Abstract Background Diversified crop systems provide several advantages for crop production and the agricultural ecosystem. In contrast, growing the same crop for consecutive years increases weeds, insects, and diseases issues, adding further cost to crop production owing to their management. Objective The objective was to evaluate the effects of six different winter cover crops and compare the impacts of a diversified rotation system in contrast to the succession system, combined with three different post-emergence herbicide management looking up to soybean yield, aboveground mass production, and weed density impact. Methods The experiment was performed over 2014 to 2018, using a randomized block design with four replications. Cover crop treatments were 1) fallow 2) wheat 3) rye 4) rye + turnip 5) rye + vetch 6) black oats. At the time of cover crop termination, weed density was counted and aboveground mass was measured. The crop rotation system was an alternated soybean and corn using three different post-emergence herbicide treatments, and the succession system was soybean each year. When a significant effect was observed after test F, the Tukey test (p ≤ 0.05) was applied to compare treatment effects. Results Rye + vetch as a cover crop, rotation system, and herbicide usage showed a higher impact on weed density. Rye + turnip has produced more aboveground biomass. Soybean yield was higher after wheat. Conclusions Cover crops implementation, crop rotation system, and herbicide usage have increased biomass production and crop yield, and reduced weed density showing integrated weed management as a key strategy for production systems.

ABSTRACT This study aimed to analyze Resolution CNE/CP 2/2019 - which defines the current National Curriculum Guidelines for the initial teacher training and sets the Common National Base (BNC-Training) - in order to identify and discuss the implications of proposed changes in valuing teaching work. This was a qualitative study, in which data were collected through literature and documentary analysis, systematized and analyzed through two categories: Relationship teacher training - professional ethos; Professional appreciation and engagement. The results demonstrate the alignment of the new resolution with the neoliberal prescription, limiting training to technical and pragmatic aspects adjusted to an economistic perspective. This resolution clearly expresses a standardization of policies for teacher training focused on skills in order to meet the assumptions of the BNCC. Also, the present logic neglects professional development as a collective project and becomes associated with meritocratic criteria of individual performance related to liberal ideas. Finally, we consider the need to build an active/collective resistance, both at the pedagogical and political levels, against the precarity and privatization of higher education.

RESUMO Este estudo apresenta os resultados de uma pesquisa que teve por objetivo analisar a Resolução CNE/CP n.º 2/2019 - que define as atuais Diretrizes Curriculares Nacionais para a formação inicial de professores e institui a Base Nacional Comum (BNC-Formação) - de modo a identificar e discutir as implicações das mudanças propostas na valorização do trabalho docente. Trata-se de uma pesquisa qualitativa na qual os dados foram coletados por meio de análise bibliográfica e documental, sistematizados e analisados por meio de duas categorias: Relação formação docente - ethos profissional; Valorização e engajamento profissional. Os resultados demonstram o alinhamento da nova resolução com o receituário neoliberal, limitando essa formação a aspectos técnicos e pragmáticos ajustados a uma perspectiva economicista. Fica explícito que essa resolução expressa uma padronização das políticas para a formação docente centrada em competências de modo a atender aos pressupostos da Base Nacional Comum Curricular (BNCC). Entendemos também que a lógica na qual está baseada negligencia a valorização profissional como um projeto coletivo e passa a ser associada a critérios meritocráticos de desempenho individual ligados ao ideário liberal. Por fim, consideramos a necessidade de construção de uma resistência ativa/coletiva, tanto no plano pedagógico como no plano político, contra a precarização e a privatização do Ensino Superior.

ABSTRACT Methane (CH4) is the second major greenhouse gas after CO2, exerting a significant influence on the climate and the chemistry of the atmosphere. In lowland soil, acetate and H2/CO2 are the most important precursors of CH4 and formed from organic matter fermentation in an anaerobic environment, giving rise to short-chain organic acids (ethanoic, propanoic, and butanoic), depending on the type of crop residue and the soil management system. Ethanoic acid can be directly converted to CH4 by methanogenic microorganisms, but propanoic and butanoic acids must be converted to acetate before being converted to CH4. This study aimed to quantify, in isolation, the dynamics and CH4 emission potential of the three short-chain organic acids found in flooded lowland soils with rice crops. The study was carried out in a controlled environment using four standard carbon doses (0, 90, 180, and 270 mg kg−1) of ethanoic, propanoic, and butanoic acids. The dynamics and the potential emission of CH4 from soil were investigated when the acids were applied to flooded soil previously incubated for 20 days. The CH4 emission dynamics were altered with the application of the three short-chain organic acids to the soil, even using an equal amount of carbon. The faster and more intense emission was achieved with the ethanoic acid application in relation to the other two acids application, while butanoic acid presents slower, delayed, and prolonged dynamics of CH4 emission. Propanoic acid resulted in the lowest CH4 emission due to its own stoichiometry and the temperature condition in which the experiment was conducted, which were unfavorable to the hydrogenotrophic bacteria. The addition of short-chain organic acids promoted a priming effect in the soil with conversion values of C to CH4 above the calculated theoretical values.

