RESUMO

Lianas are major contributors to tropical forest dynamics, yet we know little about their mortality. Using overlapping censuses of the lianas and trees across a 50 ha stand of moist tropical forest, we contrasted community-wide patterns of liana mortality with relatively well-studied patterns of tree mortality to quantify patterns of liana death and identify contributing factors. Liana mortality rates were 172% higher than tree mortality rates, but species-level mortality rates of lianas were similar to trees with 'fast' life-history strategies and both growth forms exhibited similar spatial and size-dependent patterns. The mortality rates of liana saplings (<2.1 cm in diameter), which represent about 50% of liana individuals, decreased with increasing disturbance severity and remained consistently low during post-disturbance stand thinning. In contrast, larger liana individuals and trees of all sizes had elevated mortality rates in response to disturbance and their mortality rates decreased over time since disturbance. Within undisturbed forest patches, liana mortality rates increased with increasing soil fertility in a manner similar to trees. The distinct responses of liana saplings to disturbance appeared to distinguish liana mortality from that of trees, whereas similarities in their patterns of death suggest that there are common drivers of woody plant mortality.

Assuntos

RESUMO

Biochar obtained via microwave-assisted pyrolysis (MAP) at 720 W and 15 min from cocoa pod husk (CPH) is an efficient adsorbent of Cd2+(aq). Biochar of residual biomass of CPH (BCCPH) possesses favorable physicochemical and morphological properties, featuring a modest surface area yet a suitable porous structure. Adsorption, predominantly governed by physisorption, is influenced by the oxygen-containing active sites (-COOR, -C(R)O, and -CH2OR; R = H, alkyl). CdCO3 formation occurs during adsorption. Experimental data were well-fitted into various kinetic models for a broad understanding of the sorption process. Langmuir model indicates a maximum adsorption capacity of 14.694 mg/g. The thermodynamic study confirms the spontaneous and endothermic sorption. Studies at the molecular level have revealed that the Cd2+ ion tends to bind to surface aromatic carbon atoms. This sustainable approach produces BCCPH via MAP as a solution for waste transformation into water-cleaning materials.

RESUMO

Barium (Ba) is a non-essential element that can cause toxicity in living organisms and environmental contamination. Plants absorb barium predominantly in its divalent cationic form Ba2+. Sulfur (S) can decrease the availability of Ba2+ in the soil by causing its precipitation as barium sulfate, a compound known for its very low solubility. The objective of this study was to evaluate the effect of soil sulfate supply in soil Ba fractions, as well as on plant growth, and Ba and S uptake by lettuce plants grown in artificially Ba-contaminated soil under greenhouse conditions. The treatments consisted of five Ba doses (0, 150, 300, 450, and 600 mg kg-1 Ba, as barium chloride) combined with three S doses (0, 40, and 80 mg kg-1 S, as potassium sulfate). The treatments were applied to soil samples (2.5 kg) and placed in plastic pots for plant cultivation. The Ba fractions analyzed were extractable-Ba, organic matter-Ba, oxides associated-Ba, and residual-Ba. The results indicate that the extractable-Ba fraction was the main one responsible for Ba bioavailability and phytotoxicity, probably corresponding to the exchangeable Ba in the soil. The dose of 80 mg kg-1 of S reduced extractable-Ba by 30% at higher Ba doses while it increased the other fractions. Furthermore, S supply attenuated the growth inhibition in plants under Ba exposure. Thus, S supply protected the lettuce plants from Ba toxicity by reduction of Ba availability in soil and plant growth enhancement. The results suggest that sulfate supply is a suitable strategy for managing Ba-contaminated areas.

Assuntos

RESUMO

Recent research suggests that soybean yield could be doubled in Brazilian conditions, implying that the base fertilization is pivotal, as it might influence chemical and microbiological soil indicators and, hence, the crop grain yield. The current study had the goal of assessing alterations in the chemical and microbiological soil indicators, in the short term, as well as the soybean biometric and grain yield performance as a function of different fertilizers for base fertilization, in two sowing periods. An experiment comprised of two sowing periods was carried out in the 2019/2020 season on a dystrophic Red Latosol, in north Parana state. Five treatments were assessed, comprising: 1) control; 2) mineral fertilizer; 3) organomineral fertilizer; 4) mineral fertilizer mixed with granulated gypsum; and 5) slow release mineral fertilizer. A randomized block design with four replicates was adopted. The following variables were assessed: chemical and microbiological soil indicators; final stand; first pod insertion height; plant height; stem diameter; number of pods per plant; number of grains per plant; number of grains per pod; grain mass per plant; and one thousand grain mass and grain yield. There is no base fertilization effect on the chemical soil indicators in the short term, however, there is an effect on the microbiological soil indicators. Soybean biometric and grain yield performance is decreased with the delayed sowing period, regardless of the type of fertilizer utilized for base fertilization. Analyzing a set of soil quality indicators enables precise and judicious results to be gathered on management practices in the soil environment.(AU)

