Emissão de CO2 e consolidação do solo a curto prazo após atividades de preparo
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Data
2017-07-17
Autores
Silva, Bruna de Oliveira [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Concomitantemente ao desenvolvimento agrícola brasileiro surge a preocupação com os impactos ambientais causados pelo setor, dentre esses, as emissões de CO2 oriundas de práticas de cultivo e manejo dos solos nos sistemas produtivos. Neste estudo, objetivou-se investigar a variação temporal da emissão de CO2 e atributos físicos do solo sob influência do processo de reorganização das partículas do solo após as atividades de preparo do solo. O estudo foi conduzido em três áreas adjacentes medindo 10 × 3 m cada, nas quais foram conduzidos dois sistemas de preparo do solo: (i) enxada rotativa + grade niveladora convencional, representando um preparo intenso do solo (PI); (ii) grade aradora + niveladora, caracterizando um preparo reduzido (PR), e a terceira área envolvida no estudo foi mantida sem revolvimento do solo caracterizando o sistema semeadura direta (SD). Foram realizadas avaliações diárias da emissão de CO2 do solo (FCO2), temperatura e umidade do solo, distribuição de classes de poros, densidade do solo, resistência do solo à penetração, porosidade livre de água, diâmetro médio ponderado, índice de estabilidade de agregado, carbono orgânico total e carbono orgânico particulado, durante um período de 29 dias após o preparo do solo. No primeiro dia após preparo, a FCO2 foi 87% superior na parcela PI (3,86 µmol m-2 s-1) quando comparado a PR(2,06 µmol m-2 s-1) e 147% superior quando comparado a parcela sem distúrbio (1,56 µmol m-2 s -1). A densidade e a resistência do solo à penetração apresentaram menor variação a partir do 12º dia após as atividades de preparo do solo, tal efeito foi considerado como um processo natural de consolidação do solo, sendo que esse processo influenciou na variação temporal da emissão de CO2 do solo. A distribuição de classes de poros são atributos físicos importantes para explicar as variações temporais da emissão de CO2 do solo, e essas classes são influenciadas pelo manejo adotado. Portanto, o estudo desses atributos deve ser levado em consideração quando avaliada a variação da emissão de CO2 em solos agrícolas.
The development of the Brazilian agricultural sector necessarily implies a greater concern with diverse environmental impacts caused by the sector, among them the CO2 emissions from soil and crop management in the production systems. This study aimed to investigate the CO2 emission associated to physical properties in the short term after soil management submitted to different intensities. The study was conducted in three adjacent areas, measuring 10 × 3 m each, in which two soil tillage systems were performed: (i) rotary hoe + conventional harrow representing a much more intense soil tillage (PI); (ii) disc plowing + disc harrowing, characterizing a reduced soil tillage (PR), and in the third area was no-tillage (SD), without disturbance. They were carried out daily evaluations of soil CO2 emissions (FCO2), temperature and soil moisture, bulk density, soil resistance to penetration, water-free porosity, mean weight diameter, stability indices of soil aggregates, total organic carbon and particulate organic carbon, over a period of 29 days. On the first day after management, FCO2 was 87% higher in PI (3.86 μmol m-2 s-1) when compared to PR (2.06 μmol m-2 s-1) and was 147% higher when compared to area without disturbance (1.56 μmol m-2 s-1).The physical soil attributes: bulk density, resistance to penetration; showed lower variation from day 12 after soil management, this effect was considered in this study as a natural process of soil consolidation, and this process may also have influenced the temporal variation of soil CO2 emission. However, future studies involving a longer period of time are necessary in order to establish more concrete relationships. However, future studies involving a longer period of time are necessary to fortify the interrelations observed in this study. The distribution of pore classes are important physical attributes to explain the temporal variations of the soil CO2 emission, and these classes are influenced by the adopted management. Therefore, the study of these attributes should be taken into account when evaluating the variation of CO2 emission in agricultural soils.
The development of the Brazilian agricultural sector necessarily implies a greater concern with diverse environmental impacts caused by the sector, among them the CO2 emissions from soil and crop management in the production systems. This study aimed to investigate the CO2 emission associated to physical properties in the short term after soil management submitted to different intensities. The study was conducted in three adjacent areas, measuring 10 × 3 m each, in which two soil tillage systems were performed: (i) rotary hoe + conventional harrow representing a much more intense soil tillage (PI); (ii) disc plowing + disc harrowing, characterizing a reduced soil tillage (PR), and in the third area was no-tillage (SD), without disturbance. They were carried out daily evaluations of soil CO2 emissions (FCO2), temperature and soil moisture, bulk density, soil resistance to penetration, water-free porosity, mean weight diameter, stability indices of soil aggregates, total organic carbon and particulate organic carbon, over a period of 29 days. On the first day after management, FCO2 was 87% higher in PI (3.86 μmol m-2 s-1) when compared to PR (2.06 μmol m-2 s-1) and was 147% higher when compared to area without disturbance (1.56 μmol m-2 s-1).The physical soil attributes: bulk density, resistance to penetration; showed lower variation from day 12 after soil management, this effect was considered in this study as a natural process of soil consolidation, and this process may also have influenced the temporal variation of soil CO2 emission. However, future studies involving a longer period of time are necessary in order to establish more concrete relationships. However, future studies involving a longer period of time are necessary to fortify the interrelations observed in this study. The distribution of pore classes are important physical attributes to explain the temporal variations of the soil CO2 emission, and these classes are influenced by the adopted management. Therefore, the study of these attributes should be taken into account when evaluating the variation of CO2 emission in agricultural soils.
Descrição
Palavras-chave
Porosidade do solo, Semeadura direta, Respiração do solo, Revolvimento do solo, Soil porosity, No-tillage, Breathing soil, Soil disturbance