Abstract Soil organic matter has great importance in chemical, physical and biological processes in soil-plant system. This study aimed to evaluate changes in carbon humic fractions of soil organic matter under different vegetation coverings in Cerrado in Tocantins, Brazil. The work was developed in Eucalyptus sp., Pasture, Agriculture and Cerrado sensu stricto areas. Soil samples were collected in dry period, October, 2018, in trenches 70 x 70 cm at depths 0-10, 10-20, 20-30, 30-40 and 40-50 cm, with six replications. The vegetation cover in Eucalyptus sp. area showed higher levels of total carbon in soil humic fraction. Respectively fulvic acid, humic acid and humin in Eucalyptus sp. area had stocks of 22.09; 2.71 and 20.01% higher than native forest, 32.04; 2.57 and 35.59% higher than pasture and 10.59; 19.19 and 7.61% higher than the agriculture area. Among the different areas evaluated, the soil of Eucalyptus sp. has great potential to increase carbon storage in soil humic fractions.

ABSTRACT The objective of this work was to evaluate the penetration resistance (PR) of a red-yellow latosol submitted to two subsoiling depths for implanting a forest plantation. The subsoiling was evaluated at 40 cm (S-40) and 50 cm (S-50) of depth by determining the soil moisture and soil density, while soil PR was evaluated before and after subsoiling at five points transversely to the subsoiling line (furrow) up to a depth of 60 cm using an electronic penetrometer. The soil density in both treatments was not altered by soil management. Before soil preparation, the soil presented PR values above the critical limit in the 0 cm to 30 cm layers, and after subsoiling a reduction in those values was verified at depth. It can be concluded that the 50 cm (S-50) subsoiling depth is the most suitable for soil preparation in a forest stand implantation.

RESUMO Objetivou-se, com este trabalho, realizar uma avaliação da profundidade de trabalho na qualidade da operação de subsolagem para implantação de povoamentos florestais. O experimento foi realizado em uma empresa florestal localizada no Município de Telêmaco Borba, Estado do Paraná, Brasil, em um Latossolo de textura média. O equipamento utilizado foi um trator de esteiras com potência de 170 HP e peso operacional de 19.000 kg, equipado com lâmina tipo V-shear, tracionando um subsolador de arrasto mono-haste com peso de 5.390 kg, com a operação de subsolagem nas profundidades de 40 e 50 cm. A qualidade da subsolagem foi determinada com base nos aspectos de profundidade, formato e distância entre as linhas de sulcos, com uso de gráficos de controle. Os resultados indicaram a falta de controle no processo relacionado com a profundidade e formato das linhas de preparo do solo na operação de subsolagem em ambos os tratamentos. O preparo do solo realizado a 50 cm de profundidade apresentou os melhores padrões de qualidade nas condições estudadas.

ABSTRACT The objective of this research was to evaluate the effect of work depth in the quality the subsoiling operation for forest planting. The study was conducted in a forest company located in Telemaco Borba, Parana State, Brazil, in an Oxisol of medium texture. The equipment used was a track tractor with power of 170 HP and operational weight of 19,000 kg, equipped with V-shear blade, pulling a drag subsoiler mono haste with weigh of 5,390 kg, working at subsoiling operation in the depths of 40 and 50 cm. The quality of the subsoiling was determined based on the aspects of depth, format and distance between the lines to be planted, with the use of control graphics. The results showed the lack of control in process related to the depth and format of the lines of soil preparation in subsoiling operation in both the treatments. The soil preparation carried out at 50 cm depth showed the best quality standards at the studied conditions.

RESUMO Este trabalho objetivou avaliar os fatores humanos e as condições de trabalho em atividades de implantação e manutenção florestal visando subdiar a melhoria das condições de conforto, segurança e saúde dos trabalhadores. O estudo foi realizado em uma empresa florestal da Região dos Campos Gerais, estado do Paraná. A caracterização dos fatores humanos e das condições de trabalho foi realizada por meio de questionários aplicados na forma de entrevistas com 72 trabalhadores que atuavam em atividades silviculturais. De acordo com os resultados, a idade média dos trabalhadores foi de 34,9 anos, sendo a maioria de origem rural, casados, com baixo nível de escolaridade e com pouco tempo de experiência na empresa e na função, representados por 14,9 e 12,5 meses, respectivamente. Na opinião da maioria dos trabalhadores, os óculos de proteção utilizados na aplicação de herbicidas foram apontados como maiores causadores de desconforto no trabalho.

ABSTRACT The objective of the present study was to evaluate the human factors and working conditions in forestry maintenance and planting operations in order to improve comfort, safety and health conditions of workers. The study was conducted in a forest company located in the region of Campos Gerais, Parana State. The characterization of human factors and work conditions was conducted by interviews with 72 workers of syilviculture activities. The results indicated that the workers’ average age was 34.9 years, most of them from rural origin, married, with low level of education, and short time experience in the company and the function, 14.9 and 12.5 months, respectively. In the opinion of most of the workers, the protection glasses used in the herbicide application activity were identified as a cause of discomfort at work.

ABSTRACT The purpose of this research was to evaluate the factors that intervene and alter the biomechanical models adequate posture during the stage of implantation and forest maintenance, in order to suggest the adoption of the correct posture during the execution of forest operations. The research was carried out in farms in the south of the State of the Espirito Santo, Brazil, where there is a predominance of declivous relief. The postures were analyzed in each stage of the implantation (semi-mechanized mowing, manual and semi-mechanized tillage, fertilization and planting) and of the forest maintenance (crown, fertilization, manual and semi-mechanized pruning). The data were obtained using video filming and were analyzed using the OWAS method of analysis of positions in the work, generating standard postures. Based on the results, it was concluded that the postures adopted in the operations of crown, manual and mechanized tillage, mechanical mowing, and manual pruning were considered critical and need corrections in a near future.

RESUMO Esta pesquisa teve o objetivo de avaliar os fatores que interferem e alteram os modelos biomecânicos posturais adequados durante as etapas de implantação e manutenção florestal, a fim de sugerir a adoção de posturas corretas durante a execução das operações florestais. A pesquisa foi realizada em propriedades rurais no sul do Estado do Espírito Santo, onde há o predomínio de relevo declivoso. As posturas foram analisadas em cada etapa da implantação (roçada semimecanizada, coveamento manual, coveamento semimecanizado, adubação e plantio) e da manutenção florestal (coroamento, adubação, desrama manual e desrama semimecanizada). Os dados foram obtidos utilizando-se vídeo filmagem e analisados por meio do método OWAS de análise de posturas no trabalho, gerando posturas padrões. Baseando-se nos resultados, concluiu-se que as posturas adotadas nas operações de coroamento, coveamento manual, coveamento mecanizado, roçada mecânica e desrama manual foram consideradas críticas, necessitando de correções em futuro próximo.