Estoque e Mecanismo de Proteção Física do Carbono no Solo em Manejos Agrícolas

O compartimento terrestre é o maior reservatório de carbono no solo e armazena cerca de três vezes mais que o compartimento atmosférico. Porém, a atmosfera tem aumentado suas concentrações, devido as elevadas emissões de gases de efeito estufa, decorrente principalmente do consumo de combustíveis fosseis e queimadas das florestas. O Brasil é um dos maiores emissores, especialmente de dióxido de carbono, pelo qual o setor de mudanças do uso da terra e florestas são responsáveis majoritariamente pelas emissões. O solo em condições naturais tem um equilíbrio entre a entrada e saída de carbono, no entanto quando o solo é cultivado, principalmente com sistemas convencionais, há uma perda significativa dos estoques de carbono do solo. No entanto, quando é adotado manejos conservacionistas ocorre o mecanismo de proteção física do carbono através da formação e estabilização dos agregados, que dificulta o acesso dos microrganismos a decomposição e mantém estocado no solo, o que mitiga a emissão para atmosfera. Diante do exposto, este trabalho teve como objetivo mostrar como os manejos influenciam no estoque de carbono no solo, e como é atuação do mecanismo de proteção física de agregados em sistemas conservacionistas, demostrando como foram os avanços na pesquisa da interação da matéria orgânica com a formação e estabilização de agregados. Stock and Mechanism of Physical Protection of Soil Carbon in Agricultural Managements A B S T R A C TThe terrestrial compartment is the largest carbon reservoir in the soil and stores about three times as much as the atmospheric compartment. However, the atmosphere has increased its concentrations, due to the high emissions of greenhouse gases, mainly due to the consumption of fossil fuels and forest fires. Brazil is one of the largest emitters, especially of carbon dioxide, for which the sector of land use change and forests are responsible for the majority of emissions. Soil under natural conditions has a balance between carbon input and output, however when the soil is cultivated, mainly with conventional systems, there is a significant loss of soil carbon stocks. However, when conservation management is adopted, there is a mechanism for the physical protection of carbon through the formation and stabilization of aggregates, which hinders the access of microorganisms to decomposition and keeps them stored in the soil, which mitigates the emission into the atmosphere. In view of the above, this study aimed to show how the management influences the carbon stock in the soil, and how the mechanism of physical protection of aggregates in conservationist systems works, demonstrating how advances were made in researching the interaction of organic matter with formation and stabilization of aggregates.Key words: aggregates, carbon dioxide, greenhouse effect, crop-livestock-forest integration, organic matter

Vegetation and Soil Carbon under Various Forest Management Types: Case of Karang Sidemen Community Forest in Lombok, Eastern Indonesia

The condition of community-managed forest areas varies according to biophysics characteristics and management activities. This study aims to investigate the condition of vegetation and soil carbon stocks of various types of forest management by the community in Karang Sidemen Village, Lombok, Indonesia. In the study area, it was found 4 types of landuse management, namely; dense forest-like vegetation (Tp1), moderate vegetation with intensive (Tp2) and less intensive (Tp3) under-stand cultivation, and sparse vegetation resembling dryland agriculture (Tp4). Vegetation condition was analyzed based on satellite derived NDVI index and field observation. Sentinel satellite images for 2015 and 2019, with a resolution of 10x10 m was used. Field data collection was carried out in August 2019. It was made 5 sample plots of 20x20 m for each management type. Vegetation data with diameter (D) ≥ 20 cm, 10 cm ≤D< 20 cm, 2 cm ≤D< 10 cm and D< 2 cm were collected from plots of 20x20 m, subplots 10x10 m, 5x5 m and 2x2 m, respectively. Soil samples were taken diagonally on a 20x20 m plot, at a depth of 0-5 cm, 5-10 cm, 10-20 cm and 20-30 cm. The results showed that the NDVI derived vegetation index for 2015 and 2019 images showed different patterns for the four types of management. The number of species for Tp1, Tp2, Tp3 and Tp4 were 9, 15, 9 and 8 species, respectively. The dominant species are generally from groups of plants providing economic benefits such as avocado (Persea americana), candlenut (Aleurites moluccana), cocoa (Theobroma cacao), coffee (Coffea canephora), jackfruit (Artocarpus heterophyllus), mangosteen (Garcinia mangostana) and guava (Psidium guajava). Soil carbon stocks of the four types of management at a depth of 0-5 cm, 5-10 cm, 10-20 cm and 20-30 cm were18.61-21.04 tons C/ha, 16.56-20.80 tons C/ha, 29.66-34.48 tons C/ha and 27.54 - 33.66 tons C/ha, respectively. The soil carbon stock of denser vegetation is higher than that of medium and sparse vegetation. Therefore, forest management with the community needs to maintain forest-like vegetation.