RESUMO: O Rio Grande do Sul possui cerca de 20% da área total de solos de terras baixas, propícias para o cultivo do arroz (Oryza sativa) irrigado por inundação. Buscando mitigar danos ocasionados com o monocultivo de arroz, novas culturas, como o sorgo (Sorghum bicolor) e a soja (Glycine max), têm sido cultivadas nestas áreas. Com diferentes qualidades de resíduos culturais, espera-se uma alteração na dinâmica da matéria orgânica do solo (MOS) e, consequentemente, do nitrogênio (N). O objetivo deste estudo foi avaliar a influência de resíduos culturais de arroz, soja e sorgo na quantidade de N em frações físicas da MOS de dois solos de terras baixas, utilizando a técnica de marcação isotópica de 15N das culturas e uma incubação por um ciclo de 180 dias em condição aeróbica e mais 180 dias em condição anaeróbica. Aos 30, 180 e 360 dias de incubação foi quantificado o N remanescente dos resíduos vegetais e destino do N proveniente dos resíduos nos dois solos em frações físicas da MOS >250 μm, 250-53 μm e <53 μm. O solo com maior quantidade de argila+silte recebeu maior quantidade de 15N dos resíduos, enquanto que o alagamento do solo após 180 dias de incubação ocasionou uma perda do N adicionado ao solo pelos resíduos de soja e sorgo. De maneira geral, foram encontradas maiores quantidades de 15N na fração <53 μm, associado aos argilominerais. As perdas de N devem ser consideradas na adubação nitrogenada para as culturas sequentes nos sistemas de rotação de culturas com arroz irrigado.

ABSTRACT: The state of Rio Grande do Sul has about 20% of the total area as lowland soils, suitable for flooded rice (Oryza sativa). In order to mitigate damage caused by rice monoculture, new crops such as sorghum (Sorghum bicolor) and soybean (Glycine max) have been cultivated in these areas. With different qualities of crop residues, it is expected a change in soil organic matter (SOM) dynamics and consequently, nitrogen (N) availability. The objective of this study was to evaluate the influence of rice, soybean and sorghum crop residues on the N present in physical fractions of SOM of two lowland soils, using labeled 15N technique, under incubation for 180 days in aerobic condition and more 180 days in anaerobic condition. At 30, 180 and 360 days of incubation the remaining N of the plant residues and N destination from the residues in both soils were quantified in the physical fractions of SOM >250 μm, 250-53 μm and <53 μm. The soil with higher amount of clay+silt received a larger quantity of 15N from residues, while flooding of the soil after 180 days caused a loss of N added to the soil by the soybean and sorghum residues. In general, larger amounts of 15N were reported in the fraction <53 μm, associated with clay minerals, throughout the incubation period. These N losses should be considered in N fertilization for the following crops in rotation with flooded rice.

A tomada de potência (TDP) de um trator agrícola tem por principal finalidade transmitir a potência gerada no motor, para acionamento de órgãos ativos das máquinas agrícolas. Tendo em vista a necessidade de se aumentar a eficiência energética na agricultura, alguns fabricantes disponibilizam para os agricultores uma configuração de TDP que proporciona o acionamento dessas máquinas a um regime de rotação menor do motor do trator. Assim, a rotação da TDP é mantida podendo-se obter uma redução do consumo de combustível. Este trabalho objetivou quantificar o consumo de combustível de um trator agrícola, operando com duas configurações de TDP (normal e econômica) em duas áreas agrícolas de relevo distinto. Como resultado, evidencia-se que, com a utilização da TDP econômica, tanto o consumo horário quanto o consumo operacional de combustível, em ambas as áreas trabalhadas, foi menor quando comparado à TDP normal.

The agricultural tractor power take-off main purpose is to transmit the power generated in the engine to drive the active organs of farm machinery. In view of the need to increase the energy efficiency in agriculture, some manufacturers provide for farmers a power take-off with economy mode, which provides to the drive these machines at a reduced engine rpm. Thus, the PTO speed is maintained and can obtain a reduction in fuel consumption. This research aimed to quantify the fuel consumption of a tractor with two power take-off configurations in two agricultural areas with different reliefs. As result, it is evident that the use of economy mode, both hourly fuel consumption and operational fuel consumption in both areas worked less when compared to standard power take-off.