Pesquisas recentes apontam que a produtividade da soja pode ser duplicada em condições brasileiras, para tanto, a adubação de base se mostra fundamental, pois pode interferir nos indicadoresquímicos e microbiológicos do solo e, consequentemente, no rendimento da cultura. Assim, objetivou-se avaliar as alterações nos indicadoresquímicos e microbiológicosdo solo, no curto prazo, e o desempenhofitométrico e produtivo da soja em função do uso de diferentes fertilizantes na adubação de base, em duas épocas de semeadura. Foi conduzido experimento em duas épocas de semeadura na safra 2019/2020, em um Latossolo Vermelho distroférrico, no norte do estado do Paraná. Foram avaliados cincotratamentos que consistiram de: 1) controle; 2) fertilizante mineral; 3) fertilizante organomineral; 4) fertilizante mineral emmistura com gesso granulado e 5) fertilizante mineral de liberação lenta. O delineamento experimental foi em blocos ao acaso comquatro repetições. Foram avaliadososindicadoresquímicos e microbiológicos do solo; estande final; altura de inserção da primeira vagem; altura de planta; diâmetro do caule; número de vagens por planta; número de grãos por planta; número de grãos por vagem; massa de grãos por planta; massade mil grãos e produtividade. Não há efeito da adubação de base sobre os indicadoresquímicos do solo no curto prazo, porém, há efeito sobre os indicadoresmicrobiológicos. O desempenhofitométrico e produtivo da soja é reduzidoconforme o atraso da semeadura, independentemente do tipo de fertilizante utilizado na adubação de base.A análise conjunta de indicadores de qualidade do solo permite a obtenção de resultados precisos e criteriosos sobre as práticas de manejo no ambiente do solo.(AU)

Assuntos

RESUMO

BACKGROUND AND AIMS: We investigate patterns of evolution of genome size across a morphologically and ecologically diverse clade of Brassicaceae, in relation to ecological and life history traits. While numerous hypotheses have been put forward regarding autecological and environmental factors that could favour small vs. large genomes, a challenge in understanding genome size evolution in plants is that many hypothesized selective agents are intercorrelated. METHODS: We contribute genome size estimates for 47 species of Streptanthus Nutt. and close relatives, and take advantage of many data collections for this group to assemble data on climate, life history, soil affinity and composition, geographic range and plant secondary chemistry to identify simultaneous correlates of variation in genome size in an evolutionary framework. We assess models of evolution across clades and use phylogenetically informed analyses as well as model selection and information criteria approaches to identify variables that can best explain genome size variation in this clade. KEY RESULTS: We find differences in genome size and heterogeneity in its rate of evolution across subclades of Streptanthus and close relatives. We show that clade-wide genome size is positively associated with climate seasonality and glucosinolate compounds. Model selection and information criteria approaches identify a best model that includes temperature seasonality and fraction of aliphatic glucosinolates, suggesting a possible role for genome size in climatic adaptation or a role for biotic interactions in shaping the evolution of genome size. We find no evidence supporting hypotheses of life history, range size or soil nutrients as forces shaping genome size in this system. CONCLUSIONS: Our findings suggest climate seasonality and biotic interactions as potential forces shaping the evolution of genome size and highlight the importance of evaluating multiple factors in the context of phylogeny to understand the effect of possible selective agents on genome size.

Assuntos

RESUMO

Chemical and physical properties of soil can be altered with the successive application of liquid swine manure (LSM), also known as slurry. Therefore, monitoring the impact of LSM is essential to an assessment of the potential agronomic and environmental benefits and risks associated with management practices. The aim of this study was to evaluate the effects of LSM on the chemical and physical attributes of soil under pasture (Cynodon spp.), located in southern Brazil. Four areas were sampled: three areas cultivated with Cynodon spp. pasture with successive applications of 200 m3 ha1 y1 of LSM for three, eight and 15 years; and untreated native forest as a reference. The soil attributes evaluated were: organic carbon (OC), active (pH water) and potential acidity (H + Al+ 3), nutrient availability (i.e., P, K, Ca, Mg, Cu and Zn), soil bulk density, macro, micro and total porosity. Successive applications of LSM on pasture reduced soil active acidity, and increased the soil organic C and plant-available N, P, Ca, Mg, Cu and Zn contents. These effects were more intense with time and in the shallowest layers, i.e. 0-10 cm. Excessive increases in P, Cu and Zn in the soil should be carefully monitored to minimize the contamination risks to soil, ground and surface waters. Soil physical attribute changes were more associated with land use (pasture versus native forest) than LSM use, and LSM applications induced slight improvements in the soil structural quality over time.(AU)

Assuntos

RESUMO

The interaction of Zn with soil compartments influences its bioavailability and uptake by plants. In this study, rice and soybean were cultivated under greenhouse conditions with the aim of evaluating Zn bioavailability and fractionation in a clayey-textured Typic Hapludox as a function of Zn rates (4 or 8 mg kg 1 Zn). The experiment was conducted until grain filling. Two soil subsamples (t 1 and t 2 ) that referred to the seeding and flowering stages, were collected and compared with two single extraction schemes, DTPA (Zn DTPAt1 and Zn DTPAt2 ) and Mehlich-1 (Zn Mt1 and Zn Mt2 ) for Zn available contents. Zn fractionation was carried out with t 2 soil subsamples for the testing of the following fractions: exchangeable Zn (Zn Exc ), Zn bound to carbonates (Zn Carb ), Zn bound to organic matter (Zn OM ), Zn bound to oxides (Zn Oxi ) and residual Zn (Zn res ). Zn applied to soil increased the Zn concentration in labile fractions in decreasing order as follows: Zn Exc > Zn OM > Zn Carb . There was no difference between the lesser or unavailable fractions, Zn Oxi and Zn res, when there was no correlation between the rates either with total accumulated Zn in plants (Zna total ), or the contents extracted by DTPA or Mehlich-1. Total cumulative Zn content in rice and soybean affected by the ZnCl 2 rates applied were positively correlated with Zn content extracted by both solutions. Both extractant solutions presented positive correlation between available contents of Zn with Zn bound to labile fractions.(AU)

