaram próximos ao ambiente de referência. O adequado manejo do capim Tifton e da Leucena para produção de feno e do capim Tanzânia em pastejo contribui para a manutenção das qualidades físicas, químicas e biológicas do solo em relação à mata nativa.

The aim of this paper was to evaluate the soil quality index under pastures and legumes systems. Soil samples were collected, at 0-10 cm depth, in the sites: native forest; pasture with Tifton grass; pasture with Tanzania grass under rotational grazing; Leucaena tress. We evaluated soil chemical, physical and biological properties. Soil organic C and microbial biomass did not show differences between the sites. Soil microbial quotient was higher under Tifton grass and native forest. The soil physical properties did not have significant differences. The native forest showed high values of soil fauna diversity, in function of the presence of a burlap with diverse types of substrates. The soil quality index allowed to infer on the changes imposed for agricultural practices, with respect to the soil physical, chemical and biological indicators.

Impacto do monocultivo de café sobre os indicadores biológicos do solo na zona da mata mineira / Impact of monocultivation coffee on biological indicators of quality soil in the zona da mata (MG), Brazil

Este estudo teve como objetivo avaliar o efeito do monocultivo de café em um latossolo, na Zona da Mata mineira, por meio de alterações em indicadores microbiológicos de qualidade do solo. Foram selecionadas quatro áreas: a) cultivo de café (Mundo Novo) durante 22 anos (C22), após uso com pastagem; b) cultivo de café (Catuaí) durante 16 anos (C16), antes mata secundária; c) mata secundária com aproximadamente de 30 anos (M30) e d) mata secundária com 40 anos (M40). Para tanto, amostras compostas de solos foram coletadas na profundidade de 0-10cm, em janeiro, abril, julho e outubro. As variáveis biológicas estudadas se mostraram sensíveis para caracterizar alterações de qualidade do solo decorrentes do monocultivo de café. Os resultados variaram com a estação do ano e o clima, e, no período mais seco, ocorreu uma redução nos valores, afetando mais drasticamente os sistemas com café. O índice de qualidade do solo demonstrou que o sistema C22 apresentou maior perda de qualidade em relação ao M40, indicando o comprometimento de sua sustentabilidade.

This study aimed to evaluate the effect of the coffee monoculture in an oxisol of the Zona da Mata (MG, Brazil) through changes in total organic carbon in the soil and microbiological indicators of soil quality. Four areas were selected: a) culture of coffee (Novo Mundo) during 22 years (C22); b) culture of coffee (Catuaí) during 16 years (C16) c) secondary forest with approximately 30 years old (M30) and d) secondary forest during 40 years (M40). Soil samples were collected in the depth of 0-10cm in January, April, July and October. The biological variables studied were sensitive to characterize changes in soil quality from coffee monoculture. The results varied with the season and climate. In the driest period, a reduction in the values occurred, affecting more drastically the coffee systems. The index of soil quality showed that the C22 system presented greater loss of quality in relation to the M40, indicating less sustainability commitment.