O objetivo deste trabalho foi determinar os efeitos de três doses de fumonisina B1 (0, 100 e 200 mg/kg de ração) sobre variáveis biológicas (peso relativo de fígado [RWL], proteínas plasmáticas totais [TPP], albumina [Alb], cálcio [Ca], fósforo [P], ácido úrico [UA], alanina aminotransferase [ALT], aspartato aminotransferase [AST], gama glutamiltransferase [GGT] fosfatase alcalina [AP], colesterol total [Chol], triglicerídeos [Tri], relação esfinganina:esfingosina [SA:SO] e proteína C-reativa [CRP]), avaliação morfológica do intestino delgado (altura de vilosidades [VH], profundidade de criptas [CD] e relação entre vilosidade e cripta [V:C]), avaliações histológicas e no desempenho (peso corporal [BW], consumo de ração [FI] e conversão alimentar [FCR]) de frangos de corte. Efeitos significativos da FB foram observados sobre BW e FI (diminuição), sobre RWL, TPP, Ca, ALT, AST, GGT, Chol e Tri (aumento) aos 14 e 28 dias. Além disso, houve aumento significativo nos parâmetros FCR, Alb, P, SA:SO e CRP e redução nos parâmetros UA, VH e V:C somente aos 28 dias. Lesões histológicas significativas foram observadas no fígado e rins das aves intoxicadas, tanto aos 14 quanto aos 28 dias. Estes resultados indicam que a FB tem um efeito significativo sobre variáveis biológicas e de desempenho de frangos de corte.

The objective of this study was to determine the effects of three doses of fumonisin B1 (0, 100, and 200mg/kg of feed) on biological variables (relative weight of liver [RWL], total plasma protein [TPP], albumin [Alb], calcium [Ca], phosphorus [P], uric acid [UA], alanine aminotransferase [ALT], aspartate aminotransferase [AST], gamma glutamyltransferase [GGT], alkaline phosphatase [AP], total cholesterol [Chol], triglycerides [Tri], sphinganine-to-sphingosine ratio [SA:SO], and C-reactive protein [CRP]), morphological evaluation of the small intestine (villus height [VH], crypt depth [CD], and villus-to-crypt ratio [V:C]), histological evaluation, and on performance (body weight [BW], feed intake [FI], and feed conversion rate [FCR]) of broiler chickens. Significant effects of FB were observed on BW and FI (reduced), on RWL, TPP, Ca, ALT, AST, GGT, Chol, and Tri (increased) at both 14 and 28 days evaluations. In addition, significant increase was observed on FCR, Alb, P, SA:SO, and CRP and significant reduction in UA, VH, and V:C only at the 28 days evaluation. Significant histological lesions were observed on liver and kidney of FB inoculated broilers at 14 and 28 days. Those results show that FB has a significant effect on biological and histological variables and on performance of broiler chickens.

O objetivo desta pesquisa foi estudar os efeitos das aflatoxinas sobre o desempenho e plumagem de frangos de corte. Foram utilizados 240 pintos machos, alimentados de 1 a 42 dias de idade com ração ad libitum sem aflatoxinas (grupo controle) e contaminada com 3mg de aflatoxinas/kg de ração (grupo tratado). As aves foram analisadas duas vezes ao dia em relação ao seu desenvolvimento. O consumo de ração e peso dos animais foram avaliados ao final de cada fase de criação (21, 35 e 42 dias). Ao final do experimento, realizaram-se as avaliações patológicas, a pesagem das penas e a avaliação dos seus aminoácidos. As aves do grupo tratado apresentaram sinais caracteristicos de intoxicação por aflatoxinas, como desuniformidade da estatura, redução no consumo de ração e ganho de peso e alterações microscópicas e macroscópicas em órgãos e tecidos. Observou-se que o coração e o fígado das aves intoxicadas apresentaram um incremento significativo no peso médio relativo, a massa de penas foi reduzida significativamente (33,8%) e não houve alterações na concentração e na composição dos aminoácidos, apesar do baixo desempenho dos animais intoxicados.

This work had the goal to study the exposure effect of broiler chickens to aflatoxins during a period of 42 days related to its development in size and feathers. Two experimental groups of male chicks were treated with ad libitum food, one group without aflatoxins (control group) and other using contaminated food with 3mg/kg of aflatoxins (treated group). Birds were evaluated twice a day to observe its performance and consumption of food. The weights were measured at the end of each breeding phase (21, 35 and 42 days). At the end of the experiment animal size, weight, amount of feathers, organs and amino acids profile in blood were analyzed and compared between the two groups. The treated group showed classical signs of intoxication with aflatoxins such as less uniformity, less feed consumption and body weight gain. Also some macroscopic and microscopic organs and tissue changes were observed. Evaluation of heart and liver of the treated group showed an increase in their average relative weight. Feather mass in this group was significantly reduced (33.8%), but its amino acids concentration was not affected despite the low performance of the intoxicated animals.