Assuntos

RESUMO

The interaction of Zn with soil compartments influences its bioavailability and uptake by plants. In this study, rice and soybean were cultivated under greenhouse conditions with the aim of evaluating Zn bioavailability and fractionation in a clayey-textured Typic Hapludox as a function of Zn rates (4 or 8 mg kg 1 Zn). The experiment was conducted until grain filling. Two soil subsamples (t 1 and t 2 ) that referred to the seeding and flowering stages, were collected and compared with two single extraction schemes, DTPA (Zn DTPAt1 and Zn DTPAt2 ) and Mehlich-1 (Zn Mt1 and Zn Mt2 ) for Zn available contents. Zn fractionation was carried out with t 2 soil subsamples for the testing of the following fractions: exchangeable Zn (Zn Exc ), Zn bound to carbonates (Zn Carb ), Zn bound to organic matter (Zn OM ), Zn bound to oxides (Zn Oxi ) and residual Zn (Zn res ). Zn applied to soil increased the Zn concentration in labile fractions in decreasing order as follows: Zn Exc > Zn OM > Zn Carb . There was no difference between the lesser or unavailable fractions, Zn Oxi and Zn res, when there was no correlation between the rates either with total accumulated Zn in plants (Zna total ), or the contents extracted by DTPA or Mehlich-1. Total cumulative Zn content in rice and soybean affected by the ZnCl 2 rates applied were positively correlated with Zn content extracted by both solutions. Both extractant solutions presented positive correlation between available contents of Zn with Zn bound to labile fractions.

Assuntos

RESUMO

Chemical and physical properties of soil can be altered with the successive application of liquid swine manure (LSM), also known as slurry. Therefore, monitoring the impact of LSM is essential to an assessment of the potential agronomic and environmental benefits and risks associated with management practices. The aim of this study was to evaluate the effects of LSM on the chemical and physical attributes of soil under pasture (Cynodon spp.), located in southern Brazil. Four areas were sampled: three areas cultivated with Cynodon spp. pasture with successive applications of 200 m3 ha1 y1 of LSM for three, eight and 15 years; and untreated native forest as a reference. The soil attributes evaluated were: organic carbon (OC), active (pH water) and potential acidity (H + Al+ 3), nutrient availability (i.e., P, K, Ca, Mg, Cu and Zn), soil bulk density, macro, micro and total porosity. Successive applications of LSM on pasture reduced soil active acidity, and increased the soil organic C and plant-available N, P, Ca, Mg, Cu and Zn contents. These effects were more intense with time and in the shallowest layers, i.e. 0-10 cm. Excessive increases in P, Cu and Zn in the soil should be carefully monitored to minimize the contamination risks to soil, ground and surface waters. Soil physical attribute changes were more associated with land use (pasture versus native forest) than LSM use, and LSM applications induced slight improvements in the soil structural quality over time.

Assuntos

RESUMO

Corn cultivation continually demands new technologies, since average yields can still be increased. This study aimed to evaluate the response of high-yield corn to humic acids, isolated from organic manure compost, with or without the application of lime and fertilizer. The experiment was conducted at Milhão® (http://www.omilhao.com.br) in Florestal, Minas Gerais State, Brazil. Three treatments were used: (a) control, without liming, fertilization, or humic acids; (b) conventional farm cultivation, with liming and fertilization; (c) liming, fertilization, and humic acids applied to seeds. The experiment design was a randomized block with five replicates (fifteen experimental units). Lime was applied at 1.6 Mg ha-1, incorporated into total area. Fertilization treatments included 300 kg ha-1 NPK 08-28-16 at sowing, and 500 kg ha-1 NPK 20-00-20 in coverage. The concentration of humic acids used in both seed treatment was 10 mmol L-1 of C. Biometrics and biomass productivity were evaluated at harvest time. Humic acids, whether applied as a seed coating, increased yield by ~15% higher than conventional farm cultivation, and this difference was statistically significant. Therefore, the use of humic acids based plant regulators is positive and complementary to the inputs generally used for corn yield.

O cultivo do milho demanda continuamente novas tecnologias, uma vez que a produtividade média pode ainda ser aumentada. O objetivo do presente trabalho foi avaliar a produtividade de milho verde em resposta à aplicação de ácidos húmicos isolados de composto orgânico de esterco bovino em condições de campo, na ausência e presença de calagem e adubação mineral, em lavoura alto rendimento. O experimento foi desenvolvido na área de produção da empresa O Milhão® (http://www.omilhao.com.br), em Florestal-MG. Foram esquematizados três tratamentos: (a) controle, sem calagem, fertilização e aplicação de ácidos húmicos; (b) cultivo convencional da fazenda, calagem e fertilização; (c) calagem, adubação e aplicação de ácidos húmicos nas sementes. O delineamento experimental foi o de blocos casualizados com cinco repetições (quinze unidades experimentais). Foram aplicados 1,6 Mg ha-1 de calcário, incorporados em área total. A adubação consistiu na aplicação de 300 kg ha-1 de NPK 08-28-16 no plantio e de 500 kg ha-1 de NPK 20-00-20 em cobertura. A concentração de ácidos húmicos usada no tratamento de sementes foi de 10 mmol L-1 de C. A biometria e a produtividade foram avaliadas no momento da colheita do milho. Os resultados mostraram efeitos significativos dos ácidos húmicos aplicados nas sementes, incrementando cerca de 15% a produtividade sobre o sistema convencional da fazenda. Assim, o uso de biorreguladores a base de ácidos húmicos é positivo e complementar frente aos insumos geralmente utilizados para a produção de milho.

Assuntos

RESUMO

Corn cultivation continually demands new technologies, since average yields can still be increased. This study aimed to evaluate the response of high-yield corn to humic acids, isolated from organic manure compost, with or without the application of lime and fertilizer. The experiment was conducted at Milhão® (http://www.omilhao.com.br) in Florestal, Minas Gerais State, Brazil. Three treatments were used: (a) control, without liming, fertilization, or humic acids; (b) conventional farm cultivation, with liming and fertilization; (c) liming, fertilization, and humic acids applied to seeds. The experiment design was a randomized block with five replicates (fifteen experimental units). Lime was applied at 1.6 Mg ha-1, incorporated into total area. Fertilization treatments included 300 kg ha-1 NPK 08-28-16 at sowing, and 500 kg ha-1 NPK 20-00-20 in coverage. The concentration of humic acids used in both seed treatment was 10 mmol L-1 of C. Biometrics and biomass productivity were evaluated at harvest time. Humic acids, whether applied as a seed coating, increased yield by ~15% higher than conventional farm cultivation, and this difference was statistically significant. Therefore, the use of humic acids based plant regulators is positive and complementary to the inputs generally used for corn yield.(AU)

O cultivo do milho demanda continuamente novas tecnologias, uma vez que a produtividade média pode ainda ser aumentada. O objetivo do presente trabalho foi avaliar a produtividade de milho verde em resposta à aplicação de ácidos húmicos isolados de composto orgânico de esterco bovino em condições de campo, na ausência e presença de calagem e adubação mineral, em lavoura alto rendimento. O experimento foi desenvolvido na área de produção da empresa O Milhão® (http://www.omilhao.com.br), em Florestal-MG. Foram esquematizados três tratamentos: (a) controle, sem calagem, fertilização e aplicação de ácidos húmicos; (b) cultivo convencional da fazenda, calagem e fertilização; (c) calagem, adubação e aplicação de ácidos húmicos nas sementes. O delineamento experimental foi o de blocos casualizados com cinco repetições (quinze unidades experimentais). Foram aplicados 1,6 Mg ha-1 de calcário, incorporados em área total. A adubação consistiu na aplicação de 300 kg ha-1 de NPK 08-28-16 no plantio e de 500 kg ha-1 de NPK 20-00-20 em cobertura. A concentração de ácidos húmicos usada no tratamento de sementes foi de 10 mmol L-1 de C. A biometria e a produtividade foram avaliadas no momento da colheita do milho. Os resultados mostraram efeitos significativos dos ácidos húmicos aplicados nas sementes, incrementando cerca de 15% a produtividade sobre o sistema convencional da fazenda. Assim, o uso de biorreguladores a base de ácidos húmicos é positivo e complementar frente aos insumos geralmente utilizados para a produção de milho.(AU)

Assuntos

RESUMO

BACKGROUND: pH is frequently reported as the main driver for prokaryotic community structure in soils. However, pH changes are also linked to "spillover effects" on other chemical parameters (e.g., availability of Al, Fe, Mn, Zn, and Cu) and plant growth, but these indirect effects on the microbial communities are rarely investigated. Usually, pH also co-varies with some confounding factors, such as land use, soil management (e.g., tillage and chemical inputs), plant cover, and/or edapho-climatic conditions. So, a more comprehensive analysis of the direct and indirect effects of pH brings a better understanding of the mechanisms driving prokaryotic (archaeal and bacterial) community structures. RESULTS: We evaluated an agricultural soil pH gradient (from 4 to 6, the typical range for tropical farms), in a liming gradient with confounding factors minimized, investigating relationships between prokaryotic communities (16S rRNA) and physical-chemical parameters (indirect effects). Correlations, hierarchical modeling of species communities (HMSC), and random forest (RF) modeling indicated that both direct and indirect effects of the pH gradient affected the prokaryotic communities. Some OTUs were more affected by the pH changes (e.g., some Actinobacteria), while others were more affected by the indirect pH effects (e.g., some Proteobacteria). HMSC detected a phylogenetic signal related to the effects. Both HMSC and RF indicated that the main indirect effect was the pH changes on the availability of some elements (e.g., Al, Fe, and Cu), and secondarily, effects on plant growth and nutrient cycling also affected the OTUs. Additionally, we found that some of the OTUs that responded to pH also correlated with CO2, CH4, and N2O greenhouse gas fluxes. CONCLUSIONS: Our results indicate that there are two distinct pH-related mechanisms driving prokaryotic community structures, the direct effect and "spillover effects" of pH (indirect effects). Moreover, the indirect effects are highly relevant for some OTUs and consequently for the community structure; therefore, it is a mechanism that should be further investigated in microbial ecology.

Assuntos

RESUMO

Root-lesion nematode (RLN (Pratylenchus brachyurus) is an important challenge to soybean production in Central Brazil due to its widespread occurrence, along with the absence of resistant cultivars and strategies for its management. The aim of this research was to evaluate the relationship among soil properties, RLN populations, and soybean crop growth using geostatistical analysis. The experiment was conducted in a soybean field located in the northern half of Mato Grosso state, in Brazil, with a history of damages by RLN. The results suggest a positive correlation between plant height and values of pH, Ca, Mg, and base saturation. On the other hand, RLN population was positively correlated with organic carbon, cation exchange capacity, and soil potential acidity. Moreover, our findings also indicate that soybean plant growth is reduced under acidic soil conditions, as susceptibility to RLN increases. Thus, the correction of soil acidity to suitable levels for soybean crop becomes an important strategy to minimize damages by RLN.

O nematoide das lesões radiculares (NLR) (Pratylenchus brachyurus) representa um importante desafio para a produção de soja na região central do Brasil, devido a sua ocorrência generalizada e à ausência de cultivares resistentes e de estratégias adequadas para o seu manejo. O objetivo deste trabalho foi estudar as relações entre atributos de solo, a população de NLR e o crescimento de plantas de soja, usando ferramentas de geoestatística. O estudo foi realizado em área de produção comercial de soja na região do médio norte do Estado de Mato Grosso, com histórico de danos causados pelo NLR. Os resultados indicam que há correlação negativa entre a intensidade dos sintomas causados pela infestação do NLR e alguns atributos químicos do solo, tais como pH, Ca, Mg e saturação por bases. A população do NLR é positivamente correlacionada ao carbono orgânico, a capacidade de troca de cátions e a acidez potencial do solo. Há evidências de que a acidez do solo aumenta a suscetibilidade das plantas de soja ao ataque do NLR. Nesse sentido, a correção da acidez do solo para níveis adequados à cultura da soja é uma importante estratégia para minimizar os danos causados pelo NLR.

Assuntos

RESUMO

Root-lesion nematode (RLN (Pratylenchus brachyurus) is an important challenge to soybean production in Central Brazil due to its widespread occurrence, along with the absence of resistant cultivars and strategies for its management. The aim of this research was to evaluate the relationship among soil properties, RLN populations, and soybean crop growth using geostatistical analysis. The experiment was conducted in a soybean field located in the northern half of Mato Grosso state, in Brazil, with a history of damages by RLN. The results suggest a positive correlation between plant height and values of pH, Ca, Mg, and base saturation. On the other hand, RLN population was positively correlated with organic carbon, cation exchange capacity, and soil potential acidity. Moreover, our findings also indicate that soybean plant growth is reduced under acidic soil conditions, as susceptibility to RLN increases. Thus, the correction of soil acidity to suitable levels for soybean crop becomes an important strategy to minimize damages by RLN.(AU)

O nematoide das lesões radiculares (NLR) (Pratylenchus brachyurus) representa um importante desafio para a produção de soja na região central do Brasil, devido a sua ocorrência generalizada e à ausência de cultivares resistentes e de estratégias adequadas para o seu manejo. O objetivo deste trabalho foi estudar as relações entre atributos de solo, a população de NLR e o crescimento de plantas de soja, usando ferramentas de geoestatística. O estudo foi realizado em área de produção comercial de soja na região do médio norte do Estado de Mato Grosso, com histórico de danos causados pelo NLR. Os resultados indicam que há correlação negativa entre a intensidade dos sintomas causados pela infestação do NLR e alguns atributos químicos do solo, tais como pH, Ca, Mg e saturação por bases. A população do NLR é positivamente correlacionada ao carbono orgânico, a capacidade de troca de cátions e a acidez potencial do solo. Há evidências de que a acidez do solo aumenta a suscetibilidade das plantas de soja ao ataque do NLR. Nesse sentido, a correção da acidez do solo para níveis adequados à cultura da soja é uma importante estratégia para minimizar os danos causados pelo NLR.(AU)

Assuntos

RESUMO

A demanda crescente da utilização dos solos exige soluções que permitam incentivar o desenvolvimento socioeconômico sem comprometer a sustentabilidade dos recursos naturais. Desse modo, o objetivo deste estudo foi avaliar os efeitos de diferentes culturas como café, pastagem e manejo integrado de pastagem e eucalipto na qualidade química e microbiológica do solo. Foram analisados da parte química o pH do solo, nitrogênio, carbono orgânico total e fósforo do solo e da parte microbiológica foram analisados a densidade de esporos de fungos micorrizicos arbusculares (FMAs), carbono da biomassa microbiana (CBM), respiração basal do solo e coeficiente metabólico do solo qCO2. O pH do solo variou de 5,38 no manejo de pasto e eucalipto para 4,70 nas áreas cultivadas com pasto. A densidades de esporos de FMAs e o CBM na área de integração de pasto e eucalipto foram aumentados em relação à área cultivada com café, e o qCO2 foi aumentado com o cultivo do café, indicando que o cultivo de café eleva a condição de estresse do solo nas condições avaliadas. Concluindo, portanto, que as diferentes formas de uso e manejo das três áreas estudadas apontaram variações do comportamento de suas propriedades químicas e microbiológicas, entretanto, o manejo que se destacou foi a de eucalipto com a integração de pastagens, sendo mais sustentável.(AU)

The increasing demand for land use requires solutions that encourage its socio-economic development without compromising the sustainability of natural resources. The purpose of this study was to evaluate the effects of different crops such as coffee, pasture and the integrated management of pasture and eucalyptus in the chemical and microbiological quality of the soil. Chemical tests were performed to obtain the pH, nitrogen, total organic carbon, and phosphorus contents on the land, while microbiological parameters analyzed the density of arbuscular mycorrhizal fungi (AMF) spores, microbial biomass carbon (MBC), soil basal respiration (SBR) and soil metabolic coefficient qCO2. The soil pH varied from 5.38 in the management of pasture and eucalyptus to 4.70 in the areas cultivated with only pasture. The density of AMF spores and the MBC were higher in the pasture and eucalyptus integration when compared with coffee cultivation; the qCO2 in soil with coffee was higher than that found for the integration of pasture and eucalyptus. Those results indicate that coffee cultivated in those conditions increase stress in the soil due to higher SBR. It can be concluded that the different forms of use and management of the three studied areas show variations in the behavior of the chemical and microbiological properties in the soil, and eucalyptus with pasture integration presents a better sustainable soil management.(AU)

La demanda creciente de utilización del suelo exige soluciones que permitan incentivar el desarrollo socioeconómico sin comprometer la sustentabilidad de los recursos naturales. Así, el objetivo de ese estudio ha sido evaluar los efectos de diferentes culturas como café, pastaje y manejo integrado de pastaje y eucalipto en la calidad química y microbiológica del suelo. Se analizaron de la parte química, el pH del suelo, nitrógeno, carbono orgánico total y fosforo del suelo, y de la parte microbiológica se analizaron la densidad de esporos de fungos micorrizicos arbusculares (FMAs), carbono de la biomasa microbiana (CBM), respiración basal del suelo y coeficiente metabólico del suelo qCO2. El pH del suelo osciló de 5,38 en el manejo de pasto y eucalipto para 4,70 las áreas cultivadas con pasto. La densidad de esporos de FMAs y el CBM en el área de integración de pasto y eucalipto han aumentado en relación al área cultivada con café, y el qCO2 fue aumentado con el cultivo de café, indicando que el cultivo de café eleva la condición de estrés del suelo en las condiciones evaluadas. Concluyendo, por lo tanto, que las diferentes formas de uso y manejo de las tres áreas estudiadas, apuntaron variaciones de comportamiento de sus propiedades químicas y microbiológicas, entretanto el manejo que se destacó fue la del eucalipto con la integración de pastajes, siendo más sostenible.(AU)

Assuntos

RESUMO

A demanda crescente da utilização dos solos exige soluções que permitam incentivar o desenvolvimento socioeconômico sem comprometer a sustentabilidade dos recursos naturais. Desse modo, o objetivo deste estudo foi avaliar os efeitos de diferentes culturas como café, pastagem e manejo integrado de pastagem e eucalipto na qualidade química e microbiológica do solo. Foram analisados da parte química o pH do solo, nitrogênio, carbono orgânico total e fósforo do solo e da parte microbiológica foram analisados a densidade de esporos de fungos micorrizicos arbusculares (FMAs), carbono da biomassa microbiana (CBM), respiração basal do solo e coeficiente metabólico do solo qCO2. O pH do solo variou de 5,38 no manejo de pasto e eucalipto para 4,70 nas áreas cultivadas com pasto. A densidades de esporos de FMAs e o CBM na área de integração de pasto e eucalipto foram aumentados em relação à área cultivada com café, e o qCO2 foi aumentado com o cultivo do café, indicando que o cultivo de café eleva a condição de estresse do solo nas condições avaliadas. Concluindo, portanto, que as diferentes formas de uso e manejo das três áreas estudadas apontaram variações do comportamento de suas propriedades químicas e microbiológicas, entretanto, o manejo que se destacou foi a de eucalipto com a integração de pastagens, sendo mais sustentável.(AU)

The increasing demand for land use requires solutions that encourage its socio-economic development without compromising the sustainability of natural resources. The purpose of this study was to evaluate the effects of different crops such as coffee, pasture and the integrated management of pasture and eucalyptus in the chemical and microbiological quality of the soil. Chemical tests were performed to obtain the pH, nitrogen, total organic carbon, and phosphorus contents on the land, while microbiological parameters analyzed the density of arbuscular mycorrhizal fungi (AMF) spores, microbial biomass carbon (MBC), soil basal respiration (SBR) and soil metabolic coefficient qCO2. The soil pH varied from 5.38 in the management of pasture and eucalyptus to 4.70 in the areas cultivated with only pasture. The density of AMF spores and the MBC were higher in the pasture and eucalyptus integration when compared with coffee cultivation; the qCO2 in soil with coffee was higher than that found for the integration of pasture and eucalyptus. Those results indicate that coffee cultivated in those conditions increase stress in the soil due to higher SBR. It can be concluded that the different forms of use and management of the three studied areas show variations in the behavior of the chemical and microbiological properties in the soil, and eucalyptus with pasture integration presents a better sustainable soil management.(AU)

La demanda creciente de utilización del suelo exige soluciones que permitan incentivar el desarrollo socioeconómico sin comprometer la sustentabilidad de los recursos naturales. Así, el objetivo de ese estudio ha sido evaluar los efectos de diferentes culturas como café, pastaje y manejo integrado de pastaje y eucalipto en la calidad química y microbiológica del suelo. Se analizaron de la parte química, el pH del suelo, nitrógeno, carbono orgánico total y fosforo del suelo, y de la parte microbiológica se analizaron la densidad de esporos de fungos micorrizicos arbusculares (FMAs), carbono de la biomasa microbiana (CBM), respiración basal del suelo y coeficiente metabólico del suelo qCO2. El pH del suelo osciló de 5,38 en el manejo de pasto y eucalipto para 4,70 las áreas cultivadas con pasto. La densidad de esporos de FMAs y el CBM en el área de integración de pasto y eucalipto han aumentado en relación al área cultivada con café, y el qCO2 fue aumentado con el cultivo de café, indicando que el cultivo de café eleva la condición de estrés del suelo en las condiciones evaluadas. Concluyendo, por lo tanto, que las diferentes formas de uso y manejo de las tres áreas estudiadas, apuntaron variaciones de comportamiento de sus propiedades químicas y microbiológicas, entretanto el manejo que se destacó fue la del eucalipto con la integración de pastajes, siendo más sostenible.(AU)

Assuntos

RESUMO

The role of chemical and mineralogical soil properties in the retention and oxidation of atmospheric mercury in tropical soils is discussed based on thermal desorption analysis. The retention of gaseous mercury by tropical soils varied greatly both quantitatively and qualitatively with soil type. The average natural mercury content of soils was 0.08 ± 0.06 µg g(-1) with a maximum of 0.215 ± 0.009 µg g(-1). After gaseous Hg(0) incubation experiments, mercury content of investigated soils ranged from 0.6 ± 0.2 to 735 ± 23 µg g(-1), with a mean value of 44 ± 146 µg g(-1). Comparatively, A horizon of almost all soil types adsorbed more mercury than B horizon from the same soil, which demonstrates the key role of organic matter in mercury adsorption. In addition to organic matter, pH and CEC also appear to be important soil characteristics for the adsorption of mercury. All thermograms showed Hg(2+) peaks, which were predominant in most of them, indicating that elemental mercury oxidized in tropical soils. After four months of incubation, the thermograms showed oxidation levels from 70% to 100%. As none of the samples presented only the Hg(0) peak, and the soils retained varying amounts of mercury despite exposure under the same incubation conditions, it became clear that oxidation occurred on soil surface. Organic matter seemed to play a key role in mercury oxidation through complexation/stabilization of the oxidized forms. The lower percentages of available mercury (extracted with KNO3) in A horizons when compared to B horizons support this idea.

Assuntos

RESUMO

Corn is grown throughout the country, with its yields varying according to the technology investment. Among the technologies that seek to optimize productivity, the focus is on the use of improved seeds, which is associated with the properly integrated management of production factors such as pH adjustment and soil fertilization, irrigation, pest control and competitors, and more recently, the use of plant growth regulators. Analogous to synthetic growth regulators such as auxins, humic substances in organic matter have a stimulating effect on plants. However, the bioactivity and optimum concentration of humic substances vary with the type of plant and the type of raw materials used for their isolation. This work aimed to study the growth and development of maize in response to the treatment of seeds by different concentrations of humic acids. The treatments involved the application of two sources of humic acid (bovine manure and poultry litter) and five concentrations (0, 10, 20, 30, and 40 mmol L-1 of C) of humic acid solutions to seeds in a bioassay carried out in a greenhouse. At the end of the experiment (45 days after germination), plants were evaluated biometrically and nutritionally. The results showed a significant increase in the growth and development of shoots and roots, and there was a significant accumulation of N and P after the application of humic acid isolated from bovine manure. These effects did not occur with the application of humic acid isolated from poultry litter. Therefore, biostimulation by humic acids isolated from bovine manure showed positive results and was complementary as compared to the effects of other inputs commonly used in the treatment of maize seeds.(AU)

O milho é cultivado em todo o país, produzindo quantidades variáveis conforme o investimento em tecnologia. Dentre essas tecnologias, destaca-se o uso de sementes melhoradas, associadas com adequado manejo integrado dos fatores de produção, tais como a correção e fertilização dos solos, a irrigação, o controle fitossanitário e de competidores e, mais recentemente, o uso de biorreguladores, buscando otimizar a produtividade. De forma análoga aos reguladores de crescimento sintéticos, como as auxinas, as substâncias húmicas da matéria orgânica apresentam um efeito estimulante em plantas. Contudo, a bioatividade e a concentração ótima das substâncias húmicas variam de acordo com as espécies vegetais e com matérias primas das quais elas foram isoladas. Por essas razões, este trabalho teve como objetivo estudar o crescimento e desenvolvimento do milho, em resposta à aplicação de diferentes concentrações de ácidos húmicos, via tratamento de sementes. Os tratamentos constituíramse de duas fontes de ácidos húmicos (esterco bovino e cama de aviário) utilizando cinco concentrações (0, 10, 20, 30 e 40 mmol L-1 de C) das respectivas soluções, aplicado via tratamentos de sementes em um bioensaio conduzido em casa de vegetação. Ao final do experimento (45 dias após a germinação), as plantas foram avaliadas biometricamente e nutricionalmente. Os resultados mostraram incrementos  significativos no crescimento e desenvolvimento da parte aérea e do sistema radicular, e acumulosignificativo dos nutrientes N e P com a aplicação de ácidos húmicos isolados de esterco bovino, sendo que os mesmos não ocorreram com a aplicação de ácidos húmicos isolados de cama de aviário. Assim o uso de bioestimulantes à base de ácidos húmicos isolados de esterco bovino é positivo e complementarcomparativamente aos insumos geralmente usados no tratamento de sementes de milho.(AU)

Assuntos

RESUMO

Corn is grown throughout the country, with its yields varying according to the technology investment. Among the technologies that seek to optimize productivity, the focus is on the use of improved seeds, which is associated with the properly integrated management of production factors such as pH adjustment and soil fertilization, irrigation, pest control and competitors, and more recently, the use of plant growth regulators. Analogous to synthetic growth regulators such as auxins, humic substances in organic matter have a stimulating effect on plants. However, the bioactivity and optimum concentration of humic substances vary with the type of plant and the type of raw materials used for their isolation. This work aimed to study the growth and development of maize in response to the treatment of seeds by different concentrations of humic acids. The treatments involved the application of two sources of humic acid (bovine manure and poultry litter) and five concentrations (0, 10, 20, 30, and 40 mmol L-1 of C) of humic acid solutions to seeds in a bioassay carried out in a greenhouse. At the end of the experiment (45 days after germination), plants were evaluated biometrically and nutritionally. The results showed a significant increase in the growth and development of shoots and roots, and there was a significant accumulation of N and P after the application of humic acid isolated from bovine manure. These effects did not occur with the application of humic acid isolated from poultry litter. Therefore, biostimulation by humic acids isolated from bovine manure showed positive results and was complementary as compared to the effects of other inputs commonly used in the treatment of maize seeds.

O milho é cultivado em todo o país, produzindo quantidades variáveis conforme o investimento em tecnologia. Dentre essas tecnologias, destaca-se o uso de sementes melhoradas, associadas com adequado manejo integrado dos fatores de produção, tais como a correção e fertilização dos solos, a irrigação, o controle fitossanitário e de competidores e, mais recentemente, o uso de biorreguladores, buscando otimizar a produtividade. De forma análoga aos reguladores de crescimento sintéticos, como as auxinas, as substâncias húmicas da matéria orgânica apresentam um efeito estimulante em plantas. Contudo, a bioatividade e a concentração ótima das substâncias húmicas variam de acordo com as espécies vegetais e com matérias primas das quais elas foram isoladas. Por essas razões, este trabalho teve como objetivo estudar o crescimento e desenvolvimento do milho, em resposta à aplicação de diferentes concentrações de ácidos húmicos, via tratamento de sementes. Os tratamentos constituíramse de duas fontes de ácidos húmicos (esterco bovino e cama de aviário) utilizando cinco concentrações (0, 10, 20, 30 e 40 mmol L-1 de C) das respectivas soluções, aplicado via tratamentos de sementes em um bioensaio conduzido em casa de vegetação. Ao final do experimento (45 dias após a germinação), as plantas foram avaliadas biometricamente e nutricionalmente. Os resultados mostraram incrementos  significativos no crescimento e desenvolvimento da parte aérea e do sistema radicular, e acumulosignificativo dos nutrientes N e P com a aplicação de ácidos húmicos isolados de esterco bovino, sendo que os mesmos não ocorreram com a aplicação de ácidos húmicos isolados de cama de aviário. Assim o uso de bioestimulantes à base de ácidos húmicos isolados de esterco bovino é positivo e complementarcomparativamente aos insumos geralmente usados no tratamento de sementes de milho.

Assuntos

RESUMO

This study was conducted to evaluate the effect of liquid waste of bovine slaughter (RLF) on the chemical characteristics of a Entisol under pasture grass Marandu. We applied four levels of RLF (0, 37.5, 75, 112.5 m³ ha-1). The experimental design was randomized blocks. The soil samples were collected at 0-10, 10-20, 20-30, 30-40 cm, deep five replicates, which were analyzed in pH, available P and K+, Ca2+, Mg2+ and Al3+, CTCpH7,0, CTCeffective, organic matter content and potential acidity (H+ Al3+). We calculated the saturation of exchangeable bases (V%) and aluminum (m%). The applications of RLF in doses of 75 and 112.5 m³ ha-1 reduced the pH and level of Al3+. We observed increased of the value the V% at 0-10 cm and CTCeffective in 10-20 cm. The organic matter content had no significant increases for the implementation of RLF. The Mg2+ increased in the 30-40 cm layer at 112.5 m³ ha-1. The results suggest that application of 37.5 m³ ha-1 increases the pH and Ca2+ and K+ at a depth of 0-10 cm and the value of CTCpH7,0 to 30 cm. The pH, total bases, CTC, CTCpH 7,0 , saturation on base, K+, Ca2+, Mg2+ were influenced by the depth with higher values in the 0-10 cm depth compared with other in all the treatments.

Este experimento foi realizado com o objetivo de avaliar o efeito da aplicação de resíduo líquido de frigorífico (RLF) sobre as características químicas de um Neossolo Quartzarênico Órtico típico sob pastagem de capim-Marandu. Foram aplicadas quatro doses de RLF (0; 37,5; 75; 112,5 m³ ha- 1). O delineamento experimental utilizado foi em blocos inteiramente casualizados. Foram coletadas amostras de solo nas profundidades de 0-10, 10-20, 20-30, 30-40 cm, em cinco repetições, nas quais foram analisados pH, P e K+ disponíveis, Ca2+, Mg2+ e Al3+ trocáveis, CTCpH7,0, CTCefetiva, teores de matéria orgânica e acidez potencial (H+Al) após 90 dias da aplicação do resíduo líquido. Foi calculada a saturação por bases trocáveis (V%) e por alumínio (m%). A aplicação de RLF nas doses de 75 e 112,5 m³ ha-1 reduziram o pH e os teores de Al3+ e aumentaram a V% na camada de 0-10 cm e a CTCefetiva na camada de 10-20 cm. Os teores de matéria orgânica não foram influenciados pela aplicação do RLF. Os teores de Mg2+ aumentaram na camada 30-40 cm na dose de 112,5 m³ ha-1. Os resultados evidenciam que a aplicação de 37,5 m³ ha-1 aumentou o pH e os teores de Ca2+ e K+ na profundidade de 0-10 cm e o valor da CTCpH7,0 de 0 a 30 cm. O pH, soma de bases, CTC efetiva, CTC pH 7, saturação por bases, K+, Ca2+, Mg2+ foram influenciados pela profundidade com maiores valores na camada de 0-10 cm em relação